[Studies on an outbreak of hepatitis A in an institution for the mentally retarded children].

The outbreak of hepatitis A occurred in an institution for the mentally retarded children in Bibai city. Hepatitis A virus infection was observed in 50 of 144 children who were sensitive to HAV (infection rate 34.7%). Clinical findings and severe liver dysfunction were seen in 30 of 50 cases and the rate of apparent infection was 60.0%. The route of infection was thought to be water-borne in bathing or contact infection in each room. Food-borne infection was excluded, as all children had eaten same food. Human serum globulin for protection against hepatitis A was administered and was effective to prevent the manifestation of hepatitis A. The rate of apparent infection was decreased 92.9% (26/28 cases) to 18.1% (4/22 cases) after administration.