viral hepatitis infections are among the most important public health problems , and hepatitis a virus ( hav ) is the most common cause of acute viral hepatitis worldwide . each year , almost 1.5 million cases of acute hepatitis a infection are reported throughout the world ; however , the results of serological studies indicate a higher number of infected cases . age is one of the important prognostic factors in a clinical course of hepatitis a infection . in communities with low to middle socioeconomic state , the age of infection occurrence is within the childhood period . in many parts of the world including latin america , the age of acquisition of the disease has shifted from childhood to adulthood , which is due to improved health level . although the age of infection occurrence has increased in different communities with the economic advancements and improved level of health , being affected with the disease in higher ages is accompanied with more severe clinical symptoms and even hepatic failure . in such countries , the increased work absence , hospitalization , and even increased mortality therefore , prevention of the disease is of great importance . considering the high costs of vaccination programs , following the development of safe and very effective vaccine and immunoglobulin against hav , a fundamental issue is the determination of target individuals or groups for receiving the vaccine / preventive immunoglobulin . healthcare workers and medical students are among the at - risk groups of the disease . because of the lack of sufficient experience in performing many clinical procedures , and also exposure to blood and body fluids of the patients , medical students are at the risk of the infection and thus its complications . there is a lack of data on the seroprevalence of hav among healthcare team in our society . in one study from north however , to the best of our knowledge , no study , so far , has been carried out to determine the seroprevalence of hav and thus the need for vaccination / preventive immunoglobulin among the medical students in our society . thus , the current study was performed to evaluate the serological prevalence of hepatitis a in 1-year medical students in isfahan , central iran . this cross - sectional study was carried out in 2007 in isfahan , central iran . after explaining the project , all 1-year students of different schools of the isfahan university of medical sciences ( n = 403 ) were invited to participate in the study at the registration day . after obtaining written consent , participants filled out a questionnaire , which included items on demographic characteristics , number of family members , residence place ( dormitory or home ) , type of drinking water ( urban drinking water , rural pipe water , well water ) , history of jaundice and hepatitis , and history of immunoglobulin injection . a blood sample ( 10 ml ) was obtained from each participant under aseptic condition . the samples were kept in the cold box and were sent to the laboratory of isfahan research center of infectious and tropical diseases in <3 h. after centrifugation of the samples , blood sera were extracted and separately kept in microtubes ( aliquots ) at -70c . to evaluate the igg antibody against hav ( hav ab ) , elisa kit ( the kit is competitive- and qualitative - based , and the results obtained were interpreted according to co / s of the samples in od = 450 nm , and with the calibration mentioned in the guidelines of the kit . the cut - off calculation was carried out using the formula : cut - off = ( np + nc ) 3 , and the results were interpreted as follows : < 0.9 was considered negative , 0.91.1 : equivocal , and > 1.1 : positive . finally , the data were analyzed using chi - square and independent t - test , by the spss software , version 16.0 ( spss inc . of the 403 students , 361 ones ( 89.5% ) agreed to participate including 61.1% females , with the mean age of 19.8  2.6 years . those who did not agree to participate were not different from the participants regarding age ( 19.9  2.8 ) , but they were different from the participants with regard to the gender ( 83.3% female ) . univariate analysis showed higher age in seropositive students ( p < 0.001 ) , but no relationship between seropositivity and gender ( p = 0.227 ) . number of family members was significantly higher in seropositive cases ( p < 0.001 ) . furthermore , seropositivity was more frequent in those who used to live in a dormitory ( p = 0.003 ) , and in those with a history of drinking rural pipe water ( p = 0.008 ) , table 1 . frequency distribution of risk factors of hepatitis a considering different factors associated with seropositivity , a binary logistic regression analysis was performed . the results showed that age ( odd ratio [ or ] = 1.49 , confidence interval [ ci ] : 95% : 1.221.82 ) and number of family members ( or = 1.45 , ci : 95% : 1.181.78 ) were independently associated with seropositivity . many cases of hospital infections of hepatitis a have been reported , and the number of occupational infections with hav is increasing . close contact with patients , not observing hygiene points , not wearing gloves when contacting body fluids , eating and drinking in hospital wards , and children fecal contamination may pose healthcare workers at the risk of these infections . the results of our study demonstrated that 75.3% of the medical students in our society had igg antibody against hav at entering the medical college . indeed , one from four students was not immune against hav . to the best of our knowledge , no study in iran has been carried out to determine the prevalence of immunity against hepatitis a in healthcare students . in a similar study in turkey , the seropositivity of medical students was reported to be 64% and another study in delhi found seropositivity in 63% of medical students , which were almost similar to our findings . however , in korea , seropositivity is reported as 11.4% among 1-to 3-year medical school students , and in nursing students in thailand , prevalence of hepatitis a antibody was 8.9% in one study and 17.5% in another study . in another survey from greece , 14.6% of healthcare students these differences between studies are attributed to the geographic differences of hepatitis a seroepidemiology affected by health behaviors and environmental factors , and differences between studies in age of the studied population , as even in the same population , there is a considerable geographic seroepidemiologic difference . we did not find a statistically significant relationship between acquisition of hepatitis a infection and students gender , which is in agreement with the observations of the study performed in turkey and india . moreover , in the study carried out in 2007 in isfahan province , no relationship was found between gender and hepatitis prevalence in the general population . the type of drinking water is another factor that is important in the acquisition of hepatitis a. as expected , we found a relationship between hepatitis a and the type of drinking water . moreover , we found a relationship between the residence place ( home or dormitory ) , and acquisition of hepatitis a. as we included students at the 1 year of their entrance to the college , factors belonging to living in dormitory can not justify this association . indeed , the association can be explained by the observation that medical students used to live in dormitory are from the towns near isfahan , and the difference in prevalence of hepatitis a among inhabitants of isfahan and its neighboring towns has been found in the study on isfahan province general population . perhaps , the residency during childhood is more important but we did not gather such data . the size of the family is another item , which was shown to be related to the prevalence of hepatitis a in our study . our findings in this respect are consistent with those of the previous studies , which indicated that as the size of family increases , the risk of acquisition of the disease increases . the prevalence of hav infection in the developed countries is almost 1%/year of life , and if a case of infection is indentified , all individuals with close contact with the patient in the past 2 weeks must receive gamma globulin . however , in the developing countries , different statistics have been reported with regard to the hav prevalence . a high portion of the population has acquired the infection in the first decade of their life . gamma globulin injection will prevent the acquisition of the infection in the childhood , which has fewer complications . thus , the risk of infection in higher ages , which is accompanied with more severe complications , is increased . in countries like iran , in which most people acquire hav infection in childhood , gamma globulin administration in the second decade of life and especially after the third decade is of no use . furthermore , administration of gamma globulin has high costs and is accompanied with some side - effects . from the economic point of view , a course of vaccination costs three times of performing the screening test ; therefore , the vaccination target group should be selected carefully . according to the recommendations of centers for disease control and prevention , if the frequency of positive cases and presence of immunity in a particular age range is above 33% , and the cost of screening test and its related medical visit is less than one - third of the vaccine price , carrying out the screening test is suggested . a study on cost - effectiveness of vaccination for hepatitis a in healthcare workers in the usa estimated that with vaccination , the incidence of hepatitis a will be reduced by 94% , death from infection by 92.5% , and lost years of life by 94.3% . because the seropositivity of hepatitis a was very high in the population studied , serological screening prior to vaccination might be less cost - effective than the universal vaccination of course , a cost - effectiveness study by data from our own society could provide a more accurate response to this issue . such study needs data on yearly incidence rate and mortality / morbidity of hepatitis a from our society . one out of four medical students in our society is prone to hepatitis a infection and at its age , it could be very serious . therefore , vaccination is suggested for medical students in our society . whether serological screening prior to vaccination is cost - effective needs further evaluation in our society . furthermore , it should be considered that observation of health measures , access to healthy drinking water , and hygiene of residence place , as well as other points of personal and social health can prevent the acquisition of infection .
background : students of medicine are prone to contact with various infectious agents such as hepatitis a virus ( hav ) . 
 infection with hav may lead to morbidity and in rare cases , mortality . 
 we evaluated the seroprevalence of hav among 1st - year medical students to assess the necessity of vaccination / preventive immunoglobulin in this at - risk population.methods:this cross - sectional study was carried out in 2007 among 403 1st - year medical students in isfahan , iran . 
 participants filled out a questionnaire including items on demographic characteristics , medical history , and hygiene . 
 then , the anti - hav igg antibody was assessed using the elisa method ( diagnostic bioprobes , dia - pro , milan , italy).results : among the 403 students invited to attend the study , 361 ones ( 89.5% ) agreed to participate ( 61.1% female ) , with a mean age of 19.8  2.6 years . of the participants , 272 ( 75.3% ) students 
 were seropositive . 
 seropositivity was not associated with gender ( p = 0.222 ) , but was associated with the number of family members ( p < 0.001 ) , residence place ( p = 0.003 ) , age ( p < 0.001 ) , and the type of drinking water ( p = 0.008).conclusions : one of the four medical college students of our society is prone to hepatitis a infection . 
 accordingly , vaccination / preventive immunoglobulin is suggested for this population ; however , whether a prior serological screening is cost - effective needs further evaluation by epidemiologic data from our society .