Hepatitis B virus infection in two Gambian villages.

The prevalence of hepatitis B virus infection was markedly different in two neighbouring Gambian villages. 62% of children in Manduar aged 2-4 years were infected whereas in Keneba, the other village, only 27% of this age-group were infected. However, in both villages few infants were infected--none under 6 months of age and only 2 of 58 between the ages of 6 and 12 months. Carriage of hepatitis B surface antigen (HBsAg) was high, reaching a peak of 36% in the 5-9 age-group in Manduar and 17.6% in the 2-4 age-group in Keneba. 86% of all the children under the age of five who were HBsAg-positive also carried hepatitis B e antigen (HBeAg). This proportion fell to 17.6% for children aged 10-14 years and to 12.9% for mothers. Infection clustered in families, transmission from sib to sib being of major importance. The chances of a child being an HBsAg carrier were approximately 42% if an elder sib carried the antigen, 27% if either mother or father was a carrier, and 15% if neither mother or father was a carrier. There were 4 HBeAg-positive mothers who were highly infectious, since 10 of 11 of their children became HBsAg carriers. Carriage of surface antigen lasted many years; 63% of those carrying the antigen in 1972 were still positive in late 1980. 4 cases of primary hepatocellular carcinoma out of 672 adults have been diagnosed in the past five years. All 4 were in HBsAg carriers.