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What is Occurence of disease in excess of expected frequency is known as - and explain in detail?
Ans. is `b' i.e., Epidemic disease Epidemic The unusual occurrence in a community or region of disease, specific health-related behaviour (e.g., smoking) or other related events clearly in excess of expected frequency (expected occurrence). o The key words in the definition of epidemic are "in excess of expected occurrence" (for expected occurence frequency see above explanation). o The amount of disease occuring in the past, in the absence of an epidemic, defines expected frequency. So, when disease occurs in expected frequency in the absence of epidemic --> Endemic disease. o When conditions are ourable for disease agent, it may occur in excess of expected occurrence, i.e., endemic disease bursts into epidemic. o If normal expectancy is zero, even one case is considered epidemics. That means occurence of new disease in a community is an epidemic. Similarly reoccurrence of an eradicated/eliminated disease is an epidemic. Statistically speaking, epidemic is said to occur when number of cases exceed 'twice the standard detion' Some times term outbreak is used. for a small, usually localized epidemic. o Diseases causing epidemics are measles, chickenpox, and cholera. o Besides these there is modern slow epidemic of non-communicable diseases like CHD. Pandemic o An epidemic usually affecting a large propoion of population over a large geographic area such as a nation, e.g., influenza, Cholera El Tor and acute hemorrhagic conjuctivitis. Ecdemic o Disease that originates outside the geographic area in which it occurs. Sporadic o The cases occur irregularly, haphazardly from time to time ,and generally infrequently. o The cases are so few and separated widely in space and time that they show little or no connection with each other, nor a recognizable common source of infection. o Examples - Polio, Tetanus, meningococcal meningitis, Herpes Zoster. For easy to remember Sporadic ---> Disease occuring irregularly from time to time. Endemic --> Disease occuring regularly in expected frequency. Epidemic --> Disease occuring in excess of expected frequency. Pandemic --> Epidemic affecting a large propoion of population over a wide geographic area.