Hepatitis B virus infection in Chinese families in Hong Kong.

Between January 1983 and July 1984, 731 family members of 240 hepatitis B surface antigen (HBsAg) carriers were screened for hepatitis B virus markers. The percentage of those who were positive for HBsAg was 28.3 and that for antibody to hepatitis B surface antigen/antibody to hepatitis B core antigen was 43.1. The carrier rate was higher among siblings (53%) and offspring (50.5%) of female carriers, but similar to that of the age-matched general population for spouses (10.8%). Maternal transmission was the most important mode of spread of hepatitis B virus infection within the family. The HBsAg-positive offspring and siblings were clustered within certain families. Intrafamilial spread is important in perpetuating hepatitis B virus infection in Chinese persons. Susceptible family members, especially newborns and other young children of female carriers, should be vaccinated.