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Simon M. Shane FRCVS, PhD, MBL, ACPV Adjunct Professor North Carolina State University
Professor Emeritus School of Veterinary Medicine Louisiana State University USA
Published by: American Soybean Association 541 Orchard Road #11-03 Liat Towers Singapore 238881 Tel: (65) 6737 6233 Fax: (65) 6737 5849 Website: www.asasea.com
Handbook on Poultry Diseases 2nd Edition
Copyright©2005 by American Soybean Association All Rights Reserved. No part of this publication may be produced or distributed in any form or by any means, or stored in a data base or retrieval system, without prior written permission of the copyright owners. Printed in Singapore, 2005 PO 52-2005 MITA (P) 052/04/2005 MO4GX19403-062005-1000
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.................................0 PREVENTION OF DISEASE ..........................1 Conceptual Biosecurity ............0 2.0 General Principles ............... 15 4.............................................................3 ............0 INTRODUCTION ............................3 3.................. 8 HEALTH AND PERFORMANCE OF POULTRY IN TROPICAL CLIMATES ........... 13 Management of Flocks at High Temperature ..........1..............2........... 26 i 4............................ 6 2.....................1.........................................5 Dissemination by Wind ........................... 13 Design of Housing in Tropical Countries ..............7 Feed .........................3...3 Physiological Effects of High Ambient Temperature ....2 4.....2 2.................2 Transmission on the Egg Shell ............... 22 4...................... NUTRITION AND BIOSECURITY ........1........2...............2 Structural Biosecurity ..................... 2 1.................................................... 21 4......1.....8 Vaccines .................................................................TABLE OF CONTENTS PREFACE 1 MANAGEMENT................. 23 4......................................................1 Mechanisms of Disease Transmission .....................1 Transovarial Route ........................ 21 4...............1 Definitions .1.................... 21 4. 24 Decontamination of Housing and Equipment . 23 4....2 3................................................................................................4 Indirect Transmission ....... 26 4............................................................... 22 4.........3...... 3 ECONOMIC CONSIDERATIONS IN THE PREVENTION AND CONTROL OF POULTRY DISEASES .. 21 4.............. 13 3.................. 26 4...... 22 4..........................1 3...................1 2........1...................3 Operational Biosecurity ................................2 Decontamination ................. 22 4........... 21 4..................2.......................6 Biological Vectors ............................3 Direct Transmission ..........1.......... 7 Gross Marginal Analysis ................................................... 23 4......................................... 6 Fixed and Variable Costs in Poultry Production . 22 Biosecurity ..............1............................
...............................2...2 5............................ 46 6..4 Fats ............. 48 Control of Disease in Commercial Egg Production Units ...... 47 Control of Disease on Commercial Broiler Farms ..1 Control of Disease in Multiplier Breeder Farms .................................. 57 7................2............................3................................................................................2.........3 Deficiencies of Proteins or Amino Acids ...................................6 4.......... 38 Medication ................ 35 Administration of Vaccines ...................... 47 6................................. 27 Control of Rodents .............2 Operational Biosecurity ............... 51 Control of Disease in Hatcheries ...................... 57 7.................... 35 5.. 30 VACCINATION AND MEDICATION ......................................1....... 57 7...........5 Oxidative Rancidity ..... 46 6..............................1 5............ 27 Disinfection of Poultry Houses ............................1 Structural Biosecurity ..............2 Operational Biosecurity .................................1 Structural Biosecurity ...........................................................4 General Principles ......... 53 6...................0 Disinfectants ...........................4. 56 7................................4 4.............. 47 6..........4 4...................... 29 Quality of Water .. 51 6.................3 4......0 NUTRITION OF CHICKENS AND DIETARY DEFICIENCIES .............2.........................................................2.....................7 5.................. 53 6..0 SPECIAL PROCEDURES RELATING TO CONTROL OF DISEASES IN POULTRY OPERATIONS .2 6.... 35 Significance of Maternal Antibody in Relation to Flock Protection ................................2.................................1....4.............................................1 Structural Biosecurity ............3 6......3 5..............................................4............... 56 7.... 53 6.........................4 7.........1 Operational Biosecurity .............................2 Establishing Nutritional Specifications .......... 28 Control of Free-Living Birds ...................... 56 Nutrient Deficiencies ...............................3......................3.2.................. 38 6..........1 Causes of Nutrient Deficiencies .........5 4.................................. 46 6.... 56 7.1 7.............2 Low Energy Intake .....2 Operational Biosecurity ....... 58 ii .... 26 Public Health Considerations ......................................................
......................................................................... 79 Transmission ........................................................................7 Etiology ...............................................2 9.........................2 11.....4 8............................ 70 INFECTIOUS BURSAL DISEASE ....3 9..................................................................................4 10........................................................................ 69 Occurrence and Economic Significance ...................................................................................................................................................5 8.... 73 Diagnosis .... 72 Transmission ..........................1 10....... 62 IMMUNOSUPPRESSIVE DISEASES .................... 78 11.....7.............0 MAREK'S DISEASE .......................................5 9.....0 NEWCASTLE DISEASE ..................................... 79 11........... 76 Transmission ............................................................................. 72 9................................................. 76 RESPIRATORY DISEASES . 73 10.................3 8................................. 69 Clinical Signs .........................6 10.......................5 10................ 69 8..........................................1 11....................................6 9.... 58 7.................. 73 Prevention ..............................................................................................7 9........ 72 Occurrence and Economic Significance .....................................2................2 8..................... 68 8................................ 79 Occurrence and Economic Significance .........................................3 Quality Control in Feed Manufacture ...................................................................0 CHICKEN ANEMIA . 76 Clinical Signs ....4 9.................. 76 Diagnosis .............................................2 10.6 8............................................. 76 Occurrence and Economic Significance ....................................... 72 Clinical Signs ......... 76 10........................................... 76 Prevention ............. 69 Prevention ...........................................7 Etiology .................................................................................................. 69 Diagnosis and Confirmation ....................1 9..........................................3 10.................................. 69 Transmission ..............6 Vitamin Deficiencies . 69 Pathology ........................................................................................................................................3 Etiology ....................................... 76 Pathology ..............................................0 Etiology ............. 72 Pathology .....1 8................. 79 iii .............................................................................
......................................................4 14................................................................................................ 84 Prevention .0 MYCOPLASMOSIS .................. 80 Diagnosis ..... 87 Clinical Signs .......................................................................... 93 Prevention .....7 Etiology ..........................................................5 12..................7 Etiology ....... 95 15.................................. 84 Diagnosis ..................................................6 12.................. 93 Occurrence and Economic Significance .............................. 87 13.................. 80 Prevention .......... 93 Diagnosis ............................ 93 14.......5 11............4 12................. 93 15.....................................................................................................................................2 13.................5 13........................................ 1 15........................0 INFECTIOUS LARYNGOTRACHEITIS ....................... 95 Transmission ..........................6 13.... 89 14................2 15............................................... 87 Pathology . 88 Diagnosis ..................................................8 Etiology ...................................................................................................................1 12...........................................5 Etiology ..................2 12........ 93 Pathology ..................................... 93 Transmission ............... 93 Clinical Signs ............ 87 Transmission .............................................. 84 Occurrence and Economic Significance .... 88 Recent Outbreaks of H5N1 Avian Influenza ................................................3 14.................. 81 12.............................6 11........ 84 12...........................5 14.......................1 14............... 88 Control in Areas Where Exotic HPAI is Diagnosed .................4 15.... 80 Pathology ..................................3 12.........................2 14.4 13.................................... 85 13.............3 13........................................................................................................................................................................................................................................................................ 95 Pathology ........ 87 Occurrence and Economic Significance .......11........................3 15..........6 14..................................... 95 Occurrence and Economic Significance ..........................0 INFECTIOUS BRONCHITIS ........7 Clinical signs............................ 84 Pathology ........7 13..............................0 AVIAN INFLUENZA .................................................................................................................................. 95 Clinical Signs .................... 84 Transmission ..............................4 11.............................................................................................. 96 iv .............................................1 13........... 84 Clinical Signs .......................................................................................................
.......................... 105 Occurrence and Economic Significance .....................................................................................................................7 18.............5 17............................................................................................................................... 99 16....................... 105 Transmission ..........3 17..........................................................................................................6 15.....1 16....6 18............4 18......................... 108 19.............. 101 17...................................................................................................... 99 Transmission .................................3 18.......................................................15..................8 Etiology ............2 17.................... 101 Clinical Signs ... 99 Prevention .... 106 Prevention .......................0 SWOLLEN HEAD SYNDROME ........................................ 106 Treatment ............................................................................................................ 101 Pathology ...........................2 19................................................................ 106 19.... 105 Pathology ................. 99 Diagnosis ....................................... 108 Occurrence and Economic Significance .................... 104 18............................................................ 105 Clinical Signs ... 100 17...... 101 Occurrence and Economic Significance ....................... 96 16.....................................................................................7 Etiology ..........................................2 18.............. 108 Transmission ...............................................0 SEPTICEMIA AND AIRSACCULITIS ............................. 106 Diagnosis ..8 Diagnosis ...................................................5 16.......... 96 Prevention . 101 Prevention ....................................6 17................................................................................ 96 Treatment .........................4 17.... 101 Transmission .........................8 Etiology ......................................... 99 Pathology .............7 16............0 ASPERGILLOSIS ........................1 19......................................... 99 Treatment ..............................3 Etiology .....................1 17........................................................................... 101 MULTIFACTORIAL CONDITIONS ............7 15.... 99 Clinical Signs ..........................1 18..................................... 108 v ................................................... 105 18.............................................................................4 16.................................................................................................................................................3 16..........................................................5 18.......... 99 Occurrence ........................... 101 Diagnosis ...................2 16......................................................................................................................6 16..................................................0 CORYZA ...
..6 21..................................................6 20............................................ 114 21.1 22................................................................................. 116 Economic Significance ................................... 117 vi ...........................................................2 22................... 108 Pathology .................. 112 Transmission ......................................................7 20... 116 Diagnosis .....................................................................................8 22........................................................................................................................................................................................................................................................7 19......................................8 Etiology .............. 109 Treatment .....................................2 20................................2 21..................5 20.......................... 114 Pathology .............................................................................. 112 20....3 22..............................................9 Etiology .........................5 21...............................................8 Etiology .............................................................................. 117 Prevention ...........0 SALMONELLOSIS-FOWL TYPHOID ..............................3 21...8 Clinical Signs .......................................................................... 112 Treatment ............................................ 109 SYSTEMIC DISEASES ....... 117 Treatment ...19..... 114 Transmission ................................................7 21........7 22..... 114 Treatment .....6 22. 109 Prevention ........................ 111 20................................................................................... 114 Occurrence and Economic Significance ......................4 22............................................................... 112 Pathology ............4 21...........5 19........... 116 Clinical Signs .................... 114 Clinical Signs ....................................................................................................................... 115 22.........................0 SALMONELLOSIS-PULLORUM DISEASE .....................................................6 19.............................3 20...............1 20...................... 114 Prevention ................................................ 112 Diagnosis ........ 116 Pathology ........... 116 22.......................................................................... 113 Prevention .........................................................................4 19. 112 Clinical Appearance ...............1 21................................................................................................. 112 Occurrence and Economic Significance ...........................................................................4 20.. 116 Transmission ................................. 116 Occurrence .....................................5 22.................... 114 Diagnosis . 108 Diagnosis ....................... 113 21.........................0 SALMONELLOSIS-PARATYPHOID........................................
.. 127 26..................... 123 Prevention .........7 Etiology ........................... 120 Diagnosis .................... 123 Pathology .....0 ADENOVIRAL INFECTIONS ...................................................................1 26.................................................................8 Etiology .... 124 Clinical Signs ....................................................6 24................... 121 Treatment ...................................................5 25.3 23..........23................................................................................2 Pathology ... 120 Transmission ....................................... 120 Clinical Signs ...................................................... 123 Clinical Signs ....................................................................................4 23........8 Etiology ................................................................................ 124 Pathology .....4........... 123 Occurrence and Economic Significance ............................................ 123 25............................1 Clinical Signs ......................................... 124 26.............. 123 Treatment ..... 124 25...................................... 121 Prevention ............................................................................................................2 25.................................................3 Diagnosis ..........................................................4 Etiology ......................................... 126 Adenoviral Respiratory Infection ...........................................................................0 PASTEURELLOSIS .............................3 26... 123 Diagnosis .......................................................7 23... 120 23........... 126 Transmission .....................6 25...........1 23.............................. 128 vii 26. 124 Occurrence and Economic Significance ..................4...........2 23................... 127 Inclusion Body Hepatitis .. 126 Occurrence and Economic Significance ..........6 23.............. 121 24..................... 126 26............................................................................................................................5 23....0 SPIROCHETOSIS ..........4......................4 Prevention .1 24........................4 24...........................................4 25.................7 24........................................................................................ 124 24............5 24............................3 24............... 123 Transmission ..............................4............2 24......2 26............. 124 Transmission ..................................................................................................... 126 26.............................................................................................................................................................. 120 Pathology ............................ 124 Diagnosis .........................1 25................3 25....................................................0 AVIAN ENCEPHALOMYELITIS ............ 126 26................... 124 Prevention ..................................................................................................... 120 Occurrence and Economic Significance ................................................................ 126 26.......5 .......................
................................ 130 Pathology ......................................................6......................................1 27...........................................1 Clinical Signs ............................ 135 29....................4 Prevention ....................... 130 Occurrence and Economic Significance ........5 28......7 27................................................. 135 Prevention ...............................................5.....1 Clinical Signs ..... 132 ENTERIC DISEASES ...........................................................0 RUNTING SYNDROME ..............2 27............................ 128 26........... 138 Occurrence and Economic Significance .............. 134 Lesions ....... 134 Transmission ......... 135 Treatment ..............7 28. 127 Egg Drop Syndrome ...................5.............................4 Prevention .............. 134 Occurrence and Economic Significance ............................................................................. 138 Transmission ....3 27..6 Etiology ...............5 29............... 131 Treatment .............. 127 26..........6........... 131 Diagnosis . 127 26....................... 134 Diagnosis ................................................. 127 26............................6 28....1 28...................................................................... 139 viii ........................................................................................................ 128 26...........3 Diagnosis ............... 138 Pathology .......6............................6 26....................... 133 28.. 127 26...... 134 Clinical Signs ................... 130 27..........................3 28......................................................................................................................................... 131 Prevention .2 Lesions ......................................3 29.............2 Lesions ........ 138 Diagnosis ......5.............. 138 29...............2 29.............................0 CLOSTRIDIAL ENTEROTOXEMIA ........................................................................................................................................... 134 28......6........................................................... 138 Clinical Signs ....................................................................4 29...............................................8 Etiology ..........................26. 130 Clinical Signs .......................................5....6 27............................................................................................3 Diagnosis . 130 Transmission .................................2 28............................................. 127 26............................5 27.............................8 Etiology .....0 COCCIDIOSIS ........................................................................................................................................................................4 28............................................................................................4 27................................................................................ 128 27.......1 29................................................................................................................................................
29.7 29.8
Treatment ................................................................................ 139 Prevention ............................................................................... 139
30.0 ENDOPARASITES ............................................................................. 141 30.1 30.2 30.3 Capillariasis ............................................................................ 141 Ascaridiasis ............................................................................. 141 Cestodiasis .............................................................................. 141
LOCOMOTORY ABNORMALITIES ..................................................... 144 31.0 SKELETAL DEFORMITIES AND ARTHRITIS ............................... 145 31.1 31.2 Nutritional Etiology ................................................................ 145 Infectious etiology .................................................................. 146 31.2.1 Mycoplasmosis........................................................... 146 31.2.2 Reoviral Arthritis........................................................ 146 31.2.3 Staphylococcal Arthritis ............................................. 147 Pododermatitis ........................................................................ 148 31.3.1 Alleviation of Locomotory Problems Through Nutrition ..................................................................... 149 Developmental Etiology ......................................................... 152 31.4.1 Twisted Legs .............................................................. 152 31.4.2 Rotated Tibia and Crooked Toes ................................ 152
INTEGUMENTARY CONDITIONS........................................................ 153 32.0 AVIAN POX ........................................................................................ 154 32.1 32.2 32.3 32.4 32.5 32.6 32.7 Etiology. .................................................................................. 154 Occurrence and Economic Significance ................................. 155 Transmission ........................................................................... 154 Clinical Signs .......................................................................... 154 Pathology ................................................................................ 154 Diagnosis ................................................................................ 154 Prevention ............................................................................... 154
33.0 ECTOPARASITES .............................................................................. 156 33.1 33.2 33.3 Mites ....................................................................................... 156 Argasid Ticks .......................................................................... 156 Scaly Leg Mites ...................................................................... 156
33.4 33.5
Lice ......................................................................................... 156 Treatment ................................................................................ 156
34.0 DERMATOMYCOSIS ........................................................................ 160 34.1 34.2 34.3 34.4 34.5 34.6 34.7 Etiology ................................................................................... 160 Occurrence and Economic Significance ................................. 160 Transmission ........................................................................... 160 Clinical Signs .......................................................................... 160 Diagnosis ................................................................................ 160 Treatment ................................................................................ 160 Prevention ............................................................................... 160
MISCELLANEOUS CONDITIONS ........................................................ 162 35.0 MYCOTOXICOSES ........................................................................... 163 36.0 LEUCOCYTOZOONOSIS ................................................................. 168 36.1 36.2 36.3 36.4 36.5 36.6 36.7 37.8 Etiology ................................................................................... 168 Occurrence and Economic Significance ................................. 168 Transmission ........................................................................... 168 Clinical Signs .......................................................................... 168 Pathology ................................................................................ 168 Diagnosis ................................................................................ 168 Treatment ................................................................................ 168 Prevention ............................................................................... 168
DISEASES OF WATERFOWL ................................................................. 170 37.0 DUCK VIRAL ENTERITIS ................................................................ 171 37.1 37.2 37.3 37.4 37.5 37.6 37.7 37.8 Etiology ................................................................................... 171 Occurrence and Economic Significance ................................. 171 Transmission ........................................................................... 171 Clinical Signs .......................................................................... 171 Pathology ................................................................................ 171 Diagnosis ................................................................................ 172 Treatment ................................................................................ 172 Prevention ............................................................................... 172
38.0 DUCK VIRAL HEPATITIS ................................................................ 173 38.1 38.2 38.3 38.4 38.5 38.6 38.7 38.8 Etiology ................................................................................... 173 Occurrence and Economic Significance ................................. 173 Transmission ........................................................................... 173 Clinical Signs .......................................................................... 173 Pathology ................................................................................ 173 Diagnosis ................................................................................ 173 Treatment ................................................................................ 174 Prevention ............................................................................... 174
39.0 DUCKLING SEPTICEMIA ................................................................ 175 39.1 39.2 39.3 39.4 39.5 39.6 39.7 39.8 Etiology ................................................................................... 175 Occurrence and Economic Significance ................................. 175 Transmission ........................................................................... 175 Clinical Signs .......................................................................... 175 Pathology ................................................................................ 175 Diagnosis ................................................................................ 175 Treatment ................................................................................ 175 Prevention ............................................................................... 175
40.0 CHLAMYDIOSIS ............................................................................... 176 40.1 40.2 40.3 40.4 40.5 40.6 40.7 40.8 Etiology ................................................................................... 176 Occurrence and Economic Significance ................................. 176 Transmission ........................................................................... 176 Clinical Signs .......................................................................... 176 Pathology ................................................................................ 176 Diagnosis ................................................................................ 176 Treatment ................................................................................ 176 Prevention ............................................................................... 177
41.0 ANNEXURES ..................................................................................... 178 41.1 41.2 41.3 41.4 Conversion of U.S. Metric Weights and Measures ................. 179 Schedule of Therapeutic Drugs ............................................... 181 Differential Diagnoses of Avian Diseases ............................... 183 Abbreviations .......................................................................... 187
.... 181 41....1 CONVERSION OF U..... 183 41.....................LIST OF ANNEXES 41........... 187 xiii ..........................4 ABBREVIATIONS ......S.3 DIFFERENTIAL DIAGNOSES OF AVIAN DISEASES .... METRIC WEIGHTS AND MEASURES ....................... 179 41...........................2 SCHEDULE OF THERAPEUTIC DRUGS ...........
production is impacted by combinations of infections and parasites which are invariably complicated by intercurrent nutritional. It is emphasized that in the context of Asia.PREFACE The second edition of the ASA Handbook on Poultry Diseases has been prepared for the American Soybean Association to assist veterinarians. 2005 1 . Simon M. Specialists and consultants affiliated to the American Soybean Association are willing to assist producers. and avian health professionals to diagnose. environmental and managemental deficiencies. poultry organizations. and universities with additional information on specific aspects of the control and prevention of poultry disease. including suggestions to be included in subsequent printings. cooperatives. Most frequently. treat and prevent diseases in poultry flocks. Shane < sshane@nc. The American Soybean Association encourages constructive comments on this 2nd edition of the Poultry Disease Handbook. students.rr. some diseases such as avian influenza occur as epornitics.com > April. Careful evaluation of the history and application of modern techniques are necessary to diagnose and resolve complex infectious multi-factorial diseases.
Prevention of disease depends on a comprehensive program incorporating a sequence of planning. and salmonellosis continue to erode profit margins. In addition.1.1). salmonellosis and reoviral infection. reoviral stunting syndrome and swollen head syndrome are examples of emerging diseases affecting flocks in Asia. Strategies to prevent infection are based on the purchase of breeding stock free of vertically-transmitted disease. village cooperatives and in integrated operations. Africa. During the past two decades. implementing and control in a repetitive cycle (Figure 1. Productivity and profitability are enhanced by application of sound principles of biosecurity. primary breeders of broiler. and Latin America. chronic. vaccination. low-intensity infections such as coryza. Improving efficiency increases the availability of eggs and poultry meat to supply the protein needs of populations in countries with expanding demand. These should incorporate projections of risk of infection and compare the production parameters and costs for diseased and healthy flocks. pasteurellosis. egg and laying strains have eliminated vertically-transmitted diseases from their elite and great-grandparent generations. The relative importance and contribution of these strategies can be calculated using simulation studies. infection of grandparent and parent flocks occurs in many developing countries resulting in dissemination of diseases including mycoplasmosis. and management.0 INTRODUCTION The purpose of the ASA Handbook on Poultry Diseases is to acquaint veterinarians and poultry health professionals with current information on the diagnosis and prevention of poultry disease in commercial broiler and egg production flocks in emerging and established industries.2): 3 . reduces the potential losses caused by both catastrophic and erosive infections on commercial-scale farms. highly pathogenic influenza. Vaccination of parent flocks and progeny and appropriate levels of biosecurity represent the components of disease prevention subject to direct managemental control. Angara disease. Improved biosecurity and an awareness of the need for appropriate vaccination programs. virulent infectious bursal disease. The components of biosecurity comprise a hierarchy with each of 3 levels influencing the cost and effectiveness of the entire program (Figure 1. Unfortunately.
bulk feed installations. Structural biosecurity can be enhanced in the intermediate term with appropriate capital investment. change rooms. • • 4 . Generally. Siting of farms in relation to public roads and service facilities such as hatcheries.• Conceptual Biosecurity: The primary level represents the basis of all programs to prevent disease. and avoid contact with free-living birds. Decisions concerning conceptual biosecurity influence all subsequent activities relating to prevention and control of disease. and the interior finishes in houses. Remedial action may often be too late to respond to the emergence of a new disease or an epornitic of a catastrophic infection such as highly pathogenic avian influenza. allweather roads. exclusion of rodents and wild birds. erection of fences. These activities can be modified at short notice to respond to disease emergencies. reduce biodensity. construction of drainage. feed mills. and processing plants has a profound impact on the effectiveness of a program to maintain optimal standards of production. Operational Biosecurity: The third level comprises routine managemental procedures intended to prevent introduction and spread of infection within a complex or enterprise. Structural Biosecurity: The second level of biosecurity includes considerations such as the layout of farms. participation by all levels of management and labor and appropriate monitoring of the health status and immunity of flocks contributes to effective operational biosecurity. Constant review of procedures. defects in conceptual biosecurity cannot be changed in response to the emergence of new diseases which may result in severe losses or even failure of an enterprise. equipment for decontamination. Conceptual biosecurity includes selecting the location of a complex or operation in a specific area to separate different types of poultry.
2 HIERARCHY OF BIOSECURITY OPERATIONAL STRUCTURAL CONCEPTUAL 5 .1 CYCLE OF MANAGEMENT Evaluation of Risk & Consequences of Disease Planning of Biosecurity & Disease Prevention Strategies Analysis & Review of Production & Financial Performance Implementation of Biosecurity & Vaccination FIGURE 1.FIGURE 1.
are the two significant variables required to quantify the decline in production which may follow exposure to a disease. Cost-effective programs of biosecurity and vaccination are required to prevent or limit the impact of disease.0 ECONOMIC CONSIDERATIONS IN THE PREVENTION AND CONTROL OF POULTRY DISEASES General Principles The primary purpose of any enterprise is to maximize return on investment over the long-term. should be calculated for a period corresponding to the operating life of the investment. the investment can be considered justifiable. and feed conversion efficiency must exceed capital and operating expenditures on disease prevention. It is emphasized that the incremental return in the form of enhanced egg production. A decision to invest in improvements which promote biosecurity should be based on an anticipation of return within a defined. The benefit-to-cost ratio can be used to relate expenditure on resources and management efforts to the monetary value of improved performance. Changing rooms. Risk of exposure and consequences of infection. derived from improved performance attributed to the absence of disease. Programs of emergency treatment and long-term prevention are justified for severe diseases which have a profound impact on production. The net present value (NPV) of an investment in biosecurity can be calculated from the annual cash flows. Aggressive counter measures are required under conditions which predispose to a high risk of infection. It is therefore necessary to market poultry. There is considerable difficulty in predicting the potential loss arising from a disease or projecting the probability of an outbreak. The NPV method can be used to select the most beneficial program to prevent disease from among 6 2. If the NPV exceeds the cost of improvements.1 . and preferably short to intermediate time period. growth rate. hatchability. discounted by an appropriate interest factor. meat products. The future cash flows. liveability. where the prevalence of endemic diseases severely affects production efficiency or where the value of eggs and meat is high in relation to expenditure on biosecurity and vaccination. It is necessary to invest capital in adequate poultry housing and ancillary installations to attain a suitable level of biosecurity. fences and equipment to decontaminate hatcheries and housing are examples of assets which reduce the probability of introducing disease.2. and eggs at a price which allows farmers or integrators to maintain profitability in a competitive market.
Total costs are represented by the area which encompasses both fixed and variable costs. At a higher throughput. and lease payments.a range of alternatives. vaccines and medication. fuel. 2. there are limits to increasing production volume.75 to 1. Delaying slaughter of a broiler flock to attain a higher live mass (1. Implementing these management changes will increase the risk of disease and intensify the financial impact of infections. Fixed costs do not change as a result of an increase in the volume of production and include depreciation. Variable costs are proportional to the volume of production. A decrease in broiler weight delivered to a plant attributed to increased mortality or depressed growth rate will adversely affect production cost and efficiency. In this example.2 Fixed and Variable Costs in Poultry Production Costs relating to live bird production can be classified into fixed and variable components. salaries. given prevailing production costs and revenue. labor. interest on fixed capital.95 kg) may increase biomass by 11%. are examples of this category of production costs. unit selling price is considered constant over volume of throughput and accordingly revenue is linear and proportional to the quantity produced. Altering stocking density from 20 to 25 birds/m2 increases throughput by 25%. Reducing intercrop interval from 10 to 5 days may result in an 8% increase in broiler live mass over a year. and feed mills operate at a break-even cost approximating 70% to 80% of design capacity due to their relatively high proportion of fixed costs. hatcheries. The concept of apportioning expenditure is important in projecting the effects of disease on total production cost. packaging material. It is emphasized that the validity of any investment decision is dependent on selecting an appropriate value for the risk of infection and accurately projecting the consequences of disease. Processing plants. purchase of day-old chicks and breeding stock. Fixed costs which are constant are illustrated by the line parallel to the horizontal (quantity) axis. variable cost assumes a greater proportion of total cost. overhead. At this level of production fixed costs represent approximately half of the total cost.1 shows the relationship between total cost. Figure 2. Offsetting fixed costs by increasing production level is the basis of efficiency through economy of scale. The severity of viral respiratory diseases such as bronchitis or 7 . In the context of individual farms. Feed. volume of production and profit. At the break-even point (quantity Qo) total revenue is numerically equal to total costs. which benefits progressive integrations and cooperatives in mature industries.
3 considers the effect of three alternative approaches to preventing a disease which has a 0. vaccination costing $1.460 for increased biosecurity. It is determined that the respective gross margins derived from the flock under conditions of no action are $3. unit revenue. The inputs required to determine the gross margin attributable to a specific program are listed for an ongoing poultry operation over a specific time period.000 provides the highest of $8.laryngotracheitis is influenced by environmental and clinical stress. The technique evaluates alternative methods of preventing disease in the context of prevailing costs and revenue. The format table for gross marginal analysis is shown in Figure 2. The corresponding gross margins generated when flocks are subjected to either biosecurity alone (strategy #1) or vaccination alone (strategy #2) can be calculated and entered into a pay-off table. Secondary infections such as E. Expected monetary values are influenced by changes in variable costs.000 and $5.2. feeding space. coli septicemia will intensify losses in proportion to increased biomass.400.000 with and without exposure to disease. biosecurity (#1) or vaccination (#2). 2. costing $2.3 Gross Marginal Analysis This analytical technique can be applied to relate expenditure on disease prevention with output over a specific time period. In the given example. Ventilation. The values calculated from the gross marginal analysis are entered into a pay-off table which depicts the financial result of a selected option. immuno-suppression or environmental stress. The options available to the producer include: no action ("base = 0").000 and $10. A series of analyses can be performed reflecting alternative prevention strategies and probabilities of disease exposure.800 for no action.6 probability of occurrence. Figure 2. compared to $6. The expected monetary value of each prevention strategy is calculated by multiplying the probability factor with outcome as shown. and the probability of infection. mycoplasmosis or coccidiosis may be exacerbated by increased biodensity. Variability in the impact of a disease occurs due to change in the pathogenicity of the causal organism. the presence of secondary agents. Gross marginal analysis allows producers to project the possible outcome of a program with uncertain risks and consequences of infection. drinking points and floor area represent the limiting health factors for flocks when output is increased. capacity. The effect of intercurrent low-grade conditions such as pasteurellosis. Changes in these factors influence the outcome of exposure of a flock to infection and requires relaxation or intensification of the preventive strategy depending on the 8 .
and injection of embryos and chicks with mycoplasmacidal drugs. The low cost of ND and HPAI vaccination and the relative efficiency in improving liveability and enhancing the growth rate or egg production in infected survivors reduces losses associated with minimal expenditure as designated by the curve LoL1. Figure 2. Under certain conditions. such as intensifying the vaccination program and implementing biosecurity will result in an incremental reduction of losses. Eventually the economic optimum is reached (point A) at which a monetary unit of expenditure on control generates only a single unit of return. Additional prevention and control activities will in fact reduce gross margin and generate a negative benefit:cost ratio. such as the need to eradicate a vertically transmitted infection in breeding stock or to suppress a disease of zoonotic significance. This sequence may be illustrated by the intensive programs to eradicate mycoplasmosis by the primary broiler breeders during the 1960's and 1970's. control measures are extended beyond the economic optimum. These measures together with pre-incubation heattreatment of eggs to destroy Mycoplasma spp and enhanced biosecurity and monitoring of pure-line flocks maintained in strictly-isolated small groups eradicated the disease in elite lines.4 depicting expenditure and return from control of disease shows the relationship between expenditure on prevention and control measures (horizontal axis) and the loss associated with introduction of disease (vertical axis). As expenditure on control of velogenic Newcastle disease (vvND) or highly pathogenic avian influenza (HPAI) by effective vaccination is increased. Ultimately the technical optimum (B) is attained.circumstances. At this point additional efforts to prevent disease will not achieve any measurable reduction in losses. the loss in output is reduced. 9 . Increased outlay on disease prevention and control. Control measures included pressure-differential treatment of eggs with antibiotics.
management. health care) Total value at the beginning of the period plus all costs [ (1) + (2) + (3) ] Value of flock at the end of the period Value of chickens and products sold Revenue from by-products Total value at the end of the period [ (5) + (6) + (7) ] Gross margin [ (8) .FIGURE 2.2 GENERAL FORMAT FOR GROSS MARGIN ANALYSIS (1) (2) (3) (4) (5) (6) (7) (8) (9) Value of inventory at the beginning of the period Cost of chicks/flocks purchased Variable costs (feed.(4)] 10 .1 CONCEPTUAL RELATIONSHIP BETWEEN COST AND REVENUE FIGURE 2.
6 (1 -X) = (1 .400 $2.6) = 0.000 $9.0.FIGURE 2.X)] = $6.800 [f x (1 .000 d e f $10.X)] $3.X)] = $5.3 FORMAT OF PAY-OFF TABLE CONSIDERING ALTERNATIVE PREVENTIVE STRATEGIES Possible outcomes Probability of occurrence With disease Without disease X = 0.600 = (c x X) $4.800 = (b x X) $3.400 (Strategy #l) (Strategy #2) 11 .000 $6.000 Expected monetary value associated with alternative strategies: (Base #0) = (a x X) $1.800 + + + + + + [d x (1 .000 [e x (1 .000 $8.000 $7.800 $4.4 Financial result of alternative strategies in designated monetary unit ($) no action biosecurity vaccination #0 #1 #2 a b c $3.600 = $8.
0 HEALTH AND PERFORMANCE OF POULTRY IN HOT CLIMATES Physiological Effects of High Ambient Temperature Exposure of poultry flocks to ambient temperature above the zone of minimum metabolism results in an increase in endogenous heat production. 3. Prolonged hyperpnea results in excessive excretion of carbon dioxide resulting in respiratory alkalosis.2 Design of Housing in Tropical Countries Convection-ventilated housing is most frequently used in temperate and tropical areas where moderately high seasonal temperatures occur.1 3. growth rate. Structures should be designed to permit passive airflow over the flock. An increase in convective heat transfer as a result of air movement is proportional to air velocity of up to 100 m/minute. Panting facilitates evaporative cooling. Respiratory rate can increase from 22 breaths/minute (bpm) to 200 bpm when ambient temperature is increased from 27ºC to 45ºC within 20 minutes. and above 38ºC. and insulation. Exposure to high ambient temperature has a profound economic impact on liveability. This effect is mediated through T-cell or regulatory amplifier cell response. Convective transfer of heat is the major thermo-regulatory mechanism of chickens and depends on movement of air by natural or fan-powered ventilation. Convection houses should not exceed 10 m in width to facilitate cross flow of air at low velocity. Roof overhang should extend at least 0.3. egg shell quality. chickens are almost entirely dependent on latent heat loss for thermoregulation. The significant design characteristics for convection-ventilated houses relate to internal dimensions. Cellular immunity is also suppressed by prolonged exposure to temperatures in excess of 36ºC. egg production. Houses should be oriented in an east-west direction to limit solar heat load. Size and siting of houses in relation to local topography are critical to achieving satisfactory results. Hyperpnea (panting) occurs in mature chickens exposed to temperatures exceeding 30ºC. The lateral ventilation openings should comprise at least 60% of the side 13 . It is presumed that a reduction in circulating antibody is associated with a corticosteroid-induced change in serum ions. provided ambient air temperature is below body temperature. reducing antibody titer. provision of adequate air inlets.8 m to limit solar gain through the side walls. and the interior height at the apex should not be less than 4 m to reduce air temperature at bird level. and feed conversion efficiency. Exposure to high environmental temperature for extended periods will suppress the humoral immune response of chickens.
All systems function on the principle of adiabatic cooling from a change of state of water from liquid to vapor. The physical relationship between dry bulb temperature.wall area and should be fitted with impervious curtains. it is necessary to increase the rate of air movement in a house. Simple mechanical and electrical installations and elementary technology for management and maintenance favor the basic convection-ventilated unit in tropical and subtropical areas. and feed conversion are improved in heat-stressed flocks provided with a direct stream of air. Egg production. Convention-ventilated houses are economically justified in many warmclimate areas with developing poultry industries. 14 . the relatively low capital and operating costs optimize profitability. Air movement facilitates convective heat loss by the bird. Generally. This can be achieved either by installing fans in closed housing or by selecting an appropriate configuration of air inlets in relation to the dimensions of convection-ventilated units. Evaporative cooling is used to reduce the severity of heat prostration in areas where the maximum temperature exceeds 35ºC with seasonal regularity. and heat content of air is depicted in psychometric charts. When daily ambient temperatures exceed 30ºC with any frequency. To overcome high environmental temperatures. General recommendations for insulation in tropical countries include values of 2. The efficiency of this process is proportional to the velocity of the air stream and the temperature differential which exists between the bird and its surroundings. but evaporative cooling can avert losses from heat prostration even in extremely hot and humid areas. low humidity improves the efficiency of adiabatic cooling at high ambient temperature. Fiberglass blanket insulation or polyurethane panels should be coated with a reflective radiant barrier of aluminum film on the exposed outer surface and should be provided with an impervious plastic protective lining for the inner surface. mechanical ventilation is required. fertility. Although stocking density is generally low (eight to ten broilers or pullets or two to three mature breeders per square meter) compared with more advanced housing. In modern units. the area of the side opening can be controlled automatically by a thermostatically activated motorized winch with an emergency high temperature release mechanism in the event of power failure.2 m2 ºC/W (R = 7) for roof and wall structures respectively.5m2 ºC/W (R = 14) and 1. relative humidity.
wattles. 3. Although this enhances cooling.3 Management of Flocks at High Temperature The survival of birds at high temperature is strongly influenced by the volume of water consumed. commercial equipment functions with an efficiency ranging from 60 to 80%. Due to restraints associated with the process of evaporation. for 75 broilers or 50 breeders and 1 cup or nipple per cage of up to 5 commercial layers. It is essential to provide additional watering points to facilitate consumption in areas where ambient temperature exceeds 3º∫C for more than 2 hours per day. and Latin America. The low-pressure fogger nozzle produces a coarse spray. 15 .S. This system is used in the U. The simplest evaporative cooling system comprises fogger nozzles which deliver up to 8 to 10 l/hr at a pressure of 5 to 8 bar.. the U. Although systems are capable of achieving a 5ºC reduction in temperature with ambient air of 37ºC and 30% RH. The principal deficiency of the pad lies in the inherently lower efficiency of evaporation compared with the ultra-high pressure fogger. low-pressure fogger nozzles are inefficient with respect to the cooling effect relative to water consumed. Recommendations include 1 suspended drinker with a diameter of at least 40 cm. the system is susceptible to algae and mineral contamination in water. The efficiency of cooling may be enhanced by spraying pads with water from suitably placed nozzles. Pad cooling systems are used extensively in Asia. Cold water functions as a heat sink in the intestinal tract and surface evaporation from the comb. Generally. Systems require frequent cleaning and descaling and litter becomes saturated in the vicinity of the nozzles. Insulation of header tanks and supply piping is indicated if the temperature of water at the point of consumption exceeds 25ºC. where seasonally high temperatures are encountered.A.Air at 45ºC and 15% RH could theoretically be cooled to 25ºC assuming complete saturation. Nozzles are positioned in close proximity to turbulence fans to provide one discharge point for each 500 birds. where low cost is compatible with existing convection-ventilated houses. The system should only be operated when humidity is below 70% RH and with fans displacing 5 m3/ hr per broiler. and head exerts a cooling effect. Air at 45ºC and 15% RH could be cooled to a dry bulb temperature of 30ºC with an elevation in relative humidity to 60%. Modern cooling pads are composed of cellulose material in a honeycomb configuration to increase surface area.S. the coarse-nozzle system is unsuitable in Middle Eastern countries due to inefficient utilization of scarce water and blockage of nozzles by mineral contaminants in artesian water.
Exterior of breeder house showing relative size of sidewall ventilation openings. bulk-feed installation and grassed area surrounding the unit. Various lighting and feeding programs were investigated in Nigeria using medium-strain commercial layers. The use of night feeding with a reversed lighting program (18:00 to 6:00) supported a significantly higher level of egg production than conventional daytime feeding.Research on integrating lighting programs and operation of feeders for broilers has been reported from Singapore. Performance was improved in convection-ventilated housing using nocturnal illumination and feeding. which was accompanied by exposure to high diurnal temperature. mortality. This reverse diurnal lighting program produced the highest live weight at 56 days. concrete apron. and return were lower than with other combinations examined. Convection ventilated broiler house on an island subject to hurricanes necessitates concrete construction. 1. but feed conversion. Note the relative size of ventilation 16 . drainage. 2.
Equipment used to grow broiler chicks showing 20 year old overhead-filled pan feeding system and modern nipple-cup drinkers. 17 . 4. Interior of broiler house showing 2 rows of pan feeders and 4 rows of suspended plastic drinkers. Flock is uniform in size and shows feathering and pigmentation.3. consistent with health. Broilers showing signs of heat stress. 5. Flock is uniform and well feathered for age.
Modern high-density cage installation with mechanical feeding and egg collection and fan-powered ventilation controlled by electronic systems. 8. 18 . Uniformity in flocks is achieved with adequate feeding space and a supply of clean water from a closed system through nipples or cups. Chicks beneath a gas-fueled pancake brooder show good distribution consistent with satisfactory growth and feed conversion efficiency.6. 7.
Fluorescent lamps require less electrical power than incandescent bulbs. High level of dust due to inappropriate ventilation. results in respiratory stress and causes severe reactions to aerosol vaccination and viral respiratory infection. Monitoring of atmospheric ammonia at litter level using a bellows pump and chemical indicator system which is sensitive to ammonia. 11. Suspended manual feeders for cockerels. 19 . Vertical plywood boards prevent perching. Hens obtain feed from troughs fitted with male exclusion grills. Metal nest boxes with manual collection of eggs are easy to decontaminate. Breeder flock in convection-ventilated house showing ceiling insulation to reduce solar heat gain & belt-driven fan to create air movement over the flock. High ammonia level results in respiratory stress and blindness.9. 10.
14. 13.12. Obese cockerels and hens are susceptible to this condition which reduces fertility. Vent peck and disembowelment in cagehoused hens can be avoided by precision beak trimming at 7-10 days of age and adjusting light intensity to 20 lux. Pododermatitis (Bumble foot) resulting from wet litter. 20 . Keratitis (inflammation of the cornea) and conjunctivitis following exposure to high levels of atmospheric ammonia.
mycoplasmosis. 4. Salmonella enteritidis (Se) may also be transmitted vertically by incorporation of the bacterium into the albumen of the egg in the oviduct. coli and paratyphoid Salmonella spp deposited from the cloaca or nest-box litter can penetrate the shell and infect the developing embryo. 4. This situation occurs in multiage units and is a common method of transmitting salmonellosis. vaccination and hygiene. Biological transmission occurs when the pathogen multiplies in the infected host which then transmits the agent when placed in contact with susceptible flocks. Mycoplasmosis. Omphalitis and salmonellosis may be introduced into brooding and rearing units by contaminated egg-shells. wild birds. 21 .1 Transovarial Route Pathogens may be transmitted by the vertical route from hen to progeny via the egg. reoviruses and adenoviruses are transmitted in this way.1. coryza.0 PREVENTION OF DISEASE Prevention of disease in commercial poultry operations requires the application of a coordinated program of biosecurity.1. equipment. or dust carried by wind. pullorum disease (Salmonella pullorum).1.1 Mechanisms of Disease Transmission In order to develop control procedures it is important to understand the mechanisms by which pathogens are introduced into commercial poultry farms and how disease agents are disseminated among units. 4.4. 4. This form of vertical transmission results in contamination of the hatchery environment and direct and indirect infection of chicks.2 Transmission on the Egg Shell Pathogens such as E. Mechanical transmission involves transfer of a pathogen from an infected source or reservoir host to a susceptible flock by contaminated personnel. insect vectors. laryngotracheitis and pasteurellosis. rodents.3 Direct Transmission Contact between susceptible flocks and clinically affected or asymptomatic reservoirs of disease will result in infection. The following mechanisms of transmission are recognized.
Rodents carry a wide range of diseases including pasteurellosis and salmonellosis. Spread of vvND and ILT by wind has been documented in a number of outbreaks. 4. equipment or feed onto farms or movement of personnel between infected and susceptible flocks without appropriate biosecurity measures will effectively transmit disease. Pathogens may also be transmitted among flocks as a result of contaminated vaccination equipment or personnel used to administer vaccines. 4.1. 22 .1.1.4 Indirect Transmission Introduction of contaminated transport coops. In the context of Asia. and dealers in live poultry are significantly involved in transmitting disease. salmonellosis. workers.5 Dissemination by Wind Infected flocks may excrete large numbers of viruses which can be entrained in dust and moved by wind for distances of up to 5km. 4.4. Imperfectly decontaminated buildings which have housed infected flocks often contain pathogens including infectious bursal disease virus (IBDV) and Salmonella spp which can infect successive placements especially when interflock intervals are less than 10 days in duration. or the agents responsible for chicken anemia and reticuloendotheliosis. IBD.7 Feed Contamination of ingredients or manufactured feed with pathogens such as Salmonella spp. House flies transmit campylobacteriosis. West Nile and Highland J arbovirus may be transmitted by mosquitoes and spirochetosis by Argas ticks.1. Insects are responsible for transmission of various diseases. or IBD and paramyxovirus virus can result in infection of susceptible flocks. Argasid ticks (Argas spp) are vectors of spirochetosis. pasteurellosis and coccidiosis. Delivery of feed in bags requires manual handling. 4.6 Biological Vectors Wild birds are reservoirs of avian influenza and Pasteurella spp. reoviruses. Sale of live poultry involves frequent visits to farms by dealers who ignore the most rudimentary biosecurity precautions. Litter beetles (Alphitobius diaperinus) are reservoirs of a wide range of infections including Marek's disease. Pox. supervisors.8 Vaccines Contaminated poultry vaccines prepared in eggs derived from non-specific pathogen free (SPF) flocks may contain pathogens including adenoviruses.1.
composters. • Fencing of house area. • Water supply free of pathogenic bacteria. pits). feed mills. • Installations for disposal of dead birds (incinerators. • Farm service module comprising an office. A successful biosecurity program presumes an understanding of the principles of epidemiology and economics and requires teamwork to maximize benefits. storage. • Locating resources and training of personnel. Biosecurity programs require a structured approach involving the following sequence: • Planning and evaluation of programs. • For commercial egg production consider the implications of multi-age on-line units or single-age. • Appropriate location of bulk bins or secure. The following items should be considered in evaluating a comprehensive biosecurity program for a breeder or growout complex: 4. 4. • Concrete apron with a suitable water and power supply to permit decontamination of vehicles entering the farm. vermin-free storage areas for bagged feed. with secured gates. • Proximity to large lakes or waterways or migratory flyways.2 Structural Biosecurity • Fenced farm area with notices to prevent trespass. • All-weather roads within secured perimeter to facilitate cleaning and to prevent dissemination of disease agents by vehicles and footwear.2.1 Conceptual Biosecurity • Location of the complex in relation to concentrations of poultry of the same or different species. 23 . and chlorinated to a level of 2 ppm. and processing plants or packing units.2. • Control involving review of results and analytical procedures. • Location of major and minor roads and the movement of commercial and backyard poultry in relation to company facilities. • Distance among breeder and growout farms and facilities such as hatcheries. company-owned or contractor-operated facilities.2 Biosecurity Evaluating the biosecurity of ongoing operations is important in developing effective programs to prevent the introduction of disease into a complex or to limit subsequent dissemination among farms. • Implementing including erection of facilities. and change roomshower facilities.4.
unused litter and cleaned equipment should be stored in a module separated from the live-bird area of the house to prevent contamination of flocks by delivery and maintenance workers. o Controls required to prevent contact with exotic avian species. and employees. Manuals should incorporate contingency plans in the event of a deviation from normal production parameters or outbreaks of disease on company farms or in units located in close proximity to the operation. work crews and permanent and part-time employees. 4. o Storage. service personnel. concrete floors are required in both rearing and laying housing for breeders. reconstitution and administration of vaccines according to recommended route. breeding and grow out facilities.2. o Specific procedures on entering and leaving farms should be designated for managers. hatcheries. • Standardized procedures should address specific aspects of operation including: o Decontamination and disinfection of units following depletion of flocks. • Feed. In many countries with endemic salmonellosis. • Impervious apron adjacent to the door of each house and installation of drains. • Concrete floors for breeding stock at the grandparent level. 24 . authorized visitors. Manuals should be developed for appropriate levels of management including company veterinarians and health maintenance professionals. contractors. supervisors. and backyard poultry.3 Operational Biosecurity • Operational manuals should be developed for routine procedures carried out in feed mills. • Correct positioning of extractor fans to prevent airborne transmission of pathogens to flocks in adjacent houses.• Secure housing with appropriate bird and rodent proofing.
Clinical examination as part of a disease investigation requires evaluation of representative birds from a flock to determine the organ systems which are involved. Pathologists should take precautions to prevent personal infection and should exercise high standards of biosecurity to obviate transmission of pathogens. 16. Structured post-mortem examination is necessary to determine the presence of lesions characteristic of a disease in the flock. 25 .15.
• Quaternary ammonium compounds (QATs) are highly recommended to decontaminate housing.20 minutes exposure to inactive bacteria • Formalin is a corrosive and potentially carcinogenic compound suitable to fumigate eggs in purpose-designed cabinets. it is necessary to take into account the chemical characteristics. equipment. derived from petroleum distillation are cheap and effective biocides when applied to buildings and soil. or processed meat as tainting of products will occur. and the cost of application. • Organic phenols are suitable for use in hatcheries to decontaminate equipment.5 to 7. 26 .3 Disinfectants A number of compounds are available commercially.3 Decontamination of Housing and Equipment 4. 4. 4. and in hatcheries provided that an anionic detergent precedes application of a QAT.2 Decontamination Thorough decontamination is necessary to achieve effective disinfection.3.4. toxicity. These compounds should not be used in the presence of live poultry.3. functional equipment and chemical monitors. each with characteristics for specific applications. In selecting a disinfectant. Disinfection is the destruction of pathogenic organisms. • Cresols. Use of formalin requires special precautions to avoid exposure and injury to applicators who must be provided with protective clothing. eggs.5 in water free of organic matter and requires 10 . Hypochlorite is only effective over a pH range of 6. Cleaning programs require planning followed by implementation and control to ensure satisfactory preparation of surfaces for subsequent application of disinfectants.1 Definitions Decontamination is the process of physically removing biological and inorganic material from the surfaces of a building or equipment. • Chlorine compounds are widely used in processing plants and to purify water on farms.3.
motors. breeder or layer cycle will contribute to enhanced liveability and performance in subsequent flocks. and products. In the absence of national or local rules. • The interior of the house should then be sprayed with a quaternary ammonium or phenolic disinfectant solution at a concentration recommended by the manufacturer. • The interior structure and equipment should be rinsed with water and remaining detergent solution should be allowed to drain. The following procedures should be followed. Cleaning the interior should follow the sequence of ceiling. • Equipment should be disassembled and removed from the house for cleaning and disinfection. • Electrical units. internal walls. and service areas. • The floor of the house should be swept to remove residual litter.3. and switch gear should be cleaned using a high-pressure air spray and then sealed to protect installations from water damage. 4. Recommendations concerning disinfection and pest control should always conform to statutory regulations and should be designed to limit possible contamination of the environment.4. the US Department of Agriculture and the US Food and Drug Administration guidelines are recommended. and then the floor. A cresolic disinfectant can be applied to earth floors.4 Disinfection of Poultry Houses Complete depopulation of houses and decontamination of units and surroundings at the end of each broiler. Litter should be either bagged or alternatively transported in bulk from the house to a central site for composting or disposal. exterior walls. 27 .4 Public Health Considerations In most countries the use of disinfectants and pesticides is controlled by legislation which restricts the use of products to specified and approved application in accordance with manufacturers' label directions. flocks. • Litter should be graded to the center of the house for removal either manually or with a front-end loader. Detergent should be applied to the exterior in the sequence of roof. • The surface of the litter and the lower side walls should be sprayed with a 2% carbamate insecticide. • The house should be decontaminated by spraying a non-ionic detergent at a concentration recommended by the supplier. drains. rearing.
in manure. rice hulls. and insulation. in cracks in concrete slabs. • Breeder houses should be sealed and fumigated with formalin generated from heated paraformaldehyde or from a mixture of formaldehyde and potassium permanganate. electrical cables. and floor to control litter beetles. including Pasteurella multocida. Colonization can be detected by the presence of active nesting sites in attics. walls. Rats and mice are seldom seen during the day unless infestation is very heavy. • Rodent control measures should be implemented including sealing of burrows and baiting. A fog generator can also be used to distribute formalin in aerosol form through the house. (See 4. proportioned at 1%) should be used to flush water lines. Mice amplify environmental contamination and will infect poultry and products.000 dilution) or chlorine solution (1 liter of 6% sodium hypochlorite per 8 liters of water as a stock solution. under cages. or in burrows around the foundation walls. The frequency of catching rodents in traps may also be used to assess the level of infestation.5 Control of Rodents Rats and mice are significant pests in poultry facilities. water lines. sawdust) should be spread to a depth of 3 . dry substrate (wood shavings.• A 2% carbamate insecticide solution should be sprayed on the ceiling. It is emphasized that formalin is a toxic compound and is potentially carcinogenic.5 below) 4. Rodents are nocturnal and are active after lights have been turned off. Salmonella typhimurium and S. 28 . A clean. Appropriate protective clothing and respirators should be used and workers should be trained to use the compound in accordance with accepted procedures to protect health. enteritidis. Fresh droppings may be observed around the inner perimeter of the poultry house. over the floor area. Rodents are major vectors and reservoirs of poultry and zoonotic pathogens. Outdoor burrows may be closed by filling with soil and observed for reopening of entrances. A quaternary ammonium compound (1 .10 cm. (Alphitobius spp) • Equipment should be reassembled and routine preventative maintenance completed. switch gear.2. including foundations. in corners. groundnut hulls. They cause damage to building structures. • Water lines and drinkers should be drained and cleaned. Rodents serve as mechanical transmitters of infectious agents such as influenza and infectious bursal disease viruses and Salmonella and Pasteurella spp.
water. in paste. Multiple-dose compounds have a cumulative effect and will kill rodents after several feedings. Bait has to be available continuously.or multiple-dose application. All rodenticides are poisonous at various levels for poultry. chlamydiosis. Most single-dose compounds are toxic to nontarget animals and should be kept out of reach of children. Baits are available in dry or wet form. livestock. Some products kill within 1 hour. 4. in powder mixed with grain. bait should be available in both feed and water.6 Control of Free-Living Birds Free-living migratory and resident birds serve as reservoirs and disseminators of numerous infections of commercial poultry. and other feed sources must be removed. and pasteurellosis. avian influenza. or in water. poultry. in wax. appropriate management and sanitation.A continuous integrated program to control rodents includes rodentproofing of buildings. pets. in pellets. A single-dose rodenticide will kill rodents after one feeding if an adequate amount is consumed. and manufacturer's label instructions should be strictly followed. 29 . Rodenticides are available for single. The rate of rodent kill depends on the type of rodenticide and the dose consumed. Only extreme situations call for the use of a single-dose rodenticide with high toxicity. but most available anticoagulant rodenticides require 4 to 7 days after ingestion. These include Newcastle disease. duck viral enteritis. micro-encapsulated. Bait should be offered at stations located in the activity zone of rodents. Preventing access to feed. and livestock. elimination of nesting places. in the routes between the nesting site and the common food source. Caution in the use of rodenticides is required. and shelter is an important part of a rodent-control program. The following precautions can be applied to reduce the probability of infection: • Water obtained from lakes or ponds on which waterfowl accumulate must be filtered and treated with chlorine to a level of 2 ppm. salmonellosis. and humans. and chemical and nonchemical elimination. Chemical methods to control rodents include bait and tracking powder. For maximum effectiveness. and at the entrance to houses and near active burrows.
2.10-anthraquinone. which induces an irritation of the crop as a result of ingestion of minute quantities following preening. farms and processing plants. This includes netting over air inlets. gantries and structures where resident pigeons and sparrows congregate. Microbiological contamination including fecal coliforms and viable Newcastle disease and avian influenza viruses can result in infection of flocks.5 to 7. For effective treatment the pH of water should be adjusted within the range of 6. Since birds can differentiate between treated and non-treated surfaces by visualizing the UV spectrum of 9. Water lines can be flushed and decontaminated with solutions as indicated in Table 4.5.10-anthraquinone) can be applied as a paint suspension to roof areas. A commercial product. 30 .7 Quality of Water Water supply for farms and hatcheries should be obtained from a municipal source which is filtered and chlorinated or from a deep (+50m) cased well or from a filtered and treated source from a dam or river. Standards for mineral and microbiological quality are shown in Table 4. and screen doors.• Buildings housing flocks and warehouses should be bird-proofed.1. 4. Water containing mineral impurities can affect skeletal integrity. intestinal function and detract from optimal growth and feed conversion efficiency. exhaust openings. Avipel® will repel birds by a process of aversion to the compound. Chlorine can be added to drinking water at a level of 2 ppm using either sodium hypochloride or a gas chlorine installation. resident populations of potential reservoirs of infection are displaced from critical areas in feed mills. Avipel® (9.
5 mg/l 50 mg/l TABLE 4. 31 .3 mg/l 0.2 PREPARATION OF SANITIZER SOLUTIONS TO FLUSH WATER LINES SUPPLYING NIPPLE & BELL DRINKERS Concentration of Stock Solution 50 ml/10 l 500 ml/10 l 1500 ml/10 l 150 ml/10 l Additive 35% hydrogen peroxide 20% sodium hypochlorite (commercial) 6% sodium hypochlorite (domestic) 18% iodine complex Stock solution to be metered at a dilution rate of 1% into water system using a proportioner.1 STANDARDS OF WATER QUALITY FOR POULTRY Average Level 0 CFU/ml 0 CFU/ml 6.8 .002 mg/l 0.TABLE 4.0 .0 150 ppm Component Bacteria Total bacteria Coliform bacteria Acidity and hardness pH Total hardness Naturally-occurring elements Calcium Chloride Copper Iron Lead Magnesium Nitrate Sulfate Zinc Sodium 60 mg/l 15 mg/l 0.8.2 mg/l 0 15 mg/l 10 mg/l 125 mg/l 5 mg/l 30 mg/l 250 mg/l 0.6 mg/l 0.6 60 .02 mg/l 125 mg/l 25 mg/l 250 mg/l 1.7.200 ppm Maximum Acceptable Level 100 CFU/ml 10 CFU/ml 6.
19. Backyard poultry and gamefowl serve as reservoirs for a wide range of infections which can impact the health and profitability of commercial poultry.17. Neglecting maintenance will result in rodent infestation. 18. Inadequate change room facilities may contribute to the introduction of infection to farms and hatcheries. 32 .
21. Wet markets are a source of infection and special precautions should be taken to avoid introduction of disease onto farms by live bird traders. Accumulation of debris and discarded equipment encourages breeding of rodents. 33 .20. is cost efficient and consistent with accepted standards of biosecurity. 22. Bulk delivery of grain reduces manual handling.
Manual handling of feed bags by workers may result in introduction of infection onto farms. 34 .23.
This interference phenomenon is important in timing the first "priming" dose of vaccine which stimulates immunity against IBD. Vaccination programs should be based on the following considerations: • Diseases prevalent in the area of operation. High maternal antibody is reflected in uniform and proportionally elevated antibody levels (titers) in progeny. A waning in titer occurs over the succeeding 1-3 weeks. • Flock placement programs.0 5.1 VACCINATION AND MEDICATION General Principles Vaccination involves the administration of a specific antigen to stimulate the immune system to produce homologous antibodies against viral. Circulating antibodies derived from the hen increase from day 1 to day 3 as yolk is absorbed. The dilemma facing poultry health professionals in developing vaccination programs for chicks is to specify the age of administration relative to the level of maternal immunity. • Immune status of parent-level stock in relation to maternal antibody transfer. If the initial vaccine is administered too early in relation to the decline in maternal 35 . Maternal antibodies (MABs) are transferred from the serum of the hen via the yolk to the chick. Low and variable immunity in parent flocks is associated with early susceptibility of chicks. and protozoal diseases. according to a decay rate characteristic for the antibody. or by vaccination (artificially acquired immunity). • Risk of exposure. Passively acquired maternal antibody may protect progeny against post-hatch exposure to certain pathogens for up to 2 weeks.2 Significance of Maternal Antibody in Relation to Flock Protection Maternal antibody (parental immunity) is stimulated in breeding stock in response to exposure to pathogens (naturally acquired maternal antibody transfer). High levels of maternal immunity often inactivate mild attenuated vaccine virus administered to chicks. bacterial. 5. • Availability of specific vaccines.5. • Intensity and consequences of adverse vaccine reaction. IB and ND. • Cost of acquisition and administration of vaccines. • Cost to benefit ratio associated with vaccination taking into account the risk of infection and financial loses from disease.
Administration of a mild IBD vaccine will stimulate immunity due to waning of maternal antibody. Administration of mild IBD vaccine will be ineffective due to interference by high maternal antibody (mab) level.1 RELATIONSHIP OF MATERNAL ANTIBODY AND VACCINATION IBD Antibody Level 3000 waning of mab 2000 rise in titer following vaccination or challenge 1000 Antibody level corresponding to susceptibility to field IBD 0 A 7 B 14 C 21 Age Days A. (Figure 5. Flock will be susceptible to field IBD challenge at this time. B. field challenge of susceptible birds will occur. C.antibody. Subsequent administration of intermediate IBD vaccine will reinforce immunity and raise circulating antibody level. 36 . If the initial vaccination is delayed. At this age exposure to vvIBD will result in infection due to the ability of virulent field virus to overcome maternal antibody protection. the chick will not be protected.1) FIGURE 5.
Tables 5. Avian health professionals are advised to consult with local specialists and suppliers of vaccines to develop appropriate programs. Although it is not possible to provide immunization protocols to suit specific circumstances. Table 5. The administration of oil emulsion vaccines to boost immunity is required to ensure satisfactory transfer of maternal IgM antibody to progeny. and environmental and management factors which may induce adverse vaccine reaction. Table 5. Intensive vaccination programs are required to protect broilers. and ages of administration. which are housed at high levels of biosecurity. Various strategies have been adopted in the US and Europe to immunize broilers. sequence. High uniform levels of maternal antibody are attained in breeders using attenuated live vaccines as "primers" followed by inactivated subcutaneous or intramuscular oil-emulsion "boosters" prior to onset of lay. the risk and consequences of field infection. Administration of vaccines in drinking water or by spray are repeated successively during the growing period. For young breeder flocks. The principle of using a mild attenuated vaccine to establish immunity is emphasized. Table 5.1 represents a comprehensive program to protect imported breeding stock from a wide range of diseases prevalent in an area of operation. 37 . Flock application at day old with attenuated IB/ND is followed by one or more "boosters" during growout. This program should only be considered as a general guide to the types of available vaccine.2 represents a comprehensive program to protect broilers in areas with both endemic vvND and vvIBD. routes.3 represents a comprehensive program to protect commercial laying flocks against the usual range of diseases endemic in Asia.3 illustrate practical programs which integrate vaccination against the diseases that occur commonly in Asia. breeders and pullets against exotic and catastrophic diseases including very virulent (vv) pathogenic IBD and vvND.1 to 5. the initial doses of vaccine may be delayed until 7-14 days of age to ensure active priming of the immune system.Other factors of importance in devising vaccination programs include the antigenicity ("strength") of the vaccine virus.
in cabinets for mass-administration of aerosol vaccines to day old chicks. 5. to administer inactivated aqueous and emulsion vaccines to replacement pullets or mature stock.5. • Drinking water administration can be implemented at low cost but is of limited effectiveness against some infections. 38 . using a manual or automatic syringe. requiring handling of individual chicks. • Post-hatch spray vaccination. • Intramuscular injection. • Aerosol administration. are applied in hatcheries and during brooding of chicks. Over-reliance on medication is both expensive and has negative flock and public health implications. The administration of drugs is generally a last resort to salvage the value of a flock and to reduce losses following infection.3 Administration of Vaccines Various methods of administering vaccines are used commercially. Medication should be used only after implementing accepted methods of prevention and control of disease. • Wing-web stab to administer live vaccines by the percutaneous route directly to each bird. The availability of drugs varies according to regulations in a specific country. • Eye drop and intranasal routes. Important considerations which contribute to effective medication include: • The diagnosis should be established by isolation and identification of the pathogen by microbiological or other laboratory procedures. • In ovo vaccination at 18 days of incubation using the patented Embrex InovoJect® system and alternatives. The actual administration of vaccines should be monitored by submission of serum specimens to a diagnostic laboratory for titer assay using ELISA or other acceptable technique. using a knapsack or electric sprayer to deliver vaccines to flocks as a coarse spray. including. It is emphasized that appropriate control over the reconstitution of live vaccines is required to ensure potency.4 Medication Antibiotics and chemotherapeutic compounds are administered to flocks to treat outbreaks of disease. rearing stock and breeders. to administer either live or inactivated emulsion vaccines to chicks. • Subcutaneous injection.
breeding stock may be infected with a vertically transmitted disease. 24. biosecurity or vaccination exist. Alternatively. other livestock and consumers. by assay of compounds in feed or water. • Response to medication should be monitored in relation to clinical improvement and.2. Frequent or continuous administration of medication will result in emergence of drug resistant pathogens which will affect poultry. deficiencies in management.2) • Statutory withdrawal periods should be followed before the sale of live birds or processing to prevent drug residues in food products. Hatchery vaccination using an automatic injector.• Pathogens should be shown to be susceptible to the selected drug using appropriate microbiological sensitivity assays. (Figure 5. • Medication should be administered in accordance with the manufacturer's dose recommendations and for the suggested duration of treatment. • Medication should only be initiated in anticipation of a positive benefit to cost ratio projection based on previous clinical response and a projection of losses. 39 . A schedule of therapeutic drugs and appropriate dose rates is depicted in Annex 41. It is emphasized that if routine medication is required for successive flocks. where possible.
(Courtesy Intervet) 26. Vaccination by the wingweb stab route using a rotating carousel to hold birds.25. (Courtesy Intervet) 27. Vaccination of immature breeding stock with an oil emulsion. Administration of an oil emulsion vaccine using a manual syringe. (Courtesy ScheringPlough) 40 .
(Courtesy Intervet) 29. Vaccination by the intranasal route. Cleaning of drinkers prior to administration of vaccine by the oral route.28. 41 .
FIGURE 5.000 birds with a daily consumption of 100 ml/bird Total consumption of water over 5 days Antibiotic consumed Cost of antibiotic therapy for flock Value of bird Number of birds to be "saved" as a result of therapy to break even Reduction in mortality rate to break even Assume mortality reduced by Benefit : Cost ratio for therapy = 5000 l = 5 = $500 = $1 = 500 = 5% = 800 birds = 1. 10.2 EVALUATION OF ANTIBIOTIC THERAPY Consider antibiotic product with a concentration of 7% active ingredient @$100/liter Suggested dose rate of 1 ml/liter of drinking water Flock size.6 42 .
H120 Multivalent ND.H120 *Salmonella typhimurium (mutant) ND HB-1 IBD (intermediate) ND HB-1 Reovirus Live ND oil emulsion AE + Fowl Pox *Avian influenza emulsion IB .1 COMPREHENSIVE BREEDER VACCINATION PROGRAM Vaccine or Operation Marek's disease. IB. hatchery Aerosol spray Eye drop Eye drop Subcutaneous Drinking water Subcutaneous Eye drop or Drinking water Eye drop Drinking water Intranasal Drinking water Aerosol spray Wing web Subcutaneous Wing web Intramuscular Drinking water Wing web Drinking water Subcutaneous Wing web Drinking water Subcutaneous Intramuscular Drinking water Aerosol spray Subcutaneous Aerosol spray Aerosol spray Age 1 day 2 days 5 days 7 days 7 days 10 days 14 days 19 days 21 days 24 days 5 wks 5 wks 6 wks 8 wks 10 wks 12 wks 15 wks 17 wks 18 wks 20 wks 21 wks 32 wks 42 wks (optional) 55 wks 65 wks (optional) *where prevalent.H120 Pasteurella live ILT EDS Pasteurella live Deworming Multivalent ND. Reo emulsion *Avian influenza emulsion Transfer Deworming NDHB-1 + IB . mycoplasmosis and coryza if prevalent in the area of operation. Specific modifications will be required to the program to protect against fowl typhoid. No antibiotic should be administered within one week before or after live mutant S.TABLE 5. IBD. typhimurium vaccine. IB. Rispens strain *Salmonella typhimurium (mutant) ND HB-1 IBD(mild) ND oil emulsion Coccidiosis oocysts Beak trim Reovirus Live (mild) IBD (Intermediate) ND HB-1 IB . Abbreviation AE Avian encephalomyelitis (epidemic tremor) EDS Egg drop syndrome ND Newcastle disease IBD Infectious bursal disease ILT Infectious laryngotracheitis ND Newcastle disease 43 . IBD. Reo emulsion NDHB-1 + IB H120 NDHB-1 + IB H120 Route Subcutaneous.
2 COMPREHENSIVE BROILER VACCINATION PROGRAM Vaccine Marek's disease. HVT & SB 1 combination *Salmonella typhimurium (mutant) ND oil emulsion ND HB-1 IBD (mild or intermediate) IBD (intermediate) ND HB-1 IB H120 *ILT IBD (intermediate) ND HB-1 ND HB-1 Route Subcutaneous Aerosol spray Subcutaneous Aerosol spray Eye drop or Subcutaneous Drinking water Drinking water or Aerosol spray Drinking water Drinking water Drinking water Aerosol spray Aerosol spray Age (days) 1 8 10 12 14 16 21 30 (optional) * where prevalent Abbreviation IB IBD ILT ND Infectious bronchitis Infectious bursal disease Infectious laryngotracheitis Newcastle disease 44 .TABLE 5.
*if required in area of operation. and potentially exposed to a high risk of infection.TABLE 5. Abbreviation AE IB IBD ILT ND Avian encephalomyelitis (epidemic tremor) Infectious bronchitis Infectious bursal disease Infectious laryngotracheitis Newcastle disease 45 . ND IB *Avian influenza emulsion ND .IB combination Transfer Multivalent inactivated EDS. hatchery Drinking water or Eye drop Aerosol Subcutaneous Subcutaneous Eye drop Drinking water Drinking water Drinking water Drinking water or Aerosol spray Drinking water Intramuscular Wing web stab Drinking water Drinking water Subcutaneous Drinking water or Aerosol spray Intramuscular Intramuscular Age 1 day 5 days 10 days 14 days 20 days 24 days 30 days 6 wks 7 wks 10 wks 12 wks 16 wks 30 wks Small scale operations with available labor.IB combination (and at 12 wk intervals thereafter) If required: Fowl typhoid at 7 wks or: Coryza bacterin at 7 wks and 14 wks Route Subcutaneous.3 COMPREHENSIVE VACCINATION PROGRAM FOR COMMERCIAL EGG PRODUCTION FLOCKS Vaccine or Operation Marek's disease HVT & SB 1 combination *Salmonella typhimurium (mutant) ND HB-1 *ND oil emulsion *IBD oil emulsion *IBD mild strain IBD intermediate strain *Salmonella typhimurium (mutant) IB-HI20 ND IBD intermediate strain *Avian influenza emulsion Avian pox and AE ILT ND .
The facility must meet the following requirements: • Perimeter of the site must be surrounded by a chain-link fence buried to a depth of 0. gas tanks.1 6. Rigid separation of the potentially "contaminated-outside" and the inner high security bird area should be maintained. 6. • All equipment.0 SPECIAL PROCEDURES RELATING TO CONTROL OF DISEASES IN POULTRY OPERATIONS Control of Disease in Multiplier Breeder Farms Suppliers of breeding stock in the USA and Europe maintain flocks free from salmonellosis. • No vehicles or equipment should be allowed within the farm area from the time of delivery of flock until depletion. • A 1 m wide strip on either side of the fence must be mowed so that any rodent or vermin activity can be detected. such as feed bins. mycoplasmosis.6. • All openings in the perimeter fence must be secured. requiring service by non-farm personnel must be located adjacent to the perimeter fence.1. vaccination. Design features should include: 46 . Breeder farms should be operated on an all-in-all-out basis preferably with absolute separation of rearing and laying flocks. resulting in suboptimal production and transmission of disease to progeny. • A 3 m wide area around building perimeters must be kept free of all vegetation other than mowed grass to inhibit rodent and wildlife activity. • Entry of personnel into each single-age flock should be through a shower module and require a complete change of clothing. and many other vertically transmitted diseases including specific retroviruses. spraying. at the grandparent or parent level in the country of operation may lead to infection of breeding flocks. • Small tools and equipment for mowing. Deficiencies in biosecurity.3 m to exclude burrowing wildlife and should be topped with barbed wire to prevent unauthorized entry.1 Structural Biosecurity Multiplier breeder farms should be at least 3 km from any commercial or backyard poultry. • Buildings housing flocks must be constructed to allow complete decontamination after depletion of flocks. electric and water meters and stand-by plants. and weighing must remain inside the fence during the life of the flock.
If a production unit has birds of more than one age.1. movement must proceed from the youngest to the oldest flocks to limit cross-transmission of pathogens. and other wildlife. and consignments of feed should be assayed monthly for bacterial and fungal pathogens. coops and vehicles. 6. Ideally. nets. including ceilings and side walls should be cladded with an impervious material such as galvanized steel or aluminum that can be easily cleaned and disinfected. showering of personnel. should be constructed of concrete blocks. 6. must be thoroughly cleaned and disinfected after use. supervisors or managers should visit only one production facility. Feed ingredients. • The interior surfaces of the building. • Concrete floors should be smooth-troweled and sloped to lateral drains. This requires examination of each load of floor and nest litter for insects or foreign material. 47 . rodents.2 Operational Biosecurity Disease-surveillance procedures must be followed for all consumables used or introduced onto the site. Moving flocks between farms can potentially expose birds to disease. Some integrators operate placement programs which house flocks from day old until the end of the egg-production cycle. and bacteriological cultures should be performed to monitor the effectiveness of decontamination.1 Structural Biosecurity The general considerations relating to construction of houses as outlined for breeding facilities should be followed.• Perimeter walls.2. such as a farm or hatchery each day. site-clothing should be followed. Movement of workers and crews among farms should be limited during each working day. • All openings into the building should be screened to prevent access of free-flying birds.2 Control of Disease on Commercial Broiler Farms 6. such as ramps. and provision of clean. Metal personnel doors and installation of wire mesh screens over windows are recommended. All equipment. 70 cm high. Split-cycle rearing and laying is recommended. Complete decontamination of equipment. All equipment should be visually inspected. This system has disadvantages relating to capital cost and management.
The installation of bins (silos) for bulk-delivery of feed is strongly recommended to reduce the risk of introduction of disease associated with manual handling of feed bags. These are adapted from the general biosecurity recommendations and the management guidelines issued by breeders. The intensity of disease prevention measures depends on the risks and consequences of infection. It is necessary to transport broilers intended for sale to a remote site for selection and purchase by dealers.6. 48 .2. This approach to live bird sales allows complete depopulation of farms with realistic interflock intervals of at least 10 days.2 Operational Biosecurity It is impossible to maintain adequate biosecurity when live birds are marketed directly from growing farms. Appropriate programs of disease detection and vaccination should be implemented.
Isolated breeder farm in a rural U.) 31.S. 49 . location remote from nearest public road. (Courtesy of Ross Breeder Inc. The entire farm is surrounded by secure fencing and a high level of biosecurity is imposed to prevent introduction of disease which could be spread vertically to progeny.30. Maintaining multi-age farms or establishing units in close proximity creates problems relating to control and eradication of chronic diseases such as mycoplasmosis and coryza. Materials used for construction are incompatible with disinfection. 32. Well-ventilated convection house using indigenous materials suitable for broiler growing.
Delivery vehicles should be disinfected before entry to farms to avoid introduction of pathogens..000 birds/week. 35.. Pasteurella spp. 34. Installation of mechanical washer to decontaminate coops before return to farms. 50 .33. Processing plant has a throughput of 100. and other infectious agents. Litter beetles (Alphitobius diaperinus) serve as reservoirs of Marek's disease virus. Salmonella spp.
effective programs to suppress vermin should be an integral component of a disease prevention program. bulk-delivered feed is recommended to obviate manual handling and delivery in bags. Movement of personnel should be controlled. • Due to the low level of mechanization in laying units in Asia. • Since rodents are reservoirs of salmonellosis. • Routine disease monitoring is necessary. and where possible.1 Operational Biosecurity • It is suggested that small-scale egg-production units in Asia should be operated on an all-in-all-out basis with separate rearing and laying units. Plastic flats should be used. 51 . • Appropriate vaccination programs should be implemented to protect flocks against challenge. In view of the high investment in facilities and flocks.6. Culled hens should be transferred from the production unit to a remote site for sale to live-bird dealers. If this is not possible. pullets should be obtained from a source known to be free of vertically transmitted infections or diseases characterized by a permanent carrier state such as coryza.3. pasteurellosis and Marek's disease. especially when products are distributed through dealers. which can be decontaminated at the point of entry to the farm. • Care should be exercised in using recycled egg packing material. Exposure to disease will lower egg production and reduce quality following transfer to laying units. relatively large numbers of laborers are employed to feed flocks and collect eggs. salmonellosis or laryngotracheitis. it is recommended that appropriate biosecurity procedures should be implemented. Change-room and shower facilities are required and protective clothing should be provided to prevent introduction of disease onto farms by workers. Procedures include postmortem examination of dead birds when mortality exceeds standard levels and periodic serum antibody assays to determine the immune status of flocks. Laborers invariably have contact with backyard chickens which are reservoirs of disease.3 Control of Disease in Commercial Egg Production Units 6.
52 . 37. Simple single-tier layer cage installed in open-sided house incorporating manual feeding and a trough drinker. 38. The undeveloped comb of a culled pullet. These inexpensive systems are extensively used in Asia. but labor input is high and the system is associated with problems of manure disposal and houseflies. Well developed comb of a healthy 25 week old Leghorn hybrid hen.36.
positive pressure should be maintained in egg setter bays. A log book should be kept for entry of visitors or deliveries to the hatchery.6. processing. 53 . shower. • Adequate laundry. • Air intakes should never draw air from the vicinity of an exhaust duct. Where possible. which are graded and decontaminated by spray or fumigation on the breeder site.4. chick boxes. Facilities should be provided to disinfect all entering vehicles. To prevent mold growth. Potentially contaminated areas are the chick takeoff. • All vehicles should be disinfected before entering a hatchery. To prevent movement of air from "dirty" to "clean" areas. all egg flats.2 Operational Biosecurity • A dedicated egg-collection vehicle should be used for fertile eggs. in accordance with the recommendations of suppliers of chemicals and equipment. washing of chick boxes and trays. One central point of entry adjacent to the change room should be designated. 6. Work flow should permit separation of potentially contaminated and "clean" areas. • An appropriate cleaning and disinfection program should be followed. plastic egg flats and packaging material should be color-coded to the farm of origin. these should not be reused. and all entrances to the building should be located inside the fenced area.4 Control of Disease in Hatcheries 6. • Hatcheries should be designed with a floor plan. and metal boxes should be thoroughly dried after disinfection. • Reusable plastic egg trays can be used to collect commercial broiler eggs but should be cleaned and disinfected after each use. • Installations should be capable of adequately cleaning and disinfecting all setter and hatching trays. trays. ventilation system and interior finishes conforming to accepted standards of hygiene. Hatchery design should allow for future expansion and incorporate provision for drainage. and change room facilities for staff and visitors should be available and used routinely. and chick dispatch area.4. and washing areas. recording date and time and the previous farm or site visited.1 Structural Biosecurity • Access to the hatchery and any associated buildings should be restricted. disposal of waste. Door seals should prevent crosscontamination by air movement. The facility should be supplied with chlorinated water. cold room for eggs. The facility should have a secure fence. and egg flats used in the hatchery. Egg-delivery vehicles should be decontaminated and fumigated daily. Since fiber trays and cardboard boxes cannot be cleaned and disinfected.
Vaccination equipment should receive special attention according to manufacturers' recommendations. Setter rooms should be disinfected daily under supervision and inspected to ensure compliance with standard procedures. Procedures should specify disinfectants. Correlations between the microbiological test results. Routine fogging or fumigation is necessary to prevent aspergillosis. with appropriate action to prevent cross-contamination. Procedures should be reviewed and updated as necessary. and the water supply. and surface swabs. and chick livability should guide the choice of disinfectants and dilution rates. Chick boxes should be cleaned on return to the hatchery. • At the end of each hatching day. hatchability. chick-processing rooms. the chick-processing room should be cleaned and disinfected. Routine tests should include incoming eggs. the egg room. exposure of media plates to air. hatchers after disinfection.5% increase in first week mortality. including all work surfaces and installations.• Single-stage setters should be cleaned and disinfected after each transfer. vehicles. Only properly trained personnel should clean and apply disinfectants. and the method and frequency of application. Broken eggs should be removed from setters daily. exhaust ducts. agar gel impression disks. 54 . centrifugal air sampling. setters. Setter racks should be cleaned and inspected before return to the breeding farm. • The hatchery sanitation program should be incorporated into a hatchery manual. • Chick-delivery vehicles should be decontaminated daily. • Hatchers and hatching equipment should be cleaned and disinfected after each take-off. • Quality control procedures include examination of hatchery fluff. hatcher rooms. setters rooms. concentration. • Routine monitoring of cleaning and disinfection should be carried out and appropriate remedial action should be taken if the prevalence of omphalitis or aspergillosis results in a 0.
39. Setter bay in small hatchery showing high standards of surface finishes consistent with acceptable hygiene and decontamination. 55 .
cobalt .calcium .iron .phosphorus as phosphate .lysine . • Biological potency of specific vitamins or availability of minerals may 56 .0 7.copper .magnesium . and immune response.selenium . • Energy • Crude protein • Essential amino acids with specific reference to.tryptophan .2.iodine as iodized salt • Vitamins Nutrient Deficiencies 7. linear programming is used to develop formulations containing the most critical nutrients.7. liveability.1 NUTRITION OF CHICKENS AND DIETARY DEFICIENCIES Establishing Nutritional Specifications Modern broiler.1 Causes of Nutrient Deficiencies • Diets may be erroneously formulated. . Generally. feed conversion. Suppliers of stock provide printed management guides incorporating nutrient specifications appropriate to the various ages and types of poultry. These include.sulphur as sulfate • Micro Elements .chlorine as chloride . Nutritionists satisfy dietary requirements by blending available ingredients into diets on a leastcost basis. breeder and egg-production flocks require diets balanced in essential nutrients to achieve optimal reproductive efficiency.cystine .2 7.methionine .sodium .zinc .manganese .potassium .threonine • Fats and essential fatty acids (linoleic acid) • Macro Minerals .
Destruction of nutrients can occur in feed due to oxidation. essential fatty acid deficiency will result in 57 . both egg size and egg numbers will be reduced. feed conversion efficiency. mature birds will lose weight and hens will show a decline in both egg size and egg numbers. Under conditions of elevated temperature.2. Under conditions of feed restriction or extreme competition. immune response and reproductive efficiency.2. 7.2.4 Fats Suboptimal levels of essential fatty acids including linoleic and linolenic acid will depress egg size in high-producing hens. In the case of mature flocks. The effect of restricting energy intake will be exacerbated by low environmental temperature or improper management of brooding and ventilation systems during the early growth phase. Male breeders will become infertile. Deficiencies in energy and essential amino acids will exacerbate the effects of viral malabsorption syndrome and intestinal damage caused by coccidiosis or endoparasites. Chemical antagonists in feed may increase the nutritional requirements of nutrients. 7. Flocks deprived of energy will show increased susceptibility to infection. It is emphasized that suboptimal levels of essential amino acids will not result in any specific clinical sign or lesion other than a failure to attain accepted production standards. Growth rate of immature stock will be depressed. Methionine deficiency in diets containing maize and soybean meal will result in a low growth rate.3 Deficiencies of Proteins or Amino Acids Low protein intake will depress growth rate. A deficiency in lysine may occur in wheat and maize-based diets and will result in depressed growth rate and feed conversion efficiency in broilers.2 Low Energy Intake Most poultry will compensate for low energy density by consuming a greater quantity of feed. Deficiencies may occur due to deletion of specified ingredients or supplements from rations. 7. Under commercial conditions multiple deficiencies often occur and signs and lesions associated with suboptimal intake of a specific nutrient may not be clearly defined. The nutrient quality of ingredients may be depressed by excess moisture. mold contamination or inappropriate processing.• • • • be sub-optimal.
carcass meal. vegetable oils and animal tallow will allow oxidative rancidity to occur. with hemorrhage into the body cavity. sodium bicarbonate as a buffer in a hydrated aluminum silicate carrier. The initiation of oxidative rancidity characterized by free radical formation is stimulated by high ambient temperature. 58 . ataxia (inability to stand). and the presence of metal catalysts in storage tanks.5 Oxidative Rancidity Failure to stabilize ingredients such as fishmeal.2.6 Vitamin Deficiencies Deficiencies of vitamins may occur following inappropriate formulation. the use of impotent commercial preparations or destruction of nutrients in feed by oxidation. These compounds are combined with a chelator such as citric acid.2. Since vitamin A is concerned with the integrity of respiratory and gastrointestinal mucosa. Antioxidants can also be added to specific ingredients such as fishmeal or animal byproduct meal in liquid form during manufacture. Most commercial antioxidant additives for feed use contain ethoxyquin. Autoxidation is prevented by supplements which chelate metallic ions and scavenge and inactivate free radicals. Ingredients containing high levels of saturated fatty acids are susceptible to this process which yields toxic peroxide free radicals which damage cell membranes and overwhelm the inherent biological antioxidant systems at the cellular level.degeneration of the liver and possibly rupture of the capsule. Antioxidant products are required for ingredients containing in excess of 10% fat. (Fatty liver syndrome) 7. prolonged storage of diets. The significant deficiencies encountered in commercial poultry production include. Addition rates to diets at levels equivalent to 125 ppm ethoxyquin are suggested. • Avitaminosis A Chicks will show poor growth and feathering and in advanced cases. Laying hens subjected to avitaminosis A will show a deterioration in internal egg quality and a high prevalence of blood spots. xerophthalmia ("dry eye") and chronic purulent conjunctivitis (accumulation of yellow caseous material beneath the eyelids). Fertility and hatchability of breeders will be adversely affected. coli and other bacterial infections and will be more severely affected by endoparasites and coccidiosis. and/or butylated hydroxy toluene. 7. rice bran. flocks subjected to avitaminosis A will show a high prevalence of E.
• Vitamin D3 (Cholecalciferol) Deficiency A deficiency in vitamin D3 will lead to rickets in immature flocks. Rickets can be confirmed by histological examination of the proximal end plate of the tibia and parathyroid gland tissue. Transudative diathesis can be partly reversed by supplementation of diets with adequate quantities of selenium. Swelling of the joints is noted together with depressed growth rate and poor feathering.3 ppm). The presence of free radicals will result in destruction of vitamin E both in the feed and in vivo. a deficiency of vitamin D3 results in osteomalacia characterized by decreased skeletal density. preferably in the organic 59 . Encephalomalacia occurs in chicks fed diets in which vitamin E has been destroyed by oxidative rancidity. In advanced cases urate deposit on the viscera (visceral gout) is observed at postmortem examination. Transudative diathesis occurs in chicks fed diets deficient in vitamin E or containing free radicals. Both immature and adult flocks will show kidney degeneration and the accumulation of urate in the ureters.1 to 0. In mature laying and breeding stock. costochondral (rib to spine) junctions are enlarged and the end plates of the long bones are irregular due to defective mineral deposition required for osteogenesis (bone formation). Affected flocks show a gradual decrease in egg production and a marked deterioration in shell quality. (0. • Vitamin E Deficiency Vitamin E is required in complex biochemical functions. Transudative diathesis results from degeneration of the endothelium (lining of the blood vessels) resulting in leakage of plasma into surrounding tissues. Ascending mortality is associated with paresis and paralysis in caged hens which are unable to stand to feed and drink. The characteristic change comprises squamous metaplasia. On post-mortem examination decreased skeletal density is evident. Vitamin D3 deficiency results in gross enlargement of the parathyroid glands. Affected birds aged 4 to 7 weeks show a disinclination to walk. in which normal columnar epithelial cells regress to multiple layers of flattened cells. Three specific conditions occur in young chickens.Diagnosis of avitaminosis A can be confirmed by microscopic examination of the trachea and oral mucosa.
Subcutaneous hemorrhages are noted on the head and beneath the wings of affected birds. and anticoagulant rodenticide toxicity.30 seconds to values exceeding 5 minutes. the ventriculus (gizzard) and myocardium (heart muscle). Organophosphate toxicity which causes incoordination and death preceded by convulsions is usually peracute in onset and involves the entire flock. Malacia (softening) of the brain is evident. The effect of avitaminosis E is exacerbated by concurrent deficiency of sulphur-containing amino acids and selenium. Recently. Flocks showing nutritional encephalomalacia will respond to administration of water dispersable vitamin E and stabilization of diets with antioxidants and supplementary vitamin E. On post-mortem examination sub-serosal hemorrhage is evident. Affected birds do not recover. arenavirus infection has emerged which leads to hypoglycemia which results in recumbency and tremors. avian encephalomyelitis (epidemic tremor). Encephalomalacia is the most commonly encountered condition associated with avitaminosis E due to a deficiency or in vitro destruction in tropical countries. The differential diagnosis of ataxia in chicks includes avitaminosis A. The condition can be diagnosed by determining the prothrombin time which is delayed from a normal 20 . The condition can be confirmed by histological examination of brain tissue from affected birds. • Vitamin K Deficiency This condition occurs in caged flocks fed rations deficient in vitamin K. incoordination. 60 . Muscular Dystrophy occurs in the skeletal muscles.(selenomethionine) form which is more available than inorganic sodium selenite. mycotoxicoses. and terminal recumbency with cycling motions of the legs. Infected birds demonstrate ataxia. The characteristic lesion comprises punctate hemorrhages within the cerebellum and occasionally the cerebrum. Onset is at approximately 10 . thiamine and pyridoxine deficiencies.20 days of age and may result in the death of up to 10% of the flock. Differential diagnoses for vitamin K deficiency include hemorrhagic syndrome.
osteomalacia may occur. Chicks from deficient flocks have abnormal development of down feathers. • Calcium and Phosphorus Deficiency In immature flocks a deficiency of either calcium or available phosphorus or an imbalance in these nutrients will result in rickets. to diets. Affected flocks will demonstrate low growth rate and poor feathering. In breeding flocks. and is referred to as "club foot" or "curled toe paralysis". Calcium and phosphate deficiencies may be diagnosed by histological examination of bones and the parathyroid gland. The principal sign of thiamine deficiency in 10 to 20 day old chicks comprises incoordination and an abnormal retraction of the head ("star gazing").30 days. pyridoxine and folic acid can be reproduced under experimental conditions. bone ash determinations. Histological examination of the major peripheral nerve tracts will show myelin degeneration. These changes also occur with pantothenic acid deficiency and reoviral malabsorbtion syndrome. • Biotin Deficiency Affected flocks demonstrate poor growth and feathering and elevated mortality.• Vitamin B1 (Thiamine) Deficiency Avitaminosis occurs as a result of failure to add thiamine to vitamin premixes or occasionally as a result of excessive addition of the anticoccidial. • Vitamin B2 (Riboflavin) Deficiency This condition is characterized by rotation of the legs in chicks aged 10 . • Manganese Deficiency Manganese deficiency leads to chondrodystrophy which results in deformation of the distal tibiotarsus and proximal tarsometatarsus. • Other Vitamin Deficiencies Deficiencies of pantothenic acid. There are no macroscopic lesions associated with thiamine deficiency. Breeding flocks fed diets deficient in riboflavin show low egg production and hatchability. niacin. In 61 . These avitaminoses are seldom diagnosed as single entities in commercial poultry in tropical countries but contribute to a general pattern of poor growth and depressed reproductive efficiency in mature flocks. In laying hens and breeders. amprolium. hatchability is lowered and embryonic malformations of the feet are noted. The principal sign comprises dermatitis of the feet and of the skin adjacent to the angle of the beak. and analyses of representative feed samples.
Young chicks will show tail picking and cannibalism. Standard operating procedures consistent with industry practice should be developed and a quality control program implemented based on laboratory analysis and a review of production records. • improved market share and profitability. • Sodium and or Chloride Deficiency Failure to add supplementary salt to poultry diets composed of maize and soybean meal will result in depressed growth rate and decreased egg production. 7. • improving client and in-company acceptance of feeds. 62 . normal values.extreme cases displacement of the gastrocnemius tendon occurs as perosis ("slipped tendon"). • Zinc Deficiency Deletion of zinc from the mineral premix will result in decreased growth rate and chondrodystrophy. The quality of soybean meal incorporated into poultry diets is an important contributor to performance of broilers and mature stock. storage of soybean meal and formulation is available from an ASA International Office. Routine assays should include: • moisture • crude protein • fat • urease activity • protein solubility in 0. The direct and indirect benefits of comprehensive quality control invariably outweigh the capital and operating costs involved.02% potassium hydroxide Information on analytical procedures. A commitment to the principle of total quality management generates the following benefits: • enhanced performance of flocks by obviating toxicity and deficiency in diets.3 Quality Control in Feed Manufacture It is necessary to implement a comprehensive quality control program to monitor the nutritional value and composition of ingredients and to ensure thorough mixing and correct identification of diets.
Purulent conjunctivitis due to Avitaminosis A. 63 . 41. Quality control is an important component of feed production and requires trained technicians and suitable equipment.40.
Chicks affected with rickets show lowered skeletal density. 44. In this case. decreased mineralization of the mandible and maxilla allows extensive lateral movement of the beak. Avitaminosis A characterized by nodular lesions in the mucosa of the esophagus. 43. 64 . The long bones of chicks with rickets can be bent without fracture.42.
Horizontal orientation increases surface area and oxidation. Installation of a large capacity black-painted metal storage tank for feedgrade blended oil in a tropical area will lead to rancidity with consequential destruction of fat-soluble vitamins. 46. 47. Hemorrhage within the cerebellum characteristic of nutritional encephalomalacia due to a deficiency of Vitamin E or destruction of this nutrient by free radicals in oil undergoing rancidity. 65 .45. Broiler chicks aged approximately 14 days showing lateral recumbency associated with nutritional encephalomalacia.
Hemorrhage and transudate beneath the wing associated with transudative diathesis due to destruction of Vitamin E following oxidative rancidity. 50. Chicks showing edema of the intermandibular region due to transudative diathesis. 66 .48. 49. Subcutaneous hemorrhage beneath the wing of a cagehoused pullet due to Vitamin K deficiency.
Hyperkeratosis (thickening of the skin) of the plantar surface of the feet associated with pantothenic acid or biotin deficiency. 53.51. Measures to reduce heat stress are required to minimize losses. 67 . 52. Hen showing sternal recumbency due to osteomalacia. Fatty liver syndrome in a mature hen results in rupture and hemorrhage into the body cavity. This condition can be prevented by lowering the energy value of the feed and ensuring that sulphurcontaining amino acids and choline are at an appropriate dietary inclusion rate.
The characteristic MD lesion comprises enlargement of the peripheral nerves of the sciatic or brachial plexus.1 MAREK'S DISEASE Etiology An oncogenic (tumor-inducing) herpesvirus Occurrence and Economic Significance Marek's disease affects commercial chicken flocks from approximately 5 to 35 weeks of age in all areas of the world.2 8. 8. Canada. Infected birds shed "dander" (feather dust) contaminated with virus which can be distributed by wind. non-immunized flocks up to 60 weeks of age. Marek's disease virus is responsible for neural and visceral tumors.8. proventriculus. Marek's disease virus is immunosuppressive and infected broiler and pullet replacement flocks are susceptible to a wide range of viral and bacterial infections.4 8. and Europe. Highly pathogenic (vvMD) strains of the virus are responsible for acute outbreaks of mortality which may attain 50% in exposed.3 Transmission Exposure to MDV occurs by horizontal infection.6 Diagnosis and Confirmation The gross appearance of neural lesions is generally diagnostic. ovary or other organs may be affected. Clinical Signs Involvement of the peripheral nerves results in paresis (weakness) of the legs or wings which progresses to paralysis. erosive losses of up to 20% occur in non-protected or inadequately vaccinated flocks.5 8. Histological examination of nerve and visceral lesions will show characteristic 69 . Occasionally visceral lesions are observed and the kidney. Exposed broilers show increased mortality and condemnation rates at processing. equipment. and personnel. Death occurs in both caged and floor-housed birds as a result of dehydration and persecution. Pathology Enlargement of the feather follicles is observed on the skin of de-feathered broilers and results in condemnation of carcasses in the USA. eye. 8.0 8. Generally. The virus is resistant to environmental exposure and can remain viable for long periods in houses especially if units are not decontaminated between cycles.
g. frozen vaccines require special storage in a liquid nitrogen canister. 8.g. Cell-associated. It is essential to place day old chicks in houses which have been thoroughly decontaminated to allow vaccinated flocks to develop immunity. SB1) Type 3: apathogenic turkey. The causal virus may be isolated and identified by submitting tissues to a suitably equipped laboratory using specific tissue culture techniques. an emerging condition of unknown etiology.g. Three types of vaccine are available: Type 1: attenuated chicken strain (e. parents should be vaccinated with Rispen's strain. Careful reconstitution using the diluents supplied by the vaccine manufacturer is necessary to maintain viability of the vaccine virus. strain (e.7 Prevention Vaccination of broiler embryos using in ovo administration on the 18th day of incubation or by subcutaneous administration of vaccine to broiler. Rispen's) Type 2: apathogenic chicken strain (e. Improper vaccination technique may lead to defective immunization with resulting "breaks". In countries where highly pathogenic MDV occurs. breeder or replacement egg-strain chicks at day old. but suspected to be an autoimmune response to vaccination in specific strains of commercial laying hens. The condition should be differentiated from botulism and from "transient paralysis". 70 . allowing commercial progeny to be immunized using the less expensive HVT strain alone or in combination with the potentiating SB1 strain. HVT) Due to the interfering effect of maternal antibody on HVT it is advisable to alternate vaccine types in successive generations.lymphocytic proliferation. Rearing farms and broiler growing units should be operated as single-age units with all-in-all-out cycles.
(Courtesy AAAP) 71 . (Courtesy AAAP) 55. Unilateral enlargement of nerves of the sciatic plexus is characteristic of Marek's disease. Characteristic posture of an immature chicken in sternal recumbency with Marek's disease showing alternating extension and retraction of legs.54.
The vvIBD strains occur frequently in the Middle East. Contaminated equipment. 9. Very virulent (vvIBD) virus may kill up to 50% of susceptible flocks. housing. Indirect infection with IBDV occurs within days of placing chicks as the agent can survive in a contaminated environment for up to 3 months. Turkey strains are apathogenic to chickens. Infectious Bursal Disease is a major restraint to productivity and profitability in the poultry industries of both industrialized and developing nations. The variants are more immunosuppressive than the classic strains. Affected birds are depressed and show recumbency.2 Occurrence and Economic Significance The disease affects immature chickens world wide. and clothing of personnel are frequently sources of infection. Pathogenic Delaware variants A through E predominate in the USA and Central America.1 Type 2: 9.3 Transmission Direct contact of young birds with infected flocks in multi-age units results in persistent "rolling" infection which is difficult to control. Acute infection with classic mild or variant strains results in up to 5% mortality. Avibirnaviruses are immunosuppressive and predispose flocks to intercurrent viral pathogens and secondary bacterial infection. Asia and Africa.0 INFECTIOUS BURSAL DISEASE synonyms IBD:Gumboro Disease Etiology Type 1 avibirnavirus strains Type 1: Both classic and highly pathogenic (vvIBD) serotypes are recognized.9. depending upon the pathogenicity of the IBDV strain and the susceptibility of the flock. 9.4 . ruffled plumage and white diarrhea. non-pelleted feed containing inadequately heattreated poultry by-product meal. 72 9. There are no characteristic signs specific to IBD. Clinical Signs Flocks are affected acutely and show variable morbidity (5-50%) and rapidly ascending mortality (5-50%).
IBDV can be isolated in specific pathogen free embryonated eggs or on tissue culture. coli septicemia are frequent complications following exposure to respiratory viruses especially with superimposed climatic or environmental stress. A combination of live IBD virus with corresponding antibody (Bursaplex®) is available to be administered either in ovo or at day-old by the subcutaneous route. Subsequent administration of intermediate strain vaccine may be necessary depending on factors including: • Risk of infection. This program will promote transfer of high and uniform levels of antibodies to progeny. Broiler and replacement layer chicks should be vaccinated with live-attenuated vaccine which primes the immune system.7 Prevention Parent flocks should be immunized with one or more attenuated live (mild or intermediate) vaccines followed by an oil-emulsion booster. mild strain vaccines may be administered from dayold to 14 days. This is required if chicks are exposed to IBDV at the time of placement. Airsacculitis and E. In North America a mild live multivalent (classic and variant) vaccine is administered by the in ovo route to provide initial stimulation of the immune system. Histological examination of bursas from broilers or pullets at various stages of the disease will show edema progressing to atrophy. 73 . In areas of the world where relatively avirulent strains of IBD virus occur. • Intercurrent exposure to respiratory viral infections. Antibody response in vaccinated flocks should be routinely monitored using ELISA serology. can identify specific IBDV isolates. Serotyping carried out in reference laboratories using monoclonal antibodies. This vaccine is effective in the presence of high levels of maternal antibody.9. In acute cases the characteristic lesion comprises enlargement of the bursa of Fabricius which is often surrounded by gelatinous exudate. Sectioning the organ may show hemorrhages. • Strains of virus prevalent in the area of operation.5 Pathology Dehydration and muscular hemorrhages are evident in dead birds. Diagnosis Acute bursal changes are generally diagnostic. Recovered birds show bursal atrophy. 9.6 9.
D. 56.36 is the square root of 500 ELISA units. In areas of the world where the very virulent (vvIBD) strain occurs. (the threshold of protection) and 2. This formula relates the initial antibody level to the rate of decline in maternal antibody to obtain the optimal age for vaccination. Selection of the age of vaccination is determined by applying the following formula based on the results of ELISA serology at day old.82 (+1) days where 22. It is necessary to maintain strict levels of biosecurity and to operate flocks on an all-in-all-out basis in areas where severe infectious bursal disease is endemic. Age of vaccination: ELISA titre . AAAP Slide Set) 74 . (Courtesy of Dr.22. intermediate-plus ("hot") vaccines are administered in drinking water.36 / 2. Lukert.82 is the mean half life (in days) of maternal antibody.The age of administration of live attenuated vaccines depends on the level of maternal antibody and the risk of infection. P. Acute infectious bursal disease showing chicken with copious white diarrhea.
59.D. Severe nephritis characterized by pallor and urate deposit may be associated with nephropathogenic strains of infectious bronchitis virus.57. Characteristic subcutaneous and intramuscular hemorrhages associated with infectious bursal disease. (Courtesy of Dr. Enlarged bursa of Fabricius typical of acute infectious bursal disease infection. Note urate accumulation on vent plumage and enlarged kidneys. Lukert. This condition should be differentiated from mycotoxicosis and anti-coagulant toxicity. infectious bursal disease or water deprivation. 75 . P. AAAP Slide Set) 58.
Affected chicks are pale and stunted. Primary CA mortality occurs during the age period 15-20 days.6 Diagnosis ELISA and VN serology can confirm infection of flocks.1 Etiology A non-enveloped icosohedral DNA-virus. 10.2 Occurrence and Economic Significance The infection is widespread in broiler and replacement parent and layingstrain pullets. with onset at 10 days. 10. Marked anemia may be observed with corresponding hematocrit values below 15%.4 Clinical Signs Morbidity is variable. 10. The virus causes stunting and increased susceptibility to secondary viral and bacterial infections including dermatitis which results in downgrading.5 Pathology Thymus and bone marrow atrophy and muscular hemorrhages are characteristic. MDV and reticuloendotheliosis virus (REV) (a retrovirus). The pathogen is synergistic with IBDV.7 Prevention Immunization of breeder flocks during the age period 12-15 weeks using an attenuated vaccine. 10. 76 . Chicken infectious anemia virus (CAV) is immunosuppressive and is responsible for mortality of up to 10% in affected broiler flocks. 10. The PCR (polymerase chain reaction) assay can identify CAV T-cell and B-cell lymphoblastoid cell line tissue cultures can be used to isolate the agent in suitably equipped laboratories. Contaminated live vaccines prepared from infected embryos are thought to have been responsible for widespread dissemination of CA infection prior to recognition of the virus.3 Transmission Both vertical and horizontal routes of infection occur under commercial conditions. following secondary bacterial infection. Gangrenous dermatitis of the extremities ("blue wing") is noted. Septicemia and gangrenous dermatitis occur in older birds.0 CHICKEN ANEMIA 10.10. Either vaccination or natural exposure will confer immunity to progeny through maternal antibody transfer. classified as a circovirus. 10.
Biosecurity procedures are required to prevent horizontal infection. Control of respiratory infections and other immunosuppressive agents is essential to reduce the impact of CA. Appropriate management procedures can reduce the effects of primary CA infection. Pale bone marrow indicating immunosuppression associated with chick anemia virus or mycotoxicosis. subcutaneous hemorrhage. 60. 61. 77 . and transudate due to chick anemia virus. Wing of 14-day old broiler showing edema.
2 Occurrence and Economic Significance Three categories of viral pathogenicity result in different clinical forms of the disease. type 1. the UK and other European countries but are widespread in Asia. 11. highly lethal disease.1 Etiology Antigenically related strains of Avian paramyxovirus.11. especially during winter and following immunosuppression.3 Transmission ND virus is highly contagious. and Latin America. Velogenic and mesogenic forms are exotic to the USA. Disruption of trade and the cost of eradication of vvND in non-endemic countries imposes a significant burden on producers and the public sector after outbreaks. The cost and consequences (respiratory stress) of vaccination are significant. The severity and financial impact depends on climatic and management stress and intercurrent exposure to pathogenic E. The lentogenic form is responsible for erosive losses in broilers including lowered gain and feed conversion efficiency and elevated mortality and condemnation. Africa. • Mesogenic virus causes acute. Infection occurs either by the inhalation of virus in aerosol form or ingestion of contaminated feed or litter. • Lentogenic virus is responsible for mild respiratory infection. coli and other viral respiratory disease and immunosuppressive agents. backyard flocks and gamefowl serve as reservoirs. depressed egg production and lowered feed conversion efficiency occur as a result of exposure to vvND.0 NEWCASTLE DISEASE 11. • Velogenic-viscerotropic virus (vvND) infection results in acute onset. • Companion birds. 11. • Wind dispersal may occur over distances of 5 km. Canada. 79 . • Direct and indirect contact with contaminated material (fomites) is associated with deficiencies in biosecurity. The lentogenic form is encountered in most poultry-producing areas including the USA. Severe losses from mortality. moderately lethal disease with nervous and respiratory signs.
Lentogenic ND may be responsible for asymptomatic drops in egg production in incompletely immunized commercial layer or breeder flocks.4 Clinical Signs Velogenic Viscerotropic Newcastle Disease This form is characterized by acute onset with up to 100% flock morbidity and rapidly ascending high mortality (20% in 2 days. Identification and characterization of the virus by a suitably equipped laboratory is the usual confirmatory procedure. 80 . 50% in 3 days. coli.6 Diagnosis Isolation. Mild to inapparent respiratory signs are noted but negligible mortality occurs in uncomplicated cases. Recovered flocks show septicemia and airsacculitis due to secondary infection with E. In susceptible commercial egg production flocks and breeders. 11. 80% in 5 days) accompanied by respiratory and nervous signs. These changes are not specific to vvND and may be observed with highly pathogenic strains of avian influenza and vvIBD. Mesogenic Variable to high morbidity is evident in an exposed flock which will show moderate mortality characterized by nervous and respiratory signs. peracute cessation of production occurs with the presence of shell-less eggs due to premature oviposition.5 Pathology Velogenic Prominent hemorrhages occur throughout the digestive tract especially in the mucosa of the proventriculus and gut-associated lymphoid tissue. 11. The virus can be detected applying PCR technology to obtain a provisional diagnosis within a working day. Lentogenic Mild conjunctivitis and tracheitis are observed. Severe tracheitis and pulmonary congestion are evident in acute cases. Lentogenic Acute onset with moderate to high morbidity. Exposure of immunized flocks results in variable decline in production.11. An acute drop in egg production occurs in susceptible mature flocks with the presence of shell-less eggs.
Retrospective serology (ELISA. by the aerosol or eye drop route. This expedient is only justified if birds have previously received one or more live attenuated lentogenic vaccines. depending on antibody titer of the flock. management system.7 Prevention Vaccination. hemagglutination inhibition and serumvirus neutralization) demonstrates the presence of antibodies which indicates exposure to ND virus and the titer (level) can differentiate between field infection and previous vaccination. 11. and other factors relating to the operation. • Subsequent vaccinations include 24 day. • In areas with a defective cold-chain the V-strain live thermostable mutant ND can be distributed to subsistence and backyard flocks. incorporating day-old subcutaneous emulsion vaccine together with attenuated live vaccine by the eye-drop route. In countries with endemic vvND. • Lentogenic infection of breeders can be prevented by 10 day administration of Hitchner B1. Breeders may be immunized with mesogenic-strain vaccines in some countries. A variety of vaccination programs can be followed depending on the risk of infection. An optional 45 week multivalent oil inactivated emulsion may be administered to boost maternal antibody transfer. Hitchner or LaSota vaccine is administered to broilers by the aerosol route at 10 day intervals thereafter. and 8 week Hitchner B1 or LaSota in non-chlorinated drinking water. rigorous programs are implemented. 81 . virulence of agent. • Recombinant pox and HVT-vector vaccines expressing the fusion (F) protein of NDV are available for either in ovo or subcutaneous vaccination. Conventional programs: • Lentogenic infection of broilers can be prevented by day old administration of aerosol or eye drop vaccine using Hitchner B1 with subsequent boosters in drinking water or by the aerosol route. and economic factors. followed by multivalent oil inactivated emulsion at 18-20 weeks. risk of exposure. • Administration of a preparation comprising live virus with complementary antibody (Newplex®) by the in ovo route at 18-days of incubation is protective in countries where the vaccine is available.
Broiler flock showing high morbidity and mortality due to velogenic Newcastle disease or HPAI. 82 .62. Torticollis in an immature chicken infected with velogenic Newcastle disease. The trachea yields virus for PCR analysis and for isolation and identification of viral and bacterial pathogens of the respiratory tract. 63. (Courtesy University of Pennsylvania) 64.
or mild avian influenza.65. Hemorrhage of the mucosa of the proventriculitis due to velogenic Newcastle disease. (Courtesy of the University of Georgia). Acute onset of ocular discharge accompanied by high flock morbidity may denote infectious laryngotracheitis. infectious bronchitis. 66. coryza. 83 .
12.3 Transmission Direct contact with clinically affected chickens or recovered permanent carriers.5 Pathology Hyperemia of the tracheal mucosa is present in most cases. The fluorescent antibody technique may be used to demonstrate LT antigen in respiratory mucosa. 12.12. Decreased egg production occurs following exposure of mature susceptible flocks. Wind dispersal over 3 km has been documented. or contaminated personnel or equipment.6 Diagnosis Histopathology usually reveals the presence of intranuclear inclusion bodies in the epithelium (cell lining) of the trachea. immune status of the flock and environmental conditions.4 Clinical Signs The severity of LT is influenced by the strain of virus. Aggregations of desquamated epithelium and blood clots may obstruct the glottis resulting in asphyxiation.0 INFECTIOUS LARYNGOTRACHEITIS Synonyms LT & ILT 12. 12. Indirect contact through dust-laden vehicles. In severe cases. Proportionally more severe lesions occur with pathogenic virus strains which produce severe hemorrhagic tracheitis with the presence of blood clots.1 Etiology Gallid herpesvirus 1. Moderate to severe strains of LT result in proportionately higher morbidity and mortality in both mature and rearing stock with losses approaching 50% with concurrent environmental stress and other infections. 12. conjunctivitis and swollen heads. birds show expectoration of blood accompanied by cyanosis of the head due to dyspnoea.2 Occurrence and Economic Significance Laryngotracheitis is distributed worldwide but is frequently regional in prevalence or seasonal in incidence. Mild to severe cases show acute onset with respiratory signs (snicking and gurgling). Mild LT results in lowered growth rate and feed conversion efficiency and elevated mortality and condemnation in broilers. The LT virus can be isolated using SPF embryos or tissue culture with identification applying immunofluorescence or serum-virus 84 . 12.
immature breeders and commercial pullets at 14 . It is impossible to differentiate among the causes of respiratory diseases based on clinical observation only. (Courtesy of the University of Georgia) 85 . Detailed laboratory evaluation with identification of pathogens is required to confirm a diagnosis.7 Prevention Strict biosecurity measures are justified in endemic areas. 12. Commercial egg pullets and breeders are vaccinated at 6-10 weeks of age by administration of tissue-culture origin modified live virus which has a lower potential for reversion to virulence than chick-embryo origin vaccine virus. LT may be transmitted to susceptible flocks or to unaffected areas following movement of vaccinates. Effective protection can be achieved using egg-embryo propagated vaccine administered in drinking water to broilers. Since flocks immunized with chick embryo origin virus serve as permanent carriers of the vaccine virus.20 days. 67.neutralization. New vaccine candidates based on recombinant DNA technology should overcome the problem of reversion associated with live modified vaccines. Broiler with swollen face and dyspnea due to laryngotracheitis. ELISA serology may be used to confirm infection by demonstrating a significant rise in antibody in paired serum samples obtained during the acute and recovery phases of infection. The spray route is less effective especially with tissue-culture propagated vaccines.
70. Specific laboratory procedures are required to establish a diagnosis. avian influenza Newcastle disease or adenovirus. Severe hemorrhagic tracheitis characteristic of infectious laryngotracheitis.68. (Courtesy of Dr. Caseous cast in the proximal trachea adjacent to the glottis is characteristic of laryngotracheitis but should be differentiated from diphtheritic pox infection and avian influenza. Tripathy. D. AAAP slide set) 69. Tracheitis which may be due to a range of viral agents including laryngotracheitis. 86 . N. infectious bronchitis.
Direct infection occurs following contact between infected carriers and susceptible flocks. Avian influenza viruses vary in their pathogenicity and their effects range from a mild respiratory disease (LPAI) to catastrophic losses associated with viscerotropic and pansystemic infection (HPAI or "fowl plague").13.2 Occurrence and Economic Significance Avian influenza is world-wide in distribution. Rapid multiplication of HPAI virus occurs in susceptible subsistence and commercial flocks.1 Etiology Diverse Type-A orthomyxoviruses characterized by hemagglutinating (HA) and neuraminidase (N) antigens occurring on the surface of the virus. Influenza adversely affects the financial return from flocks and a decline in quality of broiler carcasses or table-eggs following infection. This situation is common in countries with extensive distribution of live birds and where multi-age flocks are operated. disruption in operations and high costs for control and prevention. 13. The virus is relatively resistant to environmental exposure and can infect birds placed in imperfectly decontaminated units housing a previously infected flock. 13. Avian influenza of low pathogenicity is an erosive disease reducing liveability and quality of either broilers or eggs and exacerbating secondary bacterial infection. Sporadic outbreaks of HPAI result in severe losses in production. equipment and personnel and by wind dispersal of virus-laden dust and feathers. Indirect infection can occur by moving flocks. 87 . Flock morbidity is apparent following exposure to AI virus but mortality is variable depending on the pathogenicity of the strain of AIV and intercurrent climatic and environmental conditions. ultimately affecting all poultry operations in a region. 13.4 Clinical Signs Highly pathogenic avian influenza (HPAI) results in an acute and precipitous decline in egg production with rapidly ascending mortality characterized by both respiratory and nervous signs.0 AVIAN INFLUENZA 13.3 Transmission Wild birds serve as reservoirs and transmit infection to subsistence flocks or commercial units which are operated with substandard biosecurity. unless appropriate controls are implemented.
impeding exports. ILT.7 Control in Areas Where Exotic HPAI is Diagnosed Exotic outbreaks of HPAI are eradicated by implementing an intensive program comprising rapid diagnosis. coli infection superimposed on flocks with a history of exposure to immunosuppressive infections (IBD. Vaccination suppresses clinical occurrence of disease but the virus persists in the poultry population of the affected region. 13. and a decline in egg production. CA) and with concurrent respiratory pathogens (MG/ MS. 13.5 Pathology Highly pathogenic avian influenza is characterized by subcutaneous hemorrhages and edema of the head. Elevated mortality follows secondary E. An alternative but more time-consuming approach involves isolation of a hemagglutinating virus from tissues using specific pathogen free embryos or avian-cell tissue culture systems. Restriction on movement of flocks and products from foci of infection should be imposed.Mild strains (LPAI) result in low morbidity and mortality. slaughter and disposal of affected flocks. 13. quarantine and concurrent surveillance with subsequent disposal of flocks demonstrating antibodies to AI. Studies in industrialized nations have shown that strict biosecurity can limit dissemination of avian influenza virus among commercial farms 88 . pulmonary edema and if secondary bacterial infection occurs. AI viruses are then identified and serotyped using serumvirus neutralization followed by more advanced sero-immunologic procedures conducted in suitably equipped laboratories. Mild influenza results in tracheitis. ND. The agar-gel immuno-diffusion test and the ELISA procedure are used to demonstrate group specific AI antibody in serum. IB).6 Diagnosis Rapid presumptive diagnosis is based on solid-state antigen capture assay (Directigen®) and confirmed by RT-PCR assay. denoting either exposure or vaccination. Vesicles may be present on the comb and wattles. flocks are immunized using autogenous inactivated vaccine or a recombinant vector product. airsacculitis is observed. In areas where inadequate resources or extensive dissemination of infection precludes absolute eradication. Hemorrhages are observed in the serosa of all viscera and in the mucosa and lymphoid structures of the intestinal and respiratory tracts.
and within integrations. Preventing the spread of virus is extremely difficult in the context of industries in developing countries where feed is delivered in bags, and eggs, culled hens and live broilers produced by small-scale farmers are distributed through a network of dealers to regional markets. Since 1997, the zootiotic potential of AI has been recognized. Human fatalities associated with the 2004 outbreak of the H5N1 strain of AI in Southeast Asia has created international pressure for extensive vaccination to suppress infection in regions and nations where HPAI has resisted traditional eradication programs and has become endemic. 13.8 Recent Outbreaks of H5N1 Avian Influenza in Asia The 2003/2004 outbreak of H5N1 strain highly pathogenic avian influenza probably had its origins in China. Migratory waterfowl are considered to have introduced LPAI infection into free-living resident birds including sparrows and crows in the vicinity of feed mills and farms. These birds in turn transmitted virus to domestic subsistence chickens maintained under extensive management. Wild waterfowl may have also directly infected free-roaming domestic ducks and geese. Extensive movement of live domestic poultry to markets disseminated infection which eventually was introduced into large commercial operations. The H5N1 virus underwent mutation in large susceptible populations, resulting in a highly pathogenic agent. Spread of infection from China to Vietnam, Cambodia, Laos and Thailand was associated with unrestricted cross-border movement of live poultry including fighting cocks. Failure to recognize the infection and to implement appropriate control measures including quarantines, depletion of affected and contact flocks and vaccination has resulted in the development of endemic HPAI status in most countries in Asia where the disease has emerged. In Japan, Taiwan, Malaysia and Korea, limited outbreaks of H5N1 infection have been eradicated applying appropriate control measures for regions where the disease is exotic. China and Indonesia have adopted vaccination to suppress clinical outbreaks, recognizing this strategy to be the most cost-effective control measure. Asian outbreaks of H5N1 AI have been characterized by limited infection of humans following direct contact with diseased poultry. As of mid-2004 there have been no reports of direct human-to-human contact transmission. It is possible that a recombinant event between avian H5N1 and human influenza strains could occur in domestic swine or other animal species
yet to be identified in the chain of transmission. This could potentially result in a more pathogenic virus affecting humans, justifying vigorous suppression of infection in poultry populations and absolute separation of swine and poultry. Alternative strategies to control HPAI in countries with endemic infection should comprise detection and surveillance followed by depletion of infected flocks with fair compensation, quarantines and intensive vaccination appropriate to the circumstances. In the event of extensive spread of HPAI in a region, administration of a HA-homologous inactivated vaccine will reduce the proportion of susceptible birds in a population. This will inhibit the multiplication and dissemination of HPAI infection. The extent and severity of H5N1 infection in Asia presumes persistence of virus in reservoir populations, requiring a commitment to long-term vaccination and intensified biosecurity for commercial farms.
Subcutaneous hemorrhage characteristic of H5N2 strain of highly pathogenic avian influenza. (Courtesy of the University of Pennsylvania).
Cyanosis of the head observed in cases of H5N2 strain highly pathogenic avian influenza. (Courtesy of the University of Pennsylvania).
Severe hemorrhagic enteritis characteristic of highly pathogenic avian influenza or velogenic Newcastle disease. (Courtesy of the University of Pennsylvania).
Vesicle formation on the wattle of a bird infected with highly pathogenic influenza virus.
Visceral hemorrhages associated with velogenic viscerotropic Newcastle disease. Similar lesions are observed with highly pathogenic avian influenza. (Courtesy University of Pennsylvania)
7 Prevention Immature breeders and commercial layer flocks are routinely vaccinated with a mild attenuated product (H-120.4 Clinical Signs Moderate morbidity and low flock mortality associated with respiratory rales (gurgling and snicking) and ocular discharge.14. Mature flocks show reduced egg production with malformed shells. 14. 14. The vaccination is repeated at 30-40 days. climatic stress or intercurrent mycoplasmosis. 14.5 Pathology Hyperemia (red discoloration) of the trachea and accumulation of mucus in the nasal cavity. coli infection show airsacculitis. Infection of immature chickens causes a mild respiratory disease which may affect liveability and growth if exacerbated by adverse managemental. 14. Massachusetts. Where suitably equipped laboratory resources are available. complicated by secondary E. 14.0 INFECTIOUS BRONCHITIS 14.2 Occurrence and Economic Significance Infectious bronchitis (IB) occurs world wide and is responsible for depressed egg production and shell quality in susceptible commercial and breeder flocks.6 Diagnosis The diagnosis can be confirmed by immunofluorescence assay or isolation and identification of the causal virus using egg inoculation or tissue culture techniques. 14. RT-PCR is used to rapidly diagnose IB.3 Transmission The virus can be transmitted from clinically affected birds to susceptible flocks either by direct contact or indirectly by fomites. Connecticut strains or their combination) at 7 days in drinking water or by aerosol. Chronic cases.1 Etiology Specific strains of an avian coronavirus. Retrospective diagnosis is possible by demonstrating a significant rise in circulating antibody in paired acute and recovery-phase sera applying ELISA or SN assay. The initial live vaccine should always be administered to susceptible breeder and layer flocks before 12 weeks of age to avoid possible damage to the developing reproductive tract of 93 .
as considered necessary. usually in the form of an injectable multivalent emulsion at the end of the rearing period and then at mid-cycle.the pullet. 94 . Potential breeder flocks receive inactivated IB vaccine as a booster. Broilers in endemic areas are vaccinated by aerosol at day-old or subsequently by coarse spray or in drinking water at a suitable time (1020 days) depending on maternal antibody transfer or pattern of field challenge. In many areas specific IB vaccines are required to prevent clinical problems attributed to variant strains. to maintain adequate maternal antibody transfer to progeny. Immunity in commercial layers can be boosted by administration of live attenuated vaccine either in drinking water or as a coarse spray during the production period.
95 . synoviae infection. and condemnation at processing. In commercial layers and breeders. Mycoplasmas do not survive outside the host for longer than 24 hours.3 Transmission Mycoplasmosis is transmitted by the vertical route from infected parent flocks to progeny. 15. feed bags.15. 15. Chronic cases are emaciated and show purulent nasal discharge. elevated mortality. 1 Etiology Mycoplasma gallisepticum and M. synoviae are the two significant species affecting commercial chickens. These conditions are responsible for extensive losses in broiler operations especially where flocks are exposed to concurrent viral respiratory diseases and environmental stress.0 MYCOPLASMOSIS 15. gallisepticum and synovitis and airsacculitis due to M. Lateral transmission occurs by direct contact between clinically affected or recovered carriers and susceptible flocks. Wild birds and rodents may transmit the disease to susceptible flocks. The economic impact of mycoplasmosis in broilers includes severely depressed growth rate and feed conversion efficiency. markedly reduced growth rate and an increased susceptibility to intercurrent respiratory diseases.4 Clinical Signs Mycoplasmosis is characterized by chronic respiratory signs including ocular discharge. 15. tracheal rales ("gurgling and snicking"). occur world-wide. M. liveability and egg production are depressed. synoviae infection results in acute arthritis especially of the hock and stifle joints.2 Occurrence and Economic Significance Chronic respiratory disease caused by M. Indirect infection occurs through contact with contaminated equipment. and personnel.
In advanced cases. This procedure may require up to 30 days and may be inconclusive due to technical problems including contamination. 15. sensitive and specific test procedure. The liveattenuated F-strain vaccine administered in drinking water has been largely replaced in the USA by the milder TS-11 and 6/84 products. The hemagglutination inhibition test is applied to confirm the provisional serologic diagnosis. These highly sensitive tests are used to screen flocks. Acute cases of M.15. gallisepticum vaccines are available for immature egg-production flocks which will be transferred to multi-age. gallisepticum and/or M. Mycoplasma spp can be isolated and identified by inoculating tracheal swabs or serous joint exudate from acute cases onto special selective media.8 Prevention The world's primary breeders of broilers and commercial layers have eliminated mycoplasmosis.6 Diagnosis Two to three weeks following infection. Infection of grandparent and parent level breeders occurs in developing industries due to deficiencies in biosecurity on farms operated by multipliers. synoviae infection show serous arthritis. The polymerase chain reaction assay can be applied as a commercially available. Kits are available for M. It is essential to purchase parent and commercial stock from known mycoplasma-free breeder flocks.5 Pathology Affected birds show congestion of the upper respiratory tract. synoviae respectively. Live M. Chicks derived from known infected parent flocks can be treated with a suitable antibiotic during the first 48 hours after placement and re-treated subsequently at 20 to 24 days of age for a 24 to 48 hour period. infected layer farms. Inactivated vaccines administered as oil emulsions are available commercially but 96 . chickens demonstrate antibodies which can be detected using the serum plate agglutination test or the automated ELISA technique. Strict biosecurity will prevent lateral introduction of infection. seropurulent exudate may be present in affected joints. and in chronic cases airsacculitis and colibacillosis. 15.7 Treatment Clinical signs can be suppressed by administering tylosin or a fluoroquinolone compound in drinking water. It is emphasized that treatment does not eliminate the carrier state in infected flocks but will suppress excretion of the organism in respiratory exudate and vertical transmission through eggs. mild tracheitis. 15.
are of limited value. It is noted that vaccination will suppress clinical signs of infection but will not eliminate the carrier state. A pox-vectored recombinant Mg vaccine ("Vectormune") has recently been licenced for administration to immature egg-production pullets in the USA. 97 .
Acute foamy airsacculitis due to Mycoplasma gallisepticum infection.76. Caseous airsacculitis associated with Mycoplasma gallisepticum infection. Positive Mycoplasma gallisepticum Serum Plate Agglutination Test on right contrasted with negative test on left. 98 . 78. 77.
16.3 Transmission Infection follows direct contact with clinically affected or asymptomatic carriers or indirect contact with contaminated equipment or personnel. Chronic cases show serous to caseous sinusitis. and other respiratory agents. B and C are recognized. 16. 16. Alternatively.7 Treatment Immature birds can be treated with water-soluble sulfonamides. Since the organism is susceptible to desiccation it is recommended that acutely infected live birds should be submitted to a diagnostic laboratory whenever possible. 16.5 Pathology Acute cases show severe conjunctivitis and inflammation of the periorbital fascia. Mortality is negligible in uncomplicated cases of coryza.1 Etiology Three Haemophilus paragallinarum serotypes designated A.2 Occurrence The disease is potentially encountered in any poultry-raising area but frequently occurs in specific regions or countries as a chronic or seasonal problem. incubated in a candle jar. 16. Coryza results in decreased egg production in commercial multiage laying and breeder operations. severed heads packed on ice can be forwarded to a laboratory. These 99 . Egg production in young commercial or breeder flocks is reduced following infection. 16.6 Diagnosis Haemophilus paragallinarum can be isolated from sinus swabs in acutely affected birds. The condition should be differentiated from pasteurellosis and viral infections including LPAI. The pathogen does not remain viable outside the host for periods exceeding 24 hours. Clinically affected birds show unilateral or bilateral ocular discharge progressing to facial cellulitis and chronic sinusitis.4 Clinical Signs Flock morbidity varies from 1 to 20%. Isolation involves semiaerobic culture on a blood agar medium streaked with Staphylococcus sp.0 CORYZA 16. 16.
Combinations of tetracyclines are frequently used to treat coryza by administration in water or injected directly by the intramuscular route. Ocular discharge and swelling of the nasal sinus associated with Coryza. Immature flocks can be partly protected by administration of inactivated multivalent or homologous bacterins in aqueous suspension or oil emulsion.8 Prevention Appropriate biosecurity measures will limit the possibility of introducing infection on to breeding and commercial egg production farms. 79. Compulsory or recommended withdrawal periods before marketing eggs should be followed after treatment of commercial flocks. Differential diagnosis includes mycoplasmosis or laryngotracheitis.drugs should not be administered to mature flocks due to residues in eggs and the deleterious effect of sulfonamides on production and shell quality. 100 . as recommended by the manufacturer. 16. Accumulation of purulent material in the infraorbital sinus is characteristic of coryza. 80. Two doses of inactivated vaccine should be administered by the subcutaneous or intramuscular route at four week intervals during the rearing period.
frequently accompanied by a whistling rale. Histological examination of lungs will reveal characteristic hyphae.0 ASPERGILLOSIS synonym Mycotic Pneumonia 17.17. Chicks older than 48 hours are usually refractory to infection by inhalation of spores.7 Prevention Improving nest-box hygiene. Horizontal transmission can occur in the hatchery or during handling and delivery.4 Clinical Signs Morbidity may attain 10% of the flock with corresponding mortality during the first 3–12 days. Mycotic encephalitis (infection of the brain) results in lateral recumbency. 17. 17.5 Pathology Numerous 1mm diameter yellow to green nodules are observed in the lungs and air sacs and occasionally in other organs including the brain and eye. 17. Decreased growth rate and ascites complex are noted in affected survivors.6 Diagnosis Characteristic lesions are highly suggestive of aspergillosis. This is followed by subsequent infection of the respiratory tract of pipping embryos and hatching chicks. increasing the frequency of collection of 101 .2 Occurrence and Economic Significance The disease is world-wide in distribution but cases are more frequently diagnosed in tropical countries especially during warm and humid weather.3 Transmission Contamination of egg shells with Aspergillus spores results in colonization of the air cell. 17. Severe outbreaks associated with hatchery contamination may result in up to 15% chick mortality during the first two weeks.1 Etiology Various fungi including Aspergillus fumigatus. 17. Affected chicks are disinclined to move and show labored breathing with extension of the head. Confirmation of the diagnosis requires culture using an appropriate fungal medium (Sabouraud's dextrose agar). incoordination and coarse muscle tremors. 17.
but eggs should not be washed by immersion. using an appropriate microbiological detection procedure such as an air sampler or exposed petri-plates. hatchers. Decontamination of eggs by formalin fumigation or application of a QAT or phenolic disinfectants is advised." The efficacy of cleaning procedures can be monitored.eggs to four times daily and where possible. substituting plastic nest pads for litter will reduce the prevalence of aspergillosis. and air ducts is recommended including the use of aerosol generators and medicated "candles. 102 . Decontamination of setters.
83. 103 . Multiple fungal granulomata typical of aspergillosis. Diffuse airsacculitis of the thoracic air sacs and focal airsacculitis and peritonitis due to aspergillosis in a young chick.81. Severe pulmonary aspergillosis showing numerous nodular foci and confluent lesions. 82.
4 Clinical Signs Under commercial conditions SHS is characterized by acute onset of morbidity involving up to 10% of the flock in broilers aged 14 .1 Etiology Swollen Head Syndrome (SAS) is a multifactorial condition involving the sequence of immune suppression (IBD. Outbreaks of facial cellulitis in chickens have been diagnosed in California without evidence of metapneumovirus infection. coli cellulitis of the subcutaneous tissues surrounding the eyes and of the head. Affected birds show ocular discharge and conjunctivitis progressing to periorbital swelling. especially in high-density broiler growing areas.2 Occurrence and Economic Significance The condition occurs in southern Africa. or high dust and ammonia levels) due to inadequate ventilation or climatic extremes exacerbate the prevalence and severity of SHS. coli or other opportunistic pathogens including Ornithobacterium rhinotracheale (ORT) can be introduced through contaminated water and litter. 18. SHS often shows a seasonal (winter) occurrence. Regionally. Subsequent bacterial septicemia and airsacculitis which occur approximately 10 .3 Transmission The immune suppressive and respiratory agents are transmitted by direct and indirect contact and usually are associated with defects in biosecurity. Pathogenic E. ND) and terminating in E. CA) followed by exposure to a respiratory virus (IB. Related metapneumoviruses including turkey rhinotracheitis virus (TRT) causing tracheitis and sinusitis in turkeys and a swollen head condition in broiler breeders are accepted as a precipitating agent of SHS in broilers. coli strains. usually introduced through contaminated drinking water are responsible for the subcutaneous facial and occipital cellulitis which is characteristic of SHS.0 SWOLLEN HEAD SYNDROME 18. eyes are closed and enlargement of the head is a prominent sign in severely depressed or recumbent broilers. Pathogenic E. 105 . 18.18. Asia. TRT. 18. Terminally. the Middle East.30 days. and Latin America. MD. Losses due to primary mortality may attain 10% to 20% of the flock. especially on multiple-age farms. Environmental stress (low temperature and humidity.14 days after the onset of acute facial cellulitis may result in additional flock mortality of up to 20% of survivors of an acute outbreak.
5 Pathology Subcutaneous accumulation of viscous sero-purulent exudate. Attempts to isolate and identify primary viral pathogens and secondary bacterial pathogens should be carried out. Appropriate vaccination programs are required to prevent immunosuppressive and respiratory viral diseases. Acutely affected birds may show tracheal hyperaemia and pulmonary congestion. Differential diagnoses include LPAI. may be apparent. 18. Improper or prolonged use of antibiotics will result in emergence of drug-resistant E.7 Treatment Administration of water soluble antibiotics including fluoroquinolones will produce a transitory decline in flock mortality. IB. 18.8 Prevention Chlorination of drinking water to 2 ppm and installation of closed (nipple) drinking systems are recommended. 18.18. Serologic profiling of flocks is necessary to determine the pattern of maternal IBD antibody decay and the response to either vaccination or field challenge with a range of respiratory and immunosuppressive agents. Medication should be guided by anticipation of a positive benefit:cost ratio. coryza. 106 . Bursal and thymic atrophy consistent with previous IBD or CAV infection. coli. Antibiotics should be used in accordance with the manufacturer's instructions and statutory restrictions relating to the withholding period before slaughter should be observed. Chronic cases show caseous airsacculitis. Alleviation of obvious managemental deficiencies and environmental stress factors will reduce the intensity of respiratory stress. which becomes caseous in chronic cases.6 Diagnosis The obvious gross lesion comprising subcutaneous cellulitis of the head is highly suggestive of SHS. Losses frequently resume after withdrawal of medication. pasteurellosis. perihepatitis and peritonitis. ND. In small-scale operations acute cases can be salvaged by transfer to small pens where food and water are available and birds can be treated with parenteral antibiotic and protected from persecution by the remainder of the flock. respectively.
ND. Swollen Head Syndrome in broiler showing cellulitis of the face and head with symblepharon (closed eyes). IB by vaccination and improved flock management and provision of chlorinated drinking water will reduce losses. S. (Courtesy of Dr.Breeders can be vaccinated with commercial metapneumovirus vaccines. Control of IBD. Buys) 107 . Attempts at immunization of broilers have not been successful. 84.
Birds surviving acute airsacculitis show stunted growth and develop a caseous exudate in the air sacs often accompanied by peritonitis. 19.1 Etiology Pathogenic strains of E. coli infection. elevated flock mortality. and generalized venous congestion. 19. coli infection are responsible for decreased growth rate and feed conversion efficiency. enlargement of the spleen and liver. superimposed on primary immunosuppressive and respiratory viral infections.19. Bursal atrophy indicating previous exposure to IBDV is often observed. coli is introduced onto poultry farms through contaminated drinking water. coli airsacculitis. Total losses may attain 50% in immunosuppressed broiler flocks subjected to environmental stress and previous exposure to viral respiratory pathogens and mycoplasmosis.0 SEPTICEMIA AND AIRSACCULITIS 19. equipment and drinking systems. downgrading and condemnation of carcasses in processing plants. Flocks infected with vertically transmitted or acquired mycoplasmosis are extremely susceptible to E. Diets containing aflatoxins or free radicals evolved from peroxidation of lipids will lead to immunosuppression with increased susceptibility to E. Immunosuppressive and respiratory viruses which precipitate infection are transmitted by direct and indirect contact especially on multi-age farms or where biosecurity is defective. pericarditis and peritonitis.5 Pathology Acute septicemia is characterized by pulmonary congestion.2 Occurrence and Economic Significance Septicemia and airsacculitis resulting from E.3 Transmission E. High levels of infection occur following deficiencies in routine decontamination of housing. Infection of commercial laying and breeding stock during the rearing period may adversely affect subsequent performance. 19. 108 . resulting in downgrading or condemnation at processing. 19. Most birds which die of septicemia show perihepatitis. coli.4 Clinical Signs Flock morbidity of up to 10% occurs during the 10 – 40 day period accompanied by ascending mortality which may either plateau or decline but usually persists until depletion of the flock.
19. It is necessary to perform antibiograms to ensure that selected drugs are effective.19.7 Treatment Mortality can be suppressed by administration of water soluble furazolidone. Grossly enlarged yolk-sac of a chick showing redtinged contents associated with omphalitis.8 Prevention Refer to 18. identification and serotyping of E. coli from heart blood. 19. Evaluation of the epidemiology of immunosuppressive and respiratory infections by serology and isolation is recommended. and liver tissue. Medication should be administered in accordance with statutory restrictions concerning withdrawal and must comply with the manufacturer's recommendations. sulfonamides. 86.6 Diagnosis Isolation. and fluoroquinolones where these drugs are permitted. Hand cleaning of hatching eggs is an undesirable practice and leads to "exploders" in setters and hatchers and omphalitis in chicks due to bacterial contamination. perivisceral exudate. Swollen Head Syndrome.8. 85. 109 .
110 . 88. Chronic salpingitis occurs frequently in old breeder hens and is probably due to an ascending E. coli infection.87. Enlarged yellow yolk-sac. coli infection of the oviduct. typical of omphalitis in a 3 day old chick. 89. Pericarditis which is usually associated with E.
and clothing of personnel. 20.3 Transmission Vertical transmission occurs by the transovarial route.20.1 Etiology: Salmonella pullorum 20. housing.0 SALMONELLOSIS-PULLORUM DISEASE 20. liver) and chronic caseous typhlitis characterized by grey casts in the ceca. Horizontal transmission takes place by direct contact between clinically affected and recovered carriers and by indirect contact with contaminated equipment. BWD) is potentially world-wide in distribution but in practice is confined to non-commercial flocks in many countries. From 14 days of age onwards affected birds show stunting. intestine or yolk sac using appropriate enrichment culture and standard microbiological techniques. 20. The pathogen can remain viable in soil for up to a year. lungs. Infection results in high mortality in young chicks. internal serosa. 20. pullorum from liver.5 Pathology Chicks show enlargement of the spleen and liver. Affected chicks are depressed and anorexic and tend to huddle under brooders. Omphalitis is often present.6 Diagnosis Isolation and identification of S. 112 . poor feathering and frequently lameness due to arthritis. Chronic cases show abscessation of the viscera (heart. Recovered carriers can be identified using the rapid whole blood plate agglutination test. 20.2 Occurrence and Economic Significance Pullorum disease (or "bacillary white diarrhea". litter. Birds may show copious white diarrhea and accumulation of fecal material adherent to the plumage surrounding the vent.4 Clinical Appearance Morbidity in affected batches of chicks often exceeds 40% with corresponding mortality commencing at hatch and extending through 21 days.
20. Affected flocks should be depleted to eliminate chronic carriers. Strict biosecurity should be enforced to prevent introduction of the pathogen from backyard flocks which serve as reservoirs. 20.8 Prevention Breeding stock and chicks should be purchased from suppliers and hatcheries certified free of S.7 Treatment None is recommended. Rodent eradication is an important component of control. Breeder flocks can be monitored using the rapid whole-blood plate agglutination test. 113 . pullorum by a responsible government agency.
Diarrhea. The rapid whole blood plate agglutination test will demonstrate antibodies approximately 2 weeks after infection and can be used to screen flocks for reactors. 114 . The disease is responsible for serious economic losses in commercial units in organized poultry industries in endemic areas.6 Diagnosis Isolation and identification of S.10% within a week. which should be depleted. Peritonitis may be present in chronic cases. where permitted.2 Occurrence and Economic Significance Potentially world-wide in distribution and frequently encountered in subsistence or semi-commercial flocks. 21. Eggs should not be marketed during medication or the subsequent withdrawal period.7 Treatment Treatment is inappropriate for breeding flocks. No characteristic prodromal signs are noted. Producers in Latin America and Asia experience mortality in both mature and immature flocks. 21. 21.3 Transmission Vertical and lateral transmission occurs as for S. Oophoritis (inflammation of the ovary) followed by ovarian regression is noted in mature stock. 21.1 Etiology: Salmonella gallinarum 21.21.4 Clinical Signs Acute onset of fowl typhoid occurs in susceptible flocks which are exposed to infection. for two weeks. gallinarium is required to confirm the diagnosis. Commercial laying flocks may be salvaged under specific conditions by administering furazolidone or tetracycline in feed at 400 g/ton.5 Pathology Gross enlargement of the spleen and liver are observed in affected cases.0 SALMONELLOSIS-FOWL TYPHOID 21. Ascending morbidity and corresponding mortality may attain 5 . pullorum. loss of egg production and increased costs incurred by prevention and treatment. 21. depression and a decline in egg production are observed in mature flocks but these signs are not diagnostic.
115 . Administration of live 9R strain S. gallinarum vaccine during the rearing period will eliminate outbreaks of clinical disease. to prevent introduction of infection. Bacterins are generally ineffective in preventing fowl typhoid. pullorum infection.8 Prevention Appropriate biosecurity measures should be implemented as for S.21.
Enteritidis) and poultry meat (S. 22. Other Salmonella spp may be transmitted mechanically by fecal contamination of egg shells. typhimurium. phage type 4.2 Occurrence A world-wide problem in integrated commercial-egg and broiler operations and also on small-scale farms. Vertically transmitted S. may result in high chick mortality consistent with S. Feed containing contaminated ingredients of animal-origin is often responsible for introduction of paratyphoid salmonellosis into integrations or entire countries. S. 22. 22. enteritidis is transmitted vertically by the trans-ovarial and transoviductal routes. Pullorum infection. S. heidelberg and possibly up to 50 other frequently encountered serotypes). Paratyphoid salmonellosis can be introduced by contaminated equipment. Chicks may show omphalitis.3 Economic Significance Some Salmonella spp including S.1 Etiology Salmonella spp other than S. Generally paratyphoid Salmonella spp will result in up to 3% losses during the first 14 days. The condition can be perpetuated by recycling contaminated by-product meal from infected broilers and commercial laying flocks. gallinarum. or in cases of immunosuppressed flocks. 22. Rodents and litter beetles serve as reservoirs of infection. pullorum and S. 22. agona. personnel and wild birds. enteritidis pt 4 infection resembles pullorum disease in chicks. enteritidis. infrequently by the transovarial route.22. Paratyphoid Salmonella spp are responsible for food-borne infection in consumers of eggs (S.6 Pathology Acute cases show enlargement of the spleen and liver and occasionally enteritis and peritonitis.0 SALMONELLOSIS-PARATYPHOID 22.4 Transmission S.5 Clinical Signs Elevated chick mortality and unevenness in brooding flocks are observed. 116 . No specific signs are associated with paratyphoid infection in mature flocks.
22. or heart blood. Specific ELISA-based test kits are available for assaying for S. enteritidis emulsion boosters at point of lay.8 Treatment Furazolidone if allowed will suppress mortality but will not eliminate infection. Routine microbiological screening of liver/spleen/intestinal pools from post mortem submissions to laboratories is strongly recommended. 117 .9 Prevention Reduction in prevalence in breeding flocks is possible (absolute elimination of S. 22. modified S. typhimurium vaccines alone or in combination with inactivated S.7 Diagnosis Confirmation is based on isolation and identification of Salmonella spp from liver. Salmonella enteritidis is controlled in commercial level stock using live. typhimurium carriers) by implementing intensive programs of microbiological screening together with appropriate biosecurity procedures. enteritidis antibody. 22. spleen. Enteritidis and progressively S. intestine.
Regression of the ovary in a mature hen due to Salmonella pullorum infection. This change is not characteristic of salmonellosis but may be observed with a number of bacterial infections including E. coli and Pasteurella spp. (Courtesy of the University of Georgia) 92. Enlargement of the liver with Salmonella gallinarum (Fowl Typhoid).90. 118 . Accumulation of urate and excreta in the vicinity of the vent in chick with Salmonella pullorum infection. 91. hence the designation "Bacillary White Diarrhea" (BWD) in the British commonwealth.
Panophthalmitis in a turkey poult is characteristic of Salmonella arizona infection, but may occur with S. pullorum in chicks.
Multiple focal abcessation of the liver and heart following Salmonella gallinarum infection. These changes may also be seen with S. pullorum.
23.0 PASTEURELLOSIS synonym Fowl Cholera 23.1 Etiology Pasteurella multocida serotypes (including 1, 3, & 4) which vary in pathogenicity. 23.2 Occurrence and Economic Significance World-wide in distribution, pasteurellosis is encountered as an endemic infection in many intensive poultry producing areas and frequently persists as an infection in specific integrations or farms. Mortality occurs in floorhoused replacement commercial laying and breeding stock and extends into mature flocks. Acute outbreaks associated with environmental or managemental stress, may result in depression in egg production. In breeders, reduced mating activity lowers fertility and depresses productivity of flocks as measured by the number of chicks produced by each hen placed. 23.3 Transmission Infection occurs following direct contact between susceptible birds and clinically affected or recovered carriers. Environmental contamination, rodents, and wild birds are sources of indirect infection. Contaminated feed bags, equipment, and the clothing of personnel may introduce infection onto farms or into integrations. Intraflock transmission is enhanced by handling birds for vaccination and weighing and by open watering systems such as troughs and bell drinkers. 23.4 Clinical Signs Morbidity and mortality rates depend on the pathogenicity of the strain and the susceptibility of the flock. Newly introduced infections may result in up to 10% mortality. Prodromal signs are not observed in peracute cases. Chronic infection may be recognized by enlargement of the wattles, lameness caused by arthritis and torticollis (twisted necks) due to otitis interna (infection of the inner ear). 23.5 Pathology Acute cases show enlargement of the spleen and liver with punctate hemorrhages of the viscera including the heart. Subacute cases may show gray granulomatous foci in the liver. Caseous cellulitis of the wattles and seropurulent arthritis may be present in chronic cases.
23.6 Diagnosis Laboratory examination is required to isolate and identify P. multocida from specimens of heart blood, liver, and spleen. In acute cases, characteristic bipolar organisms may be observed in Giemsa-stained smears of heart blood. 23.7 Treatment Tetracycline incorporated into feed at a level of 200 - 400 g/ton or in water at 250 - 500 mg/l will suppress clinical signs and reduce mortality. 23.8 Prevention Stringent biosecurity procedures are necessary to prevent introduction of infection. Eradication of rodents is critical to reducing the exposure of flocks to P. multocida. Immunization of flocks in endemic areas is recommended. Routine vaccination is essential on farms where previous cases have occurred. Live-attenuated P. multocida vaccines (CU; PM-1; PM-9 strains) are administered by wing-web stab twice during the rearing period, at approximately 10 and 14 weeks of age. Breeder males or flocks subjected to environmental stress may be vaccinated with the relatively milder PM1 and PM-9 strains in place of the CU strain to avoid adverse vaccine reaction. Antibiotics should not be administered one week before and one week after administration of a live attenuated vaccine. Inactivated vaccines can be used to protect flocks if an undesirable reaction to a live vaccine occurs. It is emphasized that for effective control of pasteurellosis inactivated bacterins must be homologous with the endemic strains of P. multocida. In some areas or integrations, autogenous, inactivated vaccines are required.
Enlargement of the wattle due to Pasteurella multocida infection.
Characteristic bipolar staining Pasteurella multocida organisms in a Giemsa-stained blood smear.
Torticollis in a hen which might be due to infection of the inner ear by E. coli or Pasteurella multocida. This change is also observed in flocks exposed to velogenic Newcastle disease.
24.0 SPIROCHETOSIS 24.1 Etiology A spirochete, Borrelia anserina. 24.2 Occurrence and Economic Significance Spirochetosis is widespread in tropical countries due to the prevalence of the soft-shell tick vector Argas spp. The condition is responsible for sporadic losses in subsistence flocks and small scale commercial units. 24.3 Transmission Ticks of the genus Argus are most frequently implicated in transmission of spirochetosis. Studies have confirmed that mites including Dermanyssus spp and Culex spp mosquitoes may also be involved in transmission. 24.4 Clinical Signs Young birds are apparently more susceptible than older stock. Acutely affected birds show depression with cyanosis (blue discoloration) of the head. Mortality may attain 30% of the flock. In sub-acute and chronic cases, birds show paresis (weakness) terminating in paralysis and death. 24.5 Pathology A grossly enlarged spleen with mottling due to subcapsular hemorrhage is the predominant lesion. Focal necrotic hepatitis may also be present. 24.6 Diagnosis Demonstration of the organisms in Giemsa-stained blood smears. The pathogen can be propagated from a spleen homogenate injected into the yolk sac of embryonated eggs at the 6th day of incubation. 24.7 Treatment Oxytetracycline by injection (1-2 mg/kg body weight) or chlortetracycline in drinking water are effective. 24.8 Prevention Eradication of vectors and dusting birds at frequent intervals with 5% carbamate (Sevin®) powder. In some countries, locally prepared vaccines are available but vary in efficacy.
This is important in differentiating AE from encephalomalacia.14 week period. Lymphoid aggregations are observed in the proventriculus. Commercial ELISA test kits are available to monitor the antibody titer of flocks to determine susceptibility or following vaccination or challenge. 25. 124 . 25. 25. Epidemic tremor virus can be isolated from brain tissue by inoculation of embryonated SPF eggs.2 Occurrence and Economic Significance Avian encephalomyelitis (AE) occurs world-wide. resulting in an asymptomatic egg production decline in commercial layers and breeders and elevated mortality in vertically infected batches of chicks. pancreas and other organs.7 Prevention A live-attenuated vaccine can be administered to replacement commercial laying and breeding stock during the 10 .4 Clinical Signs Mortality occurs in chicks aged 3 . 25. Infection of susceptible breeder or commercial egg flocks results in an asymptomatic decline in egg production.25.5 Pathology No gross lesions are observed.6 Diagnosis Histological examination of brain and spinal cord tissue reveals perivascular cuffing and degeneration of neurons. especially in areas where AE vaccination is an accepted practice.1 Etiology: A picornavirus 25. Morbidity varies according to transmission rate but seldom exceeds 5% under commercial conditions. Affected chicks show depression progressing to prostration in lateral recumbency. 25.3 Transmission Vertical transmission occurs by transviral passage of virus from viremic hens to their progeny. chicks demonstrate fine muscular tremors of the head.0 AVIAN ENCEPHALOMYELITIS synonyms Epidemic tremor. Terminally. Recovered birds may show lenticular opacity (cataracts). and feet. Lateral spread from birds which shed AE virus in feces results in direct and indirect infection of susceptible flocks. neck. AE 25.20 days.
wing-web stab route. (Courtesy AAAP) 125 . Lateral spread of vaccine virus will result in a drop in egg production in susceptible hens and mild outbreaks of epidemic tremor in progeny.Vaccines are available for administration in drinking water or as a combination product with avian pox using the intradermal. 98. For the same reason. avitaminosis A. Care should be taken to avoid introducing AE vaccine onto multi-age breeder farms. pullets should not be vaccinated after 12 weeks of age since intestinal shedding of vaccine virus can occur for at least 4 weeks following vaccination. nutritional encephalomalacia or arenavirus infection (Spiking Mortality Syndrome). Incoordination and lateral recumbency in a chick which may be due to avian encephalomyelitis. Detailed laboratory examination including histopathology is required to obtain an accurate diagnosis.
26.2 Pathology Mild inflammation of the tracheal mucosa is observed following primary infection. inclusion body hepatitis and hydropericardium-hepatitis syndrome (HHS) in chickens. 26.1 Clinical Signs Mild respiratory signs (moist rales) occur in a few birds in a flock following infection.3 Transmission All adenoviruses are potentially transmitted by the vertical route. Asia. Under commercial conditions. Inclusion body hepatitis and mild adenoviral respiratory infection may occur in all areas where commercial chickens are reared. This infection has not been diagnosed in the USA and Canada.4 Adenoviral Respiratory Infection 26. 26. and Latin America.4. The condition is characterized by slow onset and spread within and among flocks. Vaccines produced using infected. equipment and housing. Africa. non-SPF embryos have been implicated in outbreaks of EDS and HHS in Asia.2 Occurrence and Economic Significance Egg drop syndrome in mature flocks occurs in Europe. Indirect infection is possible on contaminated personnel. Egg-drop syndrome in chickens.4. 26. 126 . and Latin America and is emerging as a significant restraint to production in areas where intercurrent problems of immunosuppression due to vvIBD and vvMD occur. Pakistan (Angara disease). 26. Hemorrhagic enteritis of turkeys. Hydropericardium-Hepatitis syndrome is responsible for severe losses in India (Lychee disease). direct transmission occurs from fecal shedders to susceptible flocks.0 ADENOVIRAL INFECTIONS 26.1 Etiology Type 1 adenovirus: Type 2 adenovirus: Type 3 adenovirus: Different strains produce specific conditions including mild respiratory infections.
4 Prevention No specific vaccine is available. characterized by enlargement of the kidneys and urate retention may be observed in chronic cases.5.20%) morbidity and slightly elevated mortality occur in broilers and replacement rearing and breeding flocks aged 2 . Affected birds are depressed.4 Prevention All-in-all-out placement programs and appropriate biosecurity procedures are recommended.5. no specific clinical abnormalities can be detected following direct or indirect exposure to EDS virus. morbidity and mortality may exceed 10%. No specific vaccine is available. Eggs produced by brown and tinted-shelled strains show 127 .5 Inclusion Body Hepatitis 26. The more severe HHS infection is characterized by hydropericardium and focal hepatic necrosis.6 weeks. 26. Effective control of Marek's disease and IBD together with early exposure of breeders to mild prevalent adenoviral strains have contributed to a decline in the severity of adenoviral inclusion body hepatitis in broiler flocks in the USA. with ruffled plumage and are disinclined to move.6 Egg Drop Syndrome 26. 26.1 Clinical Signs Moderate (5 . Specific inactivated oil-emulsion HHS vaccines are available for administration in endemic areas.3 Diagnosis Histological examination of affected livers often shows intranuclear inclusions. 26. In the presence of intercurrent immunosuppressive viruses. with mottling due to petechial hemorrhages under the capsule interspersed with areas of necrosis.5. Adenovirus can be isolated from the respiratory and digestive tracts by inoculating embryonated SPF eggs.5.2 Lesions Enlargement of the liver. 26. 26.4. No specific clinical signs are demonstrated.3 Diagnosis Isolation and identification of the causal agent using SPF eggs.26.4. Nephrosis. 26.6.1 Clinical Signs Other than acute drop in egg production in mature flocks.
128 . Confirmation of a diagnosis is based on demonstrating a rise in antibody titer in paired sera applying VN or ELISA procedures. 26. 26.3 Diagnosis Isolation of the causal virus in duck eggs or on liver cell tissue culture.lack of pigment and shells have a "chalky" appearance. Histological changes in the oviduct occur following infection.4 Prevention Vaccination of immature breeding and laying flocks with an inactivated oil-emulsion vaccine is recommended before onset of production.2 Lesions Examination of sacrificed. Failure to attain peak production may be associated with activation of latent infection or lateral introduction of infection at onset of sexual maturity.6. clinically unaffected birds will show regression of the ovary.6.6. 26.
Characteristic hydropericardium associated with Angara disease. 129 .99. 100. Characteristic mottled appearance of liver (subcapsular hemorrhage) associated with Adenoviral hepatitis infections including HHS.
0 RUNTING SYNDROME synonyms Malabsorption. through 30 days of age.27. It is not possible to reproduce the typical stunting syndrome by administering reovirus isolates from field cases. Examination of the orange-colored. loose droppings from infected birds shows the presence of undigested grain particles. 27. 27. suggesting a multifactorial etiology. 27.3 Transmission The reovirus presumed to be responsible for the condition is transmitted by the vertical route from infected hens to progeny in addition to lateral infection among broiler chicks. It is known that reovirus infection can remain latent in replacement pullets during the rearing stage with viremia appearing at the onset of production and persisting for approximately 4 to 6 weeks thereafter. affected chicks which may comprise up to 25% of the flock may weigh only 250 g and are less than half the size of normal pen mates. By 4 weeks of age.4 Clinical Signs Affected chicks show decreased growth rate which is evident by the 5th to 7th day of brooding. A high proportion of affected birds show a disinclination to walk due to a rickets-like syndrome characterized by osteopenia. although most poultry health professionals accept that specific reovirus strains (including 1733) are responsible for the condition.2 Occurrence and Economic Significance The condition has been diagnosed in most broiler-raising areas and is responsible for decreased growth rate and elevated mortality in broiler chicks usually derived from young parent flocks. Abnormal wing feathering gives rise to the term "helicopter disease" since the abnormal feathers resemble rotor blades. possibly in association with as yet unidentified viruses or anaerobic bacteria in the intestinal tract. It is noted that the condition can be reproduced by infecting specific-pathogen free chicks with intestinal homogenates from affected birds. Feather abnormalities are obvious in affected chicks and include breakage of the shafts of the primary feathers of the wings and persistence of yellow down on the head. Infectious Stunting Syndrome 27.1 Etiology: The specific causal agents responsible for Stunting Syndrome have not been identified. The severity and prevalence of the condition generally abates within 1 to 2 years after initial appearance in an area. In extreme cases fracture of the proximal epiphysis of the 130 .
6 Diagnosis A diagnosis of stunting syndrome is based on the history of young parent flocks producing affected chicks and the appearance of up to 20% stunting in a flock with typical clinical presentation in affected birds ranging in age from 7 to 35 days. 27. Affected chicks can be gathered from the flocks at approximately 10 days of age and placed in a common pen where they can be provided with feed and water and protected from competition from normal pen-mates. beading of the ribs. Stunted chicks will grow slowly. Enlargement of the pancreas may be noted. enteritis is not a primary lesion although affected birds may be concurrently infected with coccidiosis or may undergo secondary bacterial infection. there is no definitive laboratory diagnostic procedure. A wide range of pathogens can be isolated from affected flocks. 27. The following components should be considered: • levels of methionine and lysine should attain or exceed breed specifications 131 . Despite obvious malabsorption.5 Pathology Stunting syndrome attributed to malabsorption is characterized by a wide range abnormalities including: • A rickets-like syndrome involving decreased skeletal density. osteopenia resulting in fracture of the proximal epiphysis of the femur (incorrectly termed "femoral head necrosis"). Affected birds show decreased pigmentation of the skin which is evident on the shanks and beak. These changes which are observed clinically are confirmed on post-mortem examination. Isolation of affected chicks may reduce the probability of lateral transmission of virus. Evaluation of dietary formulations is advised to ensure nutritional adequacy. • Pale colored skin and feather abnormalities. 27.femur occurs. Since the range of etiologic agents have not been identified. There are no characteristic gross or histological lesions associated with the stunting syndrome. and can be salvaged for live-bird sale or processing as lowweight birds.7 Treatment There is no specific treatment for stunting syndrome.
• vitamin E supplementation should conform to NRC levels for stressed flocks (20 IU/kg) All supplementary fats and animal byproducts should be stabilized with 300-600 ppm ethoxyquin or an equivalent compound. 27.8 Prevention It is recommended that parent-level pullets receive an attenuated reoviral arthritis vaccine at 7 days followed by a multivalent live vaccine during the 14 to 30 day period consistent with the immunization program for the area.3 ppm.1 to 0. with at least half of this dietary contribution in the form of selenomethionine.• selenium level should range from 0. 132 . Inactivated reoviral vaccines administered during the late rearing period should contain antigenic components which are known to be protective against the reovirus strains (1733) considered responsible for stunting-malabsorption syndrome.
Birds infected with E.2 Occurrence and Economic Significance Coccidiosis occurs world-wide and is a major cause of mortality and suboptimal growth and feed conversion efficiency in immature flocks unless appropriate preventive measures are implemented.1 Etiology Various Eimeria spp which parasitize specific portions of the intestinal tract of chickens. E. 28. Infected. contaminated equipment. 28. mivati: 1-2mm areas of hemorrhage interspersed with white foci visible through the serosa of the distal duodenum and proximal jejunum. E. The cost of anticoccidial feed additives and treatment is estimated to exceed $400 million annually in all poultry producing areas of the world. • immunosuppression (Marek's disease. recovered chickens shed oocysts representing a problem in multi-age operations. by wind spreading poultry-house dust and litter over short distances. 28. • environmental and managemental stress such as overstocking. maxima: distention of the mid-jejunum with hemorrhages in the mucosa. Factors contributing to outbreaks of clinical coccidiosis include:• litter moisture content exceeding 30% due to ingress of rain or leaking waterers. or in some cases. tenella show pallor of the comb and wattles and blood-stained cecal droppings. Oocysts can be transmitted mechanically on the clothing and footwear of personnel. E.3 Transmission The sporulated oocyst is the infective stage of the life-cycle. necatrix: severe distention of the mid-jejunum with hemorrhages in the mucosa and red-stained fluid in the lumen. 134 . acervulina and E. ruffled plumage. inadequate ventilation. mycotoxins) • suboptimal inclusion of anticoccidials or incomplete distribution (poor mixing) in feed. and diarrhea.28. tenella: hemorrhagic typhlitis (inflammation of the cecum).5 Lesions E. 28. inoperative feeding systems.0 COCCIDIOSIS 28.4 Clinical Signs Coccidiosis is generally acute in onset and is characterized by depression. IBD.
• Litter samples for oocyst counts. To confirm a diagnosis in a commercial operation the following specimens should be submitted to a laboratory: • Intestine from a sacrificed. • Providing adequate feeding space. 28. Administration of water dispersable vitamin A and K supplements may enhance recovery. 28. brunetti are diagnostic. 0. • Intestine showing gross lesions in 10% formalin for histological examination. • Chemical and ionophoric anticoccidials for broilers in shuttle programs.1% for 2 days. • Acceptable ventilation rate. Fibrinonecrotic enteritis may occur in chronic cases. • Synthetic coccidiostats for breeders and floor-reared commercial eggproduction flocks which allow the development of premunity. • Maintaining recommended stocking density.05% for 4 days or commercial combinations of sulfa drugs) in drinking water. 0.024% of the active ingredient in drinking water for 3 .5 days. tenella. • Inclusion of anticoccidials in diets at recommended levels will prevent clinical infection.7 Treatment Administration of amprolium solution. This approach is cost-effective but requires experienced and 135 . 0. Microscopic examination of intestinal and cecal scrapings reveals oocysts.6 Diagnosis Gross lesions of E. brunetti: hemorrhages of the mucosa of the distal jejunum and colon. E. affected bird preserved in 5% potassium dichromate for culture and identification of Eimeria sp. necatrix and E. • Representative feed samples for anticoccidial assay. Sulfonamides (sulfamethazines .8 Prevention Management procedures which limit saturation of litter include: • Appropriate installation and management of watering systems.E. 28. Anticoccidial vaccines are appropriate for replacement breeding stock and roasters. Nipple drinkers reduce spillage of water onto litter compared to bell and trough drinkers.
101. (Courtesy AAAP) 136 . Administration of a vaccine (Coxabic®) derived from gametocytes to replacement pullets has been shown to confer immunity to progeny. Careful examination of intestinal tracts from at least 5 clinically normal sacrificed birds per flock is necessary to monitor for coccidiosis. obviating the need for anticoccidials. Future control measures will include in ovo vaccination of broiler embryos with a highly purified oocyst suspension (Inovocox®). Intraocular administration by spray or the insertion of a gelatine cylinder impregnated with oocysts in the chick delivery box contributes to an even distribution of vaccine through the flock. Severe Eimeria tenella infection showing hemorrhagic ceca.diligent management and monitoring especially if the vaccine is applied over feed. 102.
W. AAAP slide set). 137 . Obvious distention and hemorrhage of the ileum (middle of the intestinal tract) due to infection with Eimeria necatrix. 105. Severe Eimeria brunetti lesion in the intestine. proximal and distal to the cecal bifurcation. Lesions of either Eimeria acervulina or E. (Courtesy of Dr. This condition is associated with concurrent Clostridium perfringens enterotoxemia leading to necrotic enteritis. 104. These lesions should be distinguished from the changes caused by Eimeria maxima. Malcolm Reid. mivati infection showing white foci visible through the serosa of the duodenum.103.
Chickens affected with NE develop rigor ("stiffness") within 1 hour of death. 29. Necrotic enteritis is often initiated by an alteration in the feeding program (commencing skip-a-day feeding of replacement breeder pullets or accidental starvation) environmental stress. movement or weighing of flocks.1 Etiology Clostridium perfringens is the principal pathogen responsible for necrotic enteritis (NE) although the condition is multi-factorial in origin and is usually preceded by mild intestinal coccidiosis. Successive flocks in some regions show frequent or persistent outbreaks possibly due to high levels of Clostridium spp in soil or the presence of drug-resistant strains.4 Clinical Signs Mortality is acute with no specific prodromal or clinical signs. There are no characteristic lesions associated with botulism.5 Pathology The mucosa of the intestine shows changes ranging from focal hyperemia (redness) to mucosal ulceration. overstocking. perfringens may be introduced onto farms by deficiencies in hygiene and biosecurity. 138 .3 Transmission Clostridium perfringens and C. 29.2 Occurrence and Economic Significance Both NE and botulism can occur world-wide. but erosive losses of up to 4% can occur in broiler and immature breeder flocks due to direct mortality or concurrent infection with systemic bacteria. The economic significance of clostridial enterotoxemia varies. ruffled plumage and extension of the nictitating membrane over the cornea. botulinum are ubiquitous soil contaminants. Chickens with botulism show ascending paresis and then paralysis extending craniad from the legs. withdrawing anti-coccidial growthstimulating feed additives. impairing locomotion. 29. or saturation of litter.29. an enterotoxemia resulting in progressive paralysis. Pathogenic strains of C. Terminally affected birds are in sternal recumbency with flaccid necks. Ingestion of the vegetative form of the organisms invariably result in colonization of the intestinal tract. in areas where chickens are reared on litter. In extreme cases NE is characterized by extensive pseudomembranous enteritis which resembles a coarse yellow coating. Clostridium botulinum is responsible for botulism. Focal hepatic necrosis may be observed. 29.0 CLOSTRIDIAL ENTEROTOXEMIA 29. vaccination.
29. 29. perfringens can be isolated and identified by a suitably equipped laboratory using anaerobic culture. 139 .5 ml of serum into susceptible mice using the intraperitoneal route. or virginamycin to feed at levels approved by local regulatory authorities will suppress the clinical occurrence of clostridial infections. Losses may reoccur following withdrawal of treatment.8 Prevention Addition of zinc bacitracin. virginamycin or penicillin for 72 hours reduces morbidity and mortality. Botulinum toxin can be identified in the blood of severely affected broilers by injecting 0. Toxin results in paralysis and death within 24 hours. lincomycin.7 Treatment Administration of flocks with water soluble zinc bacitracin. lincomycin .29. Cl.6 Diagnosis Histological examination of affected mucosa will demonstrate the presence of characteristic clostridial organisms applying Gram stain. Botulism and NE can be prevented by the management procedures recommended to prevent coccidiosis.
106. Mucosa of the intestine showing lesions characteristic of necrotic enteritis. 107. 140 . Focal ulceration characteristic of clostridial necrotic enteritis.
or ivermectin (where permitted) in drinking water.0 ENDOPARASITES 30. galli infection may reduce egg production in floorhoused breeders and commercial layers. Parasitism can be diagnosed by examination of mucosal scrapings and fecal flotation. In floor-housed breeders and commercial layers reduction in egg production occurs.5 cm ( ) nematode beneath the nictitating membrane of the eye. which reveal characteristic bi-operculated ova. Other nematodes which may be encountered in subsistence or small-scale flocks include: Oxyspirum mansoni – a 1. contorta.30. Cestodiasis results in emaciation in mature flocks. 141 . Death may occur due to intestinal obstruction in birds which are immunosuppressed or are affected by an intercurrent debilitating condition. Syngamus trachea – a 2 cm ( ) nematode in the trachea. 30. especially if severe infestation is exacerbated by malnutrition or immunosuppression.5 cm nematode beneath the mucosa (koilin layer) of the ventriculus.3 Cestodiasis Numerous cestode species may occur in the intestinal tract and can be diagnosed at postmortem or by examination of feces. 30. Treatment Fenbendazole in feed or levamisole or ivermectin (where permitted) in drinking water. Extensive A.1 Capillariasis Infection of the crop (Capillaria contorta) and the intestine (Capillaria obsignata) will result in severe emaciation and mortality in both immature and producing flocks.2 Ascaridiasis Ascaridia galli occurs in the jejunum and Heterakis gallinarum in the cecum. obsignata. Treatment Piperazine. Mucosal thickening and focal enteritis occurs with C. Cheilospirura hamulosa – a 2. Ingluvitis (inflammation of the crop) is associated with C. levamisole. Tetrameres americana – a 3 mm ( ) spherical nematode beneath the mucosa of the proventriculus.
a 4 mm cestode located in the duodenum.a 30 cm cestode of the jejunum resulting in nodular granulomas and catarrhal enteritis. 109.a 25 cm cestode located in the distal jejunum.The most commonly diagnosed cestodes include: Davainea proglottina . Raillietina echinobothridia . Microscopic examination of intestinal scrapings is necessary to determine the presence of endoparasites.a 25 cm cestode located in the distal duodenum and jejunum. Raillietina tetragona . Choanotaenia infundibulum . Filarid parasites are infrequently observed in the body cavity of backyard fowl and exotic birds at post mortem examination. Treatment Niclosamide in feed. 108. 142 .
Severe cestode infestation (Raillietina sp). Severe ascaridiasis may cause obstruction of the intestinal tract. 143 . Presence of Syngamus trachea parasites in the trachea of an infected backyard fowl.110. 112. 111.
• Manganese deficiency results in chondrodystrophy.31.0 SKELETAL DEFORMITIES AND ARTHRITIS 31. This occurs in growing chicks due to decreased formation of bone below the growth plates of the tibiotarsus and tarsometatarsus. • Vitamin D3 (cholecalciferol) deficiency results in rickets in immature flocks housed in controlled environment units. 145 . sometimes with displacement of the gastrocnemius tendon. • Choline and pyridoxine deficiency may result in bilateral enlargement of hock joints. • Thiamine (vitamin B1) deficiency results in an abnormal gait progressing to recumbency and paralysis with hyperextension of the neck. • Riboflavin (vitamin B2) deficiency results in a deformity of the feet termed "curled toe paralysis". • Chondrodystrophy should be differentiated from valgus-varus abnormality of genetic origin. Confirmation of the diagnosis requires analysis of feed to determine manganese content. bilateral involvement of the hock joints and reduction in length of the long bones. • Pyridoxine (vitamin B6) deficiency results in abnormal gait and convulsions. Chondrodystrophy is characterized by a high prevalence in the flock. Dietary level should range from 80 to 120 ppm for optimal growth.1 Nutritional Etiology • Calcium or phosphorus deficiency or an imbalance in these nutrients will result in rickets in immature birds or osteomalacia in mature breeders and commercial egg-production flocks. The lesion progresses to severe deformation of the hock joint culminating in displacement of the gastrocnemius (Achilles) tendon (perosis). This condition can also occur following administration of toxic levels of nitrofurans to immature flocks. Mildly affected chickens show stunting and enlargement of the hock joint with reduction in the length of the leg bones.
The condition can be diagnosed by serology (ELISA or plate agglutination test for flock screening.2 Infectious Etiology 31. Transmission Vertical transmission is the principal route of infection. refer to the mycoplasmosis section under respiratory diseases. 31. Lateral spread from infected carrier chick occurs. synoviae.1 Mycoplasmosis Mycoplasma synoviae results in serous arthritis. AAAP slide set) 31. Occurrence and Economic Significance Viral arthritis occurs world-wide and is responsible for losses in both commercial broilers and replacement breeding stock. especially during the first 48 hours after hatch. distortion of the ribs and enlargement of the costocondral junctions. Lesions of rickets showing.113.2. For information on diagnosis. indirect transmission is possible through contaminated equipment and from improperly cleaned housing. bending of the tibiotarsus. and hemagglutination inhibition for confirmation) or identifying the organism in synovial fluid by culture or by applying PCR technology. Riddell.2. (Courtesy of Dr.2 Reoviral Arthritis Specific serotypes (S1133 and WVU 2937) are responsible for arthritis and tenosynovitis. Under commercial conditions. Clinical Signs Affected birds aged approximately 30 days onwards show an increasing prevalence of lameness characterized by unilateral or bilateral arthritis of 146 . treatment and control of M. C.
the hock and stifle joints.3 Staphylococcal Arthritis Etiology Staphylococcus aureus is a primary pathogen but often occurs as an opportunist. following reoviral arthritis or mycoplasmosis. Prevention Breeding stock and broilers should be obtained from parent flocks immunized against reoviral arthritis. Breeding flocks should be immunized at approximately 4-5 days of age with a mild attenuated reoviral arthritis vaccine administered by the parental route. and if required. especially involving the hock and gastrocnemius tendon. Up to 10% of the flock may be affected and lame birds generally die from dehydration or persecution.2. The extent of the lesion progresses from acute inflammation to chronic fibrosis. Chronic cases show fibrosis of the tendon sheaths which can be palpated in birds which have recovered from the infection. at mid-cycle. High levels of biosecurity including operation of all-in all-out placement programs will prevent lateral transmission. Retrospective serological diagnosis is based on ELISA assay of serum from acute phase and recovered flocks. Histopathology of affected tissues shows lymphocytic infiltration and reticular cell proliferation. Diagnosis The causal organism can be isolated from synovial (joint and tendon) fluid. Pathology Both serous arthritis and teno-synovitis are observed. This should be followed by a second dose of less-attenuated vaccine at approximately 30 to 40 days of age. and may be responsible for losses in hens at onset of sexual maturity. High levels of parental immunity for breeders is stimulated by administration of an inactivated emulsion vaccine prior to point of lay. Rupture of the tendon occurs in severe cases. Occurrence and Economic Significance The condition occurs world-wide but is a problem in specific broiler breeder flocks subject to immune suppression or previous exposure to reoviral arthritis. 31. 147 .
Affected birds are characterized by unilateral or bilateral hock arthritis and occasionally pododermatitis. aureus as a secondary infection. from 40 weeks of age onwards. Needles used to vaccinate flocks should be sterilized before use and after administering vaccine to 50 consecutive birds.3 Pododermatitis Etiology This condition which occurs in mature broiler breeders. aureus. Immunosuppressive disease should be controlled by appropriate biosecurity including isolation of flocks and vaccination of breeders. 31. Clinical Appearance Increasing incidence of lameness occurs from 8 to 16 weeks and losses may attain 20% of the flock. to reduce the probability of direct inoculation with S. aureus occurs through skin abrasions and lacerations and is often a consequence of parenteral vaccination with contaminated needles or contact with improperly cleaned equipment used for weighing. Occurrence and Economic Significance Pododermatitis is responsible for lameness resulting in death and lowered fertility in broiler breeder flocks. Acceptable biosecurity procedures including decontamination of houses and equipment are recommended. Diagnosis Diagnosis is based on isolation and identification of S. Pathology Affected joints yield purulent. Prevention Purchase of Ms-free stock and effective vaccination against reoviral arthritis will reduce the occurrence S. Treatment Parental administration of antibiotics to infected birds is only palliative.Transmission Introduction of S. Concurrent diagnostic procedure should include serology and culture to determine the possibility of previous exposure to reovirus or M. aureus. Predisposing factors include wet litter and obesity. 148 . is multi-factorial in etiology. Culling of crippled birds is recommended. synoviae. viscous yellow or green exudate. Affected birds invariably die of dehydration and persecution. and is not cost effective.
) • Limestone should have less than 3% magnesium content. • Vitamin premixes should contain acceptable levels of potent D3. free of ammonia reduces damage to foot pads. Areas requiring specific attention include:• Calcium and phosphorus levels in the diet should be in accordance with breed specifications. iron. • Essential amino acid content must conform to breed specifications.1 Alleviation of Locomotory Problems Through Nutrition Changes in dietary formulation will alleviate specific nutritional deficiencies but will have no effect on genetic. The incidence of pododermatitis has decreased in the USA since the introduction of separate male and female feeding systems for broiler breeders. • Water should conform to acceptable standards of purity and mineral content.4% to 0. • Ingredients should not contain mycotoxins at toxic levels.3. • Trace mineral premixes should contain adequate levels of zinc. biotin. The initial lesion is a superficial erosion which progresses to ulceration of the plantar skin with abscessation and chronic fibrosis of underlying synovial structures. Pathology The lesion is characterized histologically by fibrosis. 31. quality control of ingredients and feed in the event of acute episodes of locomotory dysfunction involving a high proportion of a flock.5% available phosphorus for immature flocks. Pododermatitis is characterized by gross enlargement of the foot pad. Implementing post-peak feed restriction is necessary to restrict the weight of both males and females within limits recommended by the supplier of breeding stock.0% calcium and 0. It is advisable to review formulations. Ionophore toxicity results in paresis and paralysis in chicks. 149 . Prevention Dry litter. environmental or infectious causes of locomotory abnormalities.Clinical Appearance Males are more frequently affected than females. (Usually 1. and riboflavin. manganese. presumably due to their relatively higher weight. • Anticoccidial levels must conform to accepted inclusion rates.
Enlargement of the hock joint characteristic of the arthritis caused by reoviral infection or Mycoplasma synoviae. Serous arthritis associated with reoviral arthritis or Mycoplasma synoviae infection. Characteristic "hocksitting" posture of broiler with Mycoplasma synoviae arthritis. (Courtesy AAAP) 150 .114. (Courtesy AAAP) 116. (Courtesy AAAP) 115.
118.117. 151 . 119. Viral arthritis leads to inflammation of the tendon sheath characterized by the presence of serous exudate and hemorrhage. Serous arthritis associated with reoviral arthritis or Mycoplasma synoviae infection. Purulent arthritis attributed to Staphylococcus aureus infection.
120. C.4.4 Developmental Etiology 31. Generally they are not regarded as a significant cause of losses. The long bones (tibiotarsus and tarsometatarsus) show obvious defects in 0. 31.1 Twisted Legs Valgus (x-legged) and Varus (bow-legged) deformities occur in rapidly growing broilers. Valgus and varus deformities are genetic in origin but severity may be influenced by intercurrent nutritional and managemental factors.4. AAAP slide set) 152 . (Courtesy of Dr.31.5% to 2% of broilers in otherwise normal flocks.2 Rotated Tibia and Crooked Toes These changes are observed in turkeys and heavy broilers and are probably genetic in origin. Riddell. Tibial dyschondroplasia lesion in the proximal end plate of the tibiotarsus. The condition can be detected at approximately 3 weeks of age and progresses from angular deformation to displacement of the gastrocnemius (Achilles) tendon.
chicken-strain virus vaccine administered at approximately 8 weeks of age. Mild respiratory rales (sounds) may occur in broiler flocks especially with suboptimal ventilation due to tracheitis. Infection of susceptible mature commercial-egg and breeder flocks results in a decline in production.6 Diagnosis Cutaneous lesions are characteristic. black scab-like lesions.0 mm diameter. Broilers are frequently affected by the diphtheritic form of the infection. 32. 32.2 Occurrence and Economic Significance The disease occurs in most countries with warm and humid climates. Histological examination of affected tissue will confirm the presence of intracytoplasmic inclusions (Bollinger bodies) in the respiratory mucosa and skin. These foci enlarge to become 0.5 Pathology Histological examination shows characteristic intracytoplasmic inclusion bodies in infected skin and tracheal mucosa.1 Etiology: An avipoxvirus.3 Transmission The virus is mosquito-borne. Direct intraflock transmission by contact between infected and susceptible birds may occur. the age of vaccination 154 . 32.4 Clinical Signs Pink focal lesions occur on the comb and wattles and non-feathered portions of the body. Chickens which die of diphtheritic pox may show a plug of desquamated epithelium which lodge in the glottis resulting in asphyxiation.5 to 1. which persist for up to two weeks followed by desquamation and healing. The diphtheritic form is recognized by the presence of nodular hyperplasia of the mucosa of the pharynx and trachea. 32.0 AVIAN POX 32. In areas where early exposure occurs. 32. 32. Broilers may show confluent and extensive lesions of the back especially in the slow-feathering males of the autosexing strains.7 Prevention Immunization is recommended in endemic areas using a mild-attenuated avipox.32. Losses are associated with a depression in growth rate and downgrading due to dermatitis although avian pox does not result in primary mortality.
In some areas. In areas where flocks are affected with vertically transmitted mycoplasmosis. 155 . adverse vaccine reaction from avian pox vaccine can be prevented by administration of a pigeon-pox vaccine. broilers are routinely vaccinated against avian pox by subcutaneous injection at day-old. 121. The efficacy of this procedure is questionable based on demonstrated maternal antibody interference. Focal lesion of avian pox on the comb of a hen.can be advanced.
Only approved insecticides should be applied to poultry or used in the vicinity of housing to avoid contamination of the food chain. Cages and housing can be treated with 2 .33. The gross appearance of the lesion is pathognomonic. Dermanyssus mites parasitize chickens nocturnally. Argasid ticks are nocturnal feeders and favor the soft unfeathered skin beneath the wings.5 Treatment Ectoparasites may be treated with a carbamate insecticide such as Sevin®. 33. applied as a 5% powder to birds at two week intervals.0 ECTOPARASITES 33. Heavy mite infestation is characterized by anemia and the appearance of black mite exoskeleton casts and excreta and dermatitis in the vicinity of the vent. Mature adults are evident on examination. Ticks transmit spirochetosis. 33.1 Mites Ornithonyssus spp remain on chickens permanently. The diagnosis may be confirmed by microscopic examination of detritus from scales 33.7% carbamate suspension administered by spray. 156 .43 Scaly Leg Mites Chronic infestation of the legs of free-roaming chickens with Knemidocoptes mutans results in proliferation of scales overlying the shanks and feet. Insecticides should be used in accordance with manufacturers' label instructions.2 Argasid Ticks Soft-shelled ticks (Argas spp) occur in tropical areas and may affect cagehoused laying flocks or birds maintained on litter. Parasitized birds show multiple hematomas associated with feeding sites. Egg clusters ("nits") are observed as spherical white structures adherent to the shafts of feathers.4 Lice Lice are frequently encountered in subsistence flocks. 33. Lice are responsible for irritation and damage to feathers.
124. Deposit of louse eggs ("nits") on the shafts of feathers. 123.122. Lice are frequently present in backyard flocks and may depress production if infestation is severe. Blood-sucking Ornithonyssus spp mite. 157 .
feather debris. 127. Severe infestation with Ornithonyssus spp mites in the region of the vent showing eggs. Ticks of the genus Argus are vectors of spirochetosis.125. 158 . and excreta. 126. Subcutaneous hemorrhage on de-feathered carcass due to nocturnal feeding of Argas spp ticks.
128. Scaly-leg mite. (Knemidocoptes mutans) 129. Advanced dermatitis of the feet ("scaly leg") due to Knemidocoptes mutans infestation. 159 .
160 .1 Etiology: Fungi including Trichophyton spp. 1% tincture of iodine. spreading progressively. especially in young birds.0 DERMATOMYCOSIS synonyms Favus or "Ringworm" 34. 34.34. Histological examination of Gridley-stained tissue will show characteristic hyphae.6 Treatment Application of a 2% quaternary ammonium disinfectant. 34. 34.7 Prevention Biosecurity precautions should be implemented to avoid introducing infected birds to the flock. Transport crates and other equipment should be thoroughly decontaminated and disinfected to prevent lateral transmission of the agent.2 Occurrence and Economic Significance The condition occurs infrequently in commercial flocks but occurs mainly in subsistence chickens. 34. 34.5 Diagnosis The causal fungus can be cultured from lesions using Sabourauds dextrose agar. or 5% formalin will eliminate the infection. Feather loss may occur if lesions extend to the neck and body of the bird.3 Transmission The fungus is spread by direct contact or by contaminated cages or transport coops.4 Clinical Signs Grey to white scaly lesions appear on the comb and wattles. 34.
(Courtesy of the University of Georgia) 161 . Dermatomycosis (favus or ring worm) characterized by gray scaly appearance of the comb. wattles. and nonfeathered areas of the head.130.
but age. Maize with moisture levels over 13% may be contaminated with mycotoxins including aflatoxin. a widespread problem in the poultry industry is caused by ingestion of toxins produced by molds which contaminate cereals and some oilseeds before and subsequent to harvest. immune response. feed conversion. Specific mycotoxins may product characteristic lesions in affected flocks: • Fusarium T-2 toxin is associated with stomatitis (ulceration of the lining of the oral mucosa). Aflatoxins. Generally. Prevention is based on detection of contaminated ingredients and exclusion from diets if this is practical or financially justified.35. rice. and duration of ingestion. and carcass quality. and peanut meal are most frequently implicated in cases of mycotoxicosis. suboptimal feed conversion. Mycotoxins are a diverse group of chemical compounds which adversely affect liveability. The acute and chronic effects of mycotoxins depend on the type of compounds present. 163 . and low egg production in breeders and commercial egg flocks. Immature chickens and ducklings are most susceptible to mycotoxins. egg production. trichothecenes. Low levels produce economically significant reduction in growth rate and feed conversion in broilers. egg production or hatchability.0 MYCOTOXICOSES Mycotoxicosis. and rubratoxins may result in high mortality if lethal levels of these compounds are present in feed. intercurrent health and environmental stress also influence the response to various toxins in feed. ochratoxins. level of contamination. wheat. • Chronic aflatoxicosis is responsible for cirrhosis of the liver and ascites. immunosuppression. Nutrient content of grain is degraded when mold growth occurs on ingredients even in the absence of mycotoxins. Maize. • Ochratoxin results in kidney degeneration. low-level mycotoxicoses are difficult to diagnose but should always be considered in cases of a chronic decline in growth rate. growth rate.
inhibiting absorbtion. Pale liver of bird receiving 200 ppb aflatoxin in feed (right) compared to liver of bird receiving low level 164 .Correct storage of ingredients prevents post-harvest proliferation of molds. 131. Contaminated corn showing severe fungal infection. Clay compounds may be contaminated with dioxins. Zeolites have limited ability to inactivate other mycotoxins including the fusariotoxins. Salvage of feed contaminated with aflatoxin is possible using high temperature ammoniation or adding commercial aluminosilicates to diets. Charcoal and clay additives are generally ineffective as mycotoxins binders. Zeolite compounds and extracts from the cell wall of Saccharomyces cerevisiae (Mycosorb®) specifically bind aflatoxin in the intestine. 132. Feed additive inhibitors such as propionate and gentian violet will suppress proliferation of fungi and elaboration of toxins.
133. Fred Hoerr) 165 . Fred Hoerr) 135. Stomatitis following consumption of T2 fusariotoxin (courtesy of Dr. 134. (Courtesy of Dr. mycosis or avitaminosis A. Detailed examination of the oropharynx as necessary to exclude conditions such as T2 fusariotoxicosis. Chick showing stomatitis attributed to T2 fusariotoxicosis.
Commercial test kits are available to monitor for the presence of mycotoxins. 166 . Fred Hoerr) 137. Fred Hoerr) 138. Compare with normal plumage on right (Courtesy of Dr. Abnormal feather formation (left) due to fusariotoxicosis.136. Diarrhea in chick fed fusariotoxin (Courtesy of Dr.
167 .139. Water proportioners should be calibrated and their operation should be monitored. Water proportioner can be used to distribute antibiotics and other medication through the drinking system. Monitoring ingredients in feed for the presence of mycotoxins is a necessary quality control procedure. 140.
168 . caulleryi occurs in chickens and L. splenomegaly and hepatomegaly.4 Clinical Signs Flock morbidity may exceed 25% in broilers and replacement egg production flocks. 36. 36.1 Etiology Protozoa of the genus Leucocytozoon. Introduction of infection into a susceptible breeders or commercial egg-flocks may result in variable reduction in egg production. Clinical signs include depression and decreased feed intake. Affected flocks show depressed growth rate and elevated mortality which may be influenced by immuno-suppression and intercurrent primary viral and secondary bacterial infection. Batches of ducklings and goslings may show up to 35% mortality. Gametocytes are elongated structures with prominent nuclei. 36. L.36. 36. 36.3 Transmission Leucocytozoon is transmitted by dipterids of the genera Simulium and Culicoides.8 Prevention Control of insect vectors should be attempted using approved insecticides and draining of standing water.7 Treatment Pyrimethamine in combination with sulfadimethoxine. 36.0 LEUCOCYTOZOONOSIS 36. Muscular incoordination occurs in extremis.2 Occurrence and Economic Significance Leucocytozoonosis is frequently encountered in tropical countries especially where farms are located near lakes or ponds.5 Pathology Affected birds show anemia. 36. Exclusion of insect vectors in open-sided houses is impossible. Schizonts may be observed in preparations of kidney and liver tissue processed with Romanowski stain.6 Diagnosis Identification of the gametocytes which occur as extra-erythrocytic parasites in stained bloodsmear preparations. simondi in waterfowl in Asia.
141. NOTE: In many countries. leucocytozoonosis is referred to incorrectly as "malaria. 169 ." Malaria caused by Hemaproteus spp are not associated with clinical infections in commercial chickens. Leucocytozoon parasite visible as extra-erythrocytic structure in Giemsa-stained blood smear.Clopidol anticoccidial incorporated in feed at levels ranging from 125 to 250 ppm has been used in the USA to prevent leucocytozoonosis in turkeys.
The infection is responsible for severe losses in susceptible flocks.37. Concentration of ducks in intensive production areas and common use of ponds by commercial flocks and migratory and free-living resident waterfowl predisposes to infection.1 Etiology A herpes virus. Clinical signs in mature ducks composed paresis.4 Clinical Signs Morbidity varies according to the strain of virus and the susceptibility of the flock and may range from 10% to 100% with a corresponding mortality rate. • Free blood in the lumen of the intestine.5 Pathology Characteristic lesions of duck viral enteritis include: • Free blood in the body cavity.3 Transmission Duck viral enteritis is transmitted directly by contact of susceptible birds with infected viremic ducks or recovered carriers.2 Occurrence and Economic Significance Duck viral entertitis occurs in all areas where ducks and geese are raised. tremors of the head and limbs. pericardium and capsule of the liver which are evident as petechiae and ecchymoses. 37. • Hemorrhages of the ovary in mature ducks. diarrhea and photophobia. 171 . Highly pathogenic strains of the virus may cause hemorrhages from the nares and cloaca. 37. 37. Affected ducks demonstrate extreme depression. These signs should be differentiated from botulism. • Hemorrhages of the serosa of the intestine. 37. ruffled plumage. Mature breeding flocks show a precipitous decline in egg production immediately preceding a significant rise in mortality. flaccidity of the neck and terminally. Ducks are usually infected from three weeks onwards with an incubation period of 5 to 7 days.0 DUCK VIRAL ENTERITIS synonym "duck plague" DVE 37.
commercial ducks should be isolated from free-living waterfowl which are reservoirs of infection. newly infected and recovered ducks. botulism. 37.6 Diagnosis Characteristic lesions are highly suggestive of the diagnosis. 172 . bursa of Fabricius in ducklings and the annular lymphoid bands (gut associated lymphoid tissue) of the intestine. Where possible. Retrospective diagnosis is based on demonstrating a marked increase in neutralization titers comparing sera from acute. Histological examination discloses the presence of intranuclear inclusion bodies in hepatocytes. 37. 37. Degenerative changes in the intestinal tract extending from the esophagus to the cecum include hemorrhagic areas in the early stages of the disease. 142.8 Prevention A live attenuated chicken-embryo derived vaccine has been used in Europe to prevent outbreaks.7 Treatment None.Hemorrhagic changes are observed in all lymphoid tissues including the thymus. progressing to confluent maculae resembling a diphtheritic pseudomembrane reminiscent of clostridial enteritis in chickens. The viral agent can be isolated in 10-day old embryonated duck eggs inoculated by the chorioallantoic route. pasteurellosis and duck viral hepatitis. It is important to differentiate duck viral enteritis from highly pathogenic avian influenza. Hemorrhage from nares and also from cloaca is characteristic of DVE.
38.0 DUCK VIRUS HEPATITIS 38.1 Etiology A picornavirus is responsible for duck virus hepatitis Types 1 and 3.4 Clinical Signs Morbidity in susceptible flocks may range from 50% to 100%.6 Diagnosis The picoronaviruses responsible for duck virus hepatitis can be isolated from livers using 9-day old embryonated SPF chickens inoculated by the allantoic sac route. airsacculitis and peritonitis may be observed. 38. Mortality results in extensive losses especially with intercurrent bacterial infections including chlamydiosis. Rodents serve as reservoir hosts on affected farms. In the presence of chlamydiosis or Riemerella spp infection. Serologic procedures include agar gel diffusion precipitin test.2 Occurrence and Economic Significance Duck virus hepatitis Types 1 and 3 occur in ducklings under 4 weeks of age in all intensive duck-rearing areas of the world. Direct contact between infected and susceptible flocks especially in multiage operations predisposes to disease. with losses of up to 90% in batches under one week of age. Ducklings demonstrate peracute mortality preceded by lateral recumbency and occasionally. This agent is distinct from hepadnavirus (duck hepatitis B). 38. 38.38. declining in severity to under 10% at 4 weeks of age. 38. Mortality is dependent on the age of the flock.3 Transmission Free-living waterfowl introduce the virus. mycotoxicosis and environmental stress. opisthotonos (hyperextension of the neck. virus neutralization in duck embryos and a plaque reduction test to quantify neutralizing antibody. Mortality is exacerbated by intercurrent bacterial infections. An astrovirus-like agent has been implicated in outbreaks of duck virus hepatitis Type 2 in the UK. 173 .5 Pathology The significant lesion comprises enlargement of the liver with punctate or ecchymotic hemorrhages. "stargazing"). Riemerella and E. coli infection.
Where possible. High mortality in newly placed ducklings has a wide differential diagnosis including DVH. An injection of 0.7 Treatment No specific treatment is available.. Breeders can be immunized with a live attenuated chicken-embryo origin vaccine. 174 . 143.5 ml filtered serum is recommended using the intramuscular route. E. salmonellosis. Rodents should be eradicated. coli. Supportive therapy is recommended.38. single-age isolated placement programs should be followed. and Riemerella infection. Some vaccines have shown reversion to virulence when applied to large flocks. 38.8 Prevention Hyperimmune serum from flocks surviving duck viral hepatitis can be administered to ducklings. aspergillosis and mycotoxicosis.
avoiding overcrowding and chilling should be implemented.39. hepatomegaly and splenomegaly are observed.0 DUCKLING SEPTICEMIA 39. salmonellosis and duck virus hepatitis.8 Prevention Managemental interventions including effective sanitation between placements. A live attenuated vaccine against serotypes 1. which is administered to ducklings by the aerosol route or in drinking water at day-old. In some cases. 2 and 5 has been developed. Multivalent or homologous bacterins have been prepared for administration to ducklings at 1 to 2 weeks of age.1 Etiology Riemerella anatipestifer is the principal pathogen responsible for duckling septicemia. pericarditis and fibrinous airsacculitis. 39. ataxia. liver or brain tissue on either blood agar or trypticase soy agar. coli.5 Pathology Septicemic changes characterized by perihepatitis.7 Treatment Supportive therapy and administration of water soluble tetracycline may be attempted. 175 .6 Diagnosis Diagnosis is based on isolation and identification of Rimerella anatipestifer from heart blood. septicemia.2 Occurrence and Economic Significance Duck septicemia occurs in all areas where ducklings are reared commercially. 39. 39. fibrinous meningitis occur. resulting in variable morbidity and mortality during the first two weeks of the brooding period. Concurrent infections include E. 39. 39. 39.4 Clinical Signs Affected ducklings show depression.3 Transmission Direct contact of susceptible ducklings with a contaminated environment. ocular and nasal discharge and respiratory rales. Enrofloxacin can be administered in drinking water at a level of 50 ppm for the first 2 days followed by 25 ppm for 4 subsequent days. especially in ducklings which display nervous signs. 39. Footpad lesions from defective wire floors predispose to percutaneous infection.
2 Occurrence and Economic Significance Outbreaks of chlamydiosis occur in poultry.0 CHLAMYDIOSIS 40.1 Etiology Chlamydia psittaci. 40. throughout the world.6 Diagnosis Diagnosis is confirmed by isolation of the organism from homogenates of organs obtained using sterile necropsy technique. diarrhea. Laboratory techniques include fluorescent antibody detection and retrospective diagnosis using the complement fixation procedure.3 Transmission The disease is transmitted by both acutely infected birds and latent carriers.40. Laboratory host systems include embryonated eggs inoculated by the yolksac route and mice inoculated by the intraperitoneal route. attributed to transmission of virulent strains from indigenous or migratory bird species by direct and indirect contact and presumably by insect vectors. 40. 40.5 Pathology Chlamydiosis should be suspected if the following lesions are observed in waterfowl: • Fibrinous pericarditis and perihepatitis • Hepatomegaly and splenomegaly • Airsacculitis 40. Commercial transport and handling of waterfowl previously in contact with ornamental and companion species may result in outbreaks in distribution centers associated with trade in live birds. 40. Chronic cases show emaciation and chronic respiratory involvement.7 Treatment Commercial duck flocks can be treated by administration of 176 . Infection requires inhalation of viable elementary bodies. 40. an obligatory intracellular organism. Periodic epornitics have been described in commercial operations.4 Clinical Signs Acute infection in young ducks is characterized by ataxia. including waterfowl. This infection is transmitted to humans and is regarded as an important zoonotic infection. purulent ocular and nasal discharge.
Chlamydiosis should be considered in cases of fibrinous peritonitis and airsacculitis.chlortetracycline in feed at a level of 400 grams per ton for a period of up to two weeks. 177 .8 Prevention Appropriate biosecurity procedures should be imposed to prevent transmission from infected reservoirs including companion bird species. and obligatory reporting of outbreaks. It is virtually impossible to control chlamydiosis in multiage flocks with the opportunity for direct and indirect contact. It is necessary to follow statutory requirements regarding withdrawal periods following administration of antibiotic before sale or slaughter of flocks. 144. free-living Psittacines and Colombibormes. 40.
1 CONVERSION OF U. inch = 6.765 m3 Liquid Measure 1 pint = 0. = 25.61 km Square Measure 1 sq.t.p.184 joule Power 1 h. yard = 0.32) Cº = 5/9 x (54) Cº = 30º = 28. = 1000 watts = 1.000 ft.34 h.028 cm3 1 cu. = 22. = 746 watts = 1.57 litres 1 quart = 1.4 g = 0.min. = 21. TO METRIC WEIGHTS AND MEASURES Linear Measure 1 inch = 25.t.32) EXAMPLE: Cº = 5/9 x (86ºF .2 kg 179 . yard = 0.968 B. 1 long ton 1 short ton Temperature Centigrade = 5/9 x (Fahrenheit . inch = 16. = 4.p.914 m 1 mile = 1.4 mm 1 yard = 0.4 kg 50 lb.14 litres 1 US gallon = 3.205 lb = 1000 kg = 2000 lb = 907 kg Fahrenheit = (9/5 x Centigrade) + 32 EXAMPLE: Fº = (9/5 x 30ºC) + 32 Fº = 54 + 32 Fº = 86º Bushel Weight Shelled maize Cracked maize Cottonseed meal Soybeans 56 lb. lb.836 m2 1 acre = 0. 1 kilowatt = 33.4 cm3 1 cu.p.252 calorie = 3.453 kg = 2. watts Cubic Measure 1 cu.8 litres Weight 1 ounce 1 lb. foot = 929 cm2 1 sq. foot = 0.S.u 1 calorie = 0.8 kg 60 lb. = 27.u.01 metric h.41 Ha Heat Units 1 B.41.7 kg 48 lb.45 cm2 1 sq.
31 0.03937 14.02 Reciprocal multiply by 3.u.3048 30. ft.02832 1.281 0.712 2118 0. per sq.07031 4.22 0. ft. Into Calories (kg) Calories (kg) per m2 m3 per second m3 per minute m3 per hour Metres per minute Centimetres per second Force de cheval Millimetres water column kg per cm2 kg per m2 kg per cm3 Multiply by 0. per second Horsepower Inches water column Pounds per sq.03281 0. inch Pounds per sq.5886 3.0139 25.t.Conversion Factors To convert B. ft.968 0.40 0. ft.48 1.699 0.0004719 35. per minute Cu.9863 0.06243 180 . ft.369 0. Cu.250 2.883 16. per minute Ft.u. ft. per minute Cu. per minute Ft. Pounds per cu.2048 0.t. B.
muscular i.muscular s. Injectable (for therapy of individual high-value birds only.2-0.cutaneous s.muscular i. Not for flocks) Ampicillin Erythromycin Gentamycin Levamisole Spectinomycin Streptomycin Sulfadiazine* Tylosin 10 mg/kg 100 mg/kg 0.cutaneous i.5 mg 30 mg/kg 2-5 mg/chick 100 mg/kg 30 mg/kg 10-40 mg/kg i.2 Drug Feed SCHEDULE OF THERAPEUTIC DRUGS Dose Administration Duration (days) Suggested Withdrawal Period (days) Bacitracin methylene disalicylate Chlortetracycline Erythromycin Furazolidone (where permitted) 20-50 g/ton 100-500 g/ton 100-400 g/ton 150-250 g/ton 8-12 g/ton 2 g/ton 200 g/ton 200-400 g/ton 50 g/ton 100-200 g/ton 125 g/ton feed feed feed feed feed feed feed feed feed feed feed feed feed feed continuous 10-14 5-10 7 max. 10-14 continuous 10-14 1 dose 1-10 10-14 10-14 1-5 2-7 continuous none 5 2 10 not used in EU.cutaneous daily daily day old dose day old daily daily daily 5 5 none none none 5 5 none * Not for egg-producing or breeder flocks.cutaneous s.muscular s. or USA none none 5 5 none 3 5 5 20 none Gentian violet Hygromycin B Lincomycin Niclosamide Novobiocin Nystatin Oxytetracycline Sulfadimethoxine* with 800-1000 g/ton ormetroprim Tylosin 200 g/ton Virginiamycin 20 g/ton * Not for egg-producing or breeder flocks. 181 .41.
PRINTED LABEL DIRECTIONS SHOULD BE FOLLOWED. • Observe withdrawal periods for egg-producing and poultry-meat flocks.5 .5 g/l 1 g/l 250-500 mg/l 0. • Monitor clinical response. • The first value in the dose range usually represents the preventive level. 0. Where practical compare with untreated. Ascertain the legal or statutory restraints concerning drug in the area concerned especially for nitrofurans and fluroquinolones.2 g/l or 200 mg/kg body wt. • The availability of commercial forms of these compounds should be determined for the area of operation.1 ml/l 1 . • Comply with species and age restrictions. 182 .1 ml/l 0.Drug Dose Administration Duration (days) Suggested Withdrawal Period (days) 5 5 3 not used in US 5 5 5 not used in US 5 5 5 5 5 5 5 Drinking Water Administration Ampicillin Amprolium 17% Chlortetracycline Dimetridazole* soluble Enrofloxacin 10%* Flumequin 12%* Furaltadone 12%* Levamisole 10% Nitrofurazone sol* 9% Oxytetracycline Piperazine 17% Spectinomycin 25% Sulfamethazine 12% Tylosin 50% 1. exposed controls.10 ml/l 1 g/l drinking water drinking water drinking water drinking water pill individual bird drinking water drinking water drinking water drinking water drinking water drinking water drinking water drinking water drinking water drinking water 2-5 3-5 3 3-5 1 dose 3-5 3-5 2-5 1 dose 2-5 5 3 hours 3 5-7 3 Notes • * Drug to be administered only where permitted by law or the regulations of an importing country.2 ml/l 1 g/l 10 g/l 50 mg/l 1 g/l 1 g/l 5 . • Specific rates of addition to feed and water may vary according to the concentration of the active compound in the commercial presentation. the second figure is the appropriate therapeutic dose. • Select drugs on a cost-effective basis.5 .
Mortality in chicks day old .41.\ Swollen Head Syndrome Vaccine reaction .Staphylococcus sp. feed) Omphalitis 2. Paratyphoid including Salmonella enteritidis Pullorum disease Smothering Toxicity Mortality & morbidity in chicks 10 .10 days Arenavirus infection Aspergillosis Avian encephalomyelitis Mismanagement: (temperature. Mycoplasma synovia Reovirus Botulism Calcium deficiency Cholecalciferol (D3) deficiency Congenital deformities Manganese deficiency Marek's disease Mechanical injury Niacin & choline deficiency Phosphorus deficiency Riboflavin deficiency Spondylolisthesis Tibial dyschondroplasia 4. water.30 days with nervous signs Argas persicus infestation Avian encephalomyelitis Encephalomalacia Infectious bursal disease Mycotoxicosis Newcastle disease Pyridoxine deficiency Thiamine deficiency Toxicity 3. Mortality & morbidity in chicks 20-50 days with locomotory abnormalities Arthritis . Mortality & morbidity in chickens with respiratory signs Adenovirus Type-1 Avian infectious bronchitis Avian influenza Avian pox Coli-septicemia Infectious coryza 183 Infectious laryngotracheitis Mycoplasmosis Newcastle disease Pneumoviral.3 DIFFERENTIAL DIAGNOSES OF AVIAN DISEASES & CONDITIONS ASSOCIATED WITH SPECIFIC AGE GROUPS & TYPES OF COMMERCIAL POULTRY Diseases & Conditions characterized by:1.
Coryza. Na. Adenovirus. Salmonellosis. IB. Pasteurellosis. Conditions resulting in mortality & morbidity encountered predominantly in caged layers Infectious conditions as above:(ILT. Decline in egg production with mortality & morbidity Avian influenza Avian pox Coryza Infectious bronchitis Infectious laryngotracheitis Newcastle disease Pasteurellosis Salmonellosis 8. P) Fatty liver syndrome Vent peck Leucosis complex Water deprivation 184 . Avian encephalomyelitis) Ectoparasitism Mycotoxicosis Endoparasitism Nutritional deficiencies (Ca.Hepatitis syndrome Ascites complex Coccidiosis Coli-septicemia Conjunctivitis Histomoniasis Infectious bursal disease Liver & kidney syndrome Pasteurellosis Salmonellosis Spirochetosis Sudden death syndrome (Right heart failure) Toxicity Ulcerative & necrotic enteritis 6. P. ND. Mortality & morbidity in broilers & pullets (other than with locomotory. Cl deficiency) Water & feed deprivation 7.5. respiratory & nervous signs) Adenoviral hydropericardium . Decline in egg production Asymptomatic or with mild signs & low or inapparent mortality Adenovirus Type-1 Avian encephalomyelitis Avian influenza Infectious bronchitis Newcastle disease Nutrititional (Ca.
Biotin. Conditions associated with subsistence & free-ranging flocks Arthritis Avian pox Candidiasis Cannibalism Coccidiosis Coli-septicemia Ectoparasites Emphysema (trauma) Endoparasite Histomoniasis Lymphoid leucosis Marek's disease Mycoplasmosis Mycotoxicosis Pasteurellosis Pendulous crop Pododermatitis Predator loss Salmonellosis Spirochetosis Thermal injury Toxicity Traumatic ventriculitis Tuberculosis Visceral gout 11. E (Transudative diathesis). Conditions affecting the integument Avian pox Avitaminosis A. Conditions associated with waterfowl Aspergillosis Avian influenza Botulism Chlamydiosis Colibacillosis Duck viral enteritis Duck virus hepatitis & food-borne infections Erysipelas Coccidiosis Ectoparasites Endoparasite Lead poisoning Mytotoxicosis Nutritional deficiencies Pasteurellosis Salmonellosis 185 . Pantothenic acid deficiency Cannibalism/trauma Dermatomycosis Ectoparasites Gangrenous dermatitis/Staph. complex Managemental factors Marek's disease Pasteurellosis .wattle lesion 10.9.
p c. p c.12. w 186 . w c. p w c z. Zoonoses & food-borne infections associated with avian species TYPE OR SPECIES INVOLVED p c. p DISEASE * Avian influenza * Chlamydiosis Tuberculosis * Salmonellosis (food-borne) * Campylobacteriosis (food-borne) * Arboviral encephalitides (including West Nile disease) Listeriosis (food-borne) * Erysipelothrix infection Aspergillosis Histoplasmosis Newcastle disease Sarcosporidiosis Toxoplasmosis Tularemia * Significant disease c – Companion species p – Commercial poultry w – Wild and free-ranging species p p p p z.
4 ABBREVIATIONS AE AI bpm DVE EDS ELISA HHS HPAI IBD ILT MD Mg Ms ND PCR QAT RT-PCR SPF VN vvIBD vvND Avian encephalomyelitis (epidemic tremor) Avian influenza breaths per minute Duck viral enteritis Egg drop syndrome (Type 3 adenovirus infection) Enzyme Linked Immunosorbent Assay Hydrophericardium-hepatitis syndrome (Type 1 adenovirus infection) highly pathogenic avian influenza Infectious bursal disease infectious laryngotracheitis Marek's disease Mycoplasma gallisepticum Mycoplasma synoviae Newcastle disease Polymerase Chain Reaction Quaternary ammonium disinfectant Reverse Transcriptase.41.Polymerase Chain Reaction specific pathogen free Virus neutralization very virulent Infectious bursal disease velogenic viscerotropic Newcastle disease 187 .
87. 172 avian paramyxovirus • 22. 76-77. 135 antibody titer • 13. 51. 105 Connecticut strain of vaccination • 93 convection-ventilated housing • 13. 62. 81. 156. 6. 124-125 avian influenza • 1. 135-136. 155. 74. 177 blood plate agglutination test • 112. 5. 156 dermatitis • 61. 90. 4. 132. 128. 47. 24. 59. 145. 26-30. 171. 148. 113. 113. 60. 108 bursal disease virus • 3. 88. 115. 39. 176 all-in-all-out • 46. 148 decreased pigmentation • 131 deficiency • 15. 149 ammoniation • 164 amprolium • 61. 156 dermatomycosis • 160 diarrhea • 72. 16 cresols • 26. 8. 106 biological potency • 56 biological transmission • 21 biosecurity • 3. 173 Adenoviral Infections • 126-128 administration of vaccines • 22. 127. 172 Clostridium perfringens • 138 coccidiosis • 8. 106. 176 diphtheritic • 154. 127 aluminosilicates • 164 ammonia • 105. 138. 105. 93. 9. 127. 175. 56. 138. 61 B bacillary white diarrhea (BWD) • 72. 26. 22. 145 choline • 145 chondrodystrophy • 61. 102. 156 arthritis • 95. 145 cyanosis • 84. 117. 120 cestodiasis • 141 chemical antagonists • 57 chicken anemia virus • 22. 93. 85. 60. 105. 123. 23-24. 154-155 Avibirnaviruses • 72 Avipoxvirus • 154 Avitaminosis • 58. 9. 108 Caseous cellulitis • 120 Caseous sinusitis • 99 caseous typhlitis • 112 cataracts • 124 cellulitis • 99. 79. 24. 117. 79 avian pox • 125. 38.INDEX A A picornavirus • 124. 80. 173. 72-74. 88. 9. 51. 73. 96. 85. 131. 139 colibacillosis • 96 conceptual biosecurity • see biosecurity conjunctivitis • 58. blue wing • 76 Bollinger bodies • 154 Borrelia anserina • 123 break-even point • 7 bursa of Fabricius • 73. 164 airsacculitis • 73. 100. 154. 87-90. 160. 97. 174. 54 drug resistant pathogens • 39 duck viral enteritis • 29. 145 chronic sinusitis • 99 circulating antibodies • 35 clostridial enterotoxemia • 138-139. 172. 46. 28. 114. 76. 22. 81. 120. 128 Argas • 22. 148. 60. 53. 108. 95. 88. 35. 106 Bursaplex(r) • 73 butylated hydroxy toluene • 58 C C. 74. 57. 134-136. 121. 107. 4. 108. 154. 22. 84. 147. 80. 35. 94. 124. 112. 123 D dealers in live poultry • 22 decontamination • 4. 147. 22. 30. 112. 172 disease-surveillance program • 47 disinfection • 24. 59. 28. 145 Dermanyssus • 123. 46. 90. 29. 30. 39. 106. 171-172 dyspnoea • 84 188 . 23. 27. obsignata • 141 cannibalism • 62 Capillaria contorta • 141 Capillariasis • 141 carbamate insecticide • 27. chlortetracycline • 123. 123. 168 chlorination • 106 chlorine • 26. crooked toes • 152 curled toe paralysis • 61. aflatoxins • 108. 115. 76. 96. 176 autoxidation • 58 avian coronavirus • 93 avian encephalomyelitis • 60. 70. 114. 80. 175. 126. 105. 48. 62. 28. 175. 77. 125. 61. 132. 15. 70. 53. 121. 35. 57. 156 caseous airsacculitis • 106. 154 ataxia • 58. 112 benefit-to-cost ratio • 6. 37. 163 aspergillosis • 54. 163. 21. 146-148 Ascaridia galli • 141 Ascaridiasis • 141 ascites • 101. 172 bursal atrophy • 72. 108. 124. 134. 58. 37. 177 cholecalciferol • 59. 47. 99. 29. 96. 96. 100. 101-102 Aspergillus fumigatus • 101 asphyxiation • 84. 74. 14.
coli • 8. 160 ivermectin • 141 J jejunum • 134. 106. 88. 155 mycotoxicosis • 163. 76. 126. 76. 135. 147. 172 iodine • 56. 106. 117. 70. 126. 93. 4. 9. 21. 141. 135. 81. 108 furazolidone • 109. 131 M malacia • 60 manganese deficiency • 56. 155 Mechanical transmission • 21. 172 hemorrhagic tracheitis • 84 hemorrhagic typhlitis • 134 Heterakis gallinarum • 141 Highly pathogenic avian influenza (HPAI) • 3. 93 formalin • 26. 105. tenella • 134. 154 gross marginal analysis • 8 H H-120 strain IB • 93 Haemophilus paragallinarum • 99 helicopter disease • 130 hemagglutination inhibition • 81. 156 mosquito • 22. 46. 61. 146 hemorrhagic syndrome • 60. 106. 108. 109. 21. 154 mucosal scrapings • 138. 9. 108. 171-172 epidemic tremor • 60. 57. 127 infectious bronchitis • 7. 102. 132 evaporative cooling • 13. 88. 135 E. 109 fogger nozzles • 15 fomites • 79. 3. 148 mycoplasmosis • 3. 141 muscular dystrophy • 60 muscular tremors • 124 Mycoplasma gallisepticum • 95. 127.E Egg-drop syndrome • 126. 73. 160 I inclusion body hepatitis • 126. 135 ELISA • 38. 69. 80. 173. 28. 131. 51. 124-125 epidemiology • 2. 28. 74. 138 hyperpnea • 13 hyphae • 101. 51. 80. 87. 175 E maxima • 134 E. 172 laryngotracheitis • 8. 73. necatrix • 134 E. 134 Massachusetts strain • 93 maternal antibody • 35-36. 88. 141. 93. 93. 124. 138. 117 G gangrenous dermatitis • 76 gastrocnemius (Achilles) tendon • 62. 37. 80. 149 Marek's disease • 22. 96. 96. 109 ethoxyquin • 58. 123. 87. 81. 81 levamisole • 141 lice • 156 lincomycin • 139 linolenic acid • 56 lysine • 56. 79. 147 encephalitis • 101 encephalomalacia • 59. 127-128 Eimeria • 134. 145. 8. acervulina • 134 E brunetti • 135 E. 106. 146. 96 Mycoplasma synoviae • 95. 142. 21. 88. 93. 43. 134 mesogenic virus • 79. 173 N nephrosis • 127 net present value (NPV) • 6 neuraminidase • 87 189 . 59. 142 L facial cellulitis • 99. 74. 131 mite infestation • 123. 84. 128. 60. 95. 100.14. 73. 116. 96. 135. 96. 81 methionine deficiency • 56. 174 intramuscular injection • 38 intranuclear inclusion bodies • 84. 114. 146. 127. 85. 160 fowl cholera • 120 fowl typhoid • 114-115 free radicals • 58. 15 F Hitchner • 81 hydropericardium-hepatitis syndrome (HHS) • 126 hyperemia • 84. 84 LaSota • 81 lentogenic • 79. 147. 89. 1527 gentian violet • 164 glottis • 84. 105. 176 fluoroquinolone • 96. 146. 93 infectious bursal disease virus (IBDV) • see bursal disease ingluvitis • 141 intracytoplasmic inclusion bodies • 154 intramuscular route • 37. 124 endogenous heat production • 13 endothelium • 59 enteritis • 116. 58. 57. 120 fatty liver syndrome • 58 Favus or "ringworm" • 160 fecal flotation • 141 femoral head necrosis • 131 fenbendazole • 141 fixed costs • 7-8 fluorescent antibody technique • 84. 145. 94.
147. 76. 21. 22. 53 stunting • 3. 106. 135 nitrofurans • 145 nits • 156 O ochratoxins • 163 ocular discharge • 93. 106. 28. 28. 84. 156 split-cycle rearing and laying • 47 squamous metaplasia • 59 Staphylococcal arthritis • 147 Staphylococcus aureus • 147 star gazing • 61 stomatitis • 163 structural biosecurity • 4. 126. 145 oxidative rancidity • 58. 149. 29. 139. 112. 123. 108. 84. 22. 116. 123. 80. 88. 114. 174 rodenticides • 29 rotated Tibia • 59. 100. 113. 46. 85. 51. 106. 135. 152 rubratoxins • 163 runting syndrome • 130 S Sabouraud's dextrose agar • 101. 80. 60. 51. 127 190 . 175 penicillin • 139 pericarditis • 108 perihepatitis • 106. 116. 160 Salmonella enteritidis • 21. 61. 47. 47. 145 sulfamethazine • 135 sulfonamides • 99. 88. 108. 145 Q Quaternary ammonium compounds • 26. 99. 27. 160 R rales • 93. 147 serums • 13. 145 tibiotarsus • 61. 22. 28. 69. 132 selenomethionine • 60. 105. 81. 96. 130. 116 pulmonary congestion • 80. 131. 99. 123. 35. 105-107 synovitis • 95 T tarsometatarsus • 61. 99. 26. 46. 79. 149 parathyroid glands • 59. 108. 80. 120 pasteurellosis • 3. 136 oophoritis • 114 operational biosecurity • 4. 39. 60. 38. 147. 76. 131. 84. 123. 112 Salmonella spp • 21. 114. 121. 61. 105. 70. 123. 171 Pasteurella multocida • 28. 61 paratyphoid • 21. 61. 130. 43 selenium • 56. 24. 124. 76. 130. 175. 89. 145 tenosynovitis • 146. 59. 154. 88. 131. 47. 175 reovirus • 3. 149 rickets • 59. 22. 21. 145. 148 riboflavin • 61. 24. 84. 116. 120. 175 seropurulent arthritis • 120 serous arthritis • 96. 96 propionate • 164 prothrombin time • 60 proventriculus • 69. 145. 145. 121. 171. 146. 105. 23. 117 Salmonella gallinarum • 114 Salmonella pullorum • 21. 109. 113. 29. 53 organophosphate toxicity • 60 Ornithobacterium rhinotracheale • 105 Ornithonyssus • 156 orthomyxoviruses • 87 osteomalacia • 59. 152 tetracycline • 100. 108 pyridoxine • 60. 21. 112. 69. 38. 116 oocyst • 134.Niclosamide • 142 Nipple drinkers • 106. 115. 173 perosis • 62 petechial hemorrhages • 127 phenols • 26 piperazine • 141 pododermatitis • 148-149 polymerase chain reaction • 76. 90. 116-117 paresis • 59. 84. 174 serum plate agglutination test • 96 serum-virus neutralization • 81. 88 single-stage setters • 54 skip-a-day feeding • 138 slipped tendon • 62 spirochetosis • 22. 152 torticollis • 120 tracheitis • 80. 135 swollen head syndrome • 3. 175 thiamine • 60. 120. 139. 147. 172 pathogens • 21. 24. 88. 112. 23. 95. 121. 113. 138. 8. 51. 173. 131. 112. 138. 132 septicemia • 8. 35. 59 oxytetracycline • 123 P Pad cooling • 15 paralysis • 59. 132. 51. 22. 54. 105. 28. 72. 61. 117 salmonella typhimurium • 28. 114. 61. 138. 176 omphalitis • 21. 141 pseudomembranous enteritis • 138 pullorum disease • 21. 47. 145 rigor • 138 rodents • 4. 95. 95. 108 peritonitis • 106. 154 transudative diathesis • 59 Trichophyton • 160 turkey rhinotracheitis virus • 105 tylosin • 96 U urate retention • 59. 130. 73. 28.
51. 120. 9. 6. 93. 124. 35. 97. 145. 136. 148. 90. 76. 22. 88. 88. 134. 160 white diarrhea • 72. 61. 38. 46. 48. 154 valgus-varus abnormality • 145. 130 virginamycin • 139 visceral gout • 59. 154. 149 W wattles • 15. 60. 106. 152 velogenic • 9. 112 X xerophthalmia • 58 Z zinc bacitracin • 139 191 . 59. 138. 36. 128. 132. 135. 89. 39.V vaccination • 3. 37. 107. 54. 72 viral malabsorption syndrome • 57. 70. 61. 74. 79-80 very virulent (vv) pathogenic vvIBD • 37. 8. 21. 79. 81. 121. 120. 69 vitamin deficiency • 58.
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