Epidemiology of hepatitis B virus in an institution for mentally retarded persons.

Sera from patients and employees of the Lynchburg Training School and Hospital were tested for Hepatitis B surface antigen by complement fixation test and antibody against Hepatitis B surface antigen by radioimmunoprecipitation test. Hepatitis B surface antigen was detected in 20% of the Down's syndrome patients and 7 percent of the matched other retarded patients. Antibody against Hepatitis B surface antigen was detected in 40% of the Down's syndrome and 57% of the matched other retarded patients. Hepatitis B virus infection as measured by presence of either Hepatitis B surface antigen or antibody was similar in the Down's syndrome patients (59%) and the matched other retarded patients (63%). Male patients had a higher frequency of Hepatitis B surface antigen chronic carriers and a lower frequency of antibodies to Hepatitis B surface antigen than the female patients. No relationship between age at time of first institutionalization and prevalence of Hepatitis B virus infection was demonstrated. However, it was observed that patients institutionalized at an earlier age were more likely to be housed in wards with a high frequency of Hepatitis B surface antigen. Increased length of institutionalization was associated with increased prevalence of Hepatitis B virus infection. Antibody to Hepatitis B surface antigen was detected in 33% of the employees. Employees who worked on wards with a high frequency of Hepatitis B virus infection had a high frequency of Hepatitis B surface antibody (50%) whereas those working on wards with a low frequency of infection had a low frequency of Hepatitis B surface antibody (9%).