Clinical and epidemiological significance of the HBSAg (Australia antigen): carrier state.

One hundred fifteen asymptomatic Australia antigen (HBSAg) carriers, discovered by routine testing of volunteer blood donors in Toronto, were investigated and followed for up to 30 months. The carrier state seems to be largely host-dependent, and its prevalence is modified by ethnic origin, sex, and age. A high prevalence of carriers was found in persons coming from Mediterranean countries and the Orient. The carrier state was 3 times more common in males than in females, and the majority of the carriers were under 30 years of age. Family clustering of HBSAg-positive individuals was observed. All carriers were asymptomatic and only one gave a history of jaundice in the past. Seven gave a history of intravenous drug use. Four had moderate hepatomegaly. Fifty-four had some abnormality in their liver function tests. The SGPT was the most frequently abnormal test and correlated best with the histological findings. Twenty of 29 liver biopsies showed features of chronic benign persisting hepatitis. All patients remained well during the follow-up period. In no patient was there evidence of deterioration or progression in either their clinical state, liver function, or pathological findings. Only 1 of the 115 carriers became HBSAg-negative over the period of observation.