Hepatitis A and B in the family unit. Nonparenteral transmission by asymptomatic children.

Investigation of an outbreak of hepatitis A among members of an adoption organization implicated recently arrived Vietnamese orphans as the source of infection. A serologic study disclosed a 27% prevalence of hepatitis B surface antigen among Vietnamese orphans and a 23.1% (6 of 26) prevalence of hepatitis B antibody among American children of adopting families. Five of the six antibody-positive American children were in families with HBsAg-positive orphans. Thus,healthy orphans from high hepatitis incidence areas may transmit hepatitis B, as well as hepatitis A, in the family unit.