Hepatitis B virus carrier state in black children in Ovamboland: role of perinatal and horizontal infection.

Hepatitis B surface antigen (HBsAg) was detected in 17% of adult males and 11% of mothers in Ovamboland , South West Africa/Namibia. Hepatitis B e antigen (HBeAg) was present in 15% of HBsAg-positive mothers. Only 1% of children less than 6 months of age were HBsAg-positive, compared with 13% of children over the age of 1 year. 27% of mothers who were HBsAg-positive had HBsAg-positive children, whereas the corresponding figure for mothers who were HBsAg-negative was 6%. 63% of mothers who were positive for both HBsAg and HBeAg had HBsAg-positive children. 37% of HBsAg-positive children had HBsAg-positive mothers, compared with 8% of HBsAg-negative children. Later "horizontal" rather than neonatal maternal-infant transmission of the hepatitis B virus (HBV) seems to be the more important mode of spread of this infection in Ovambo children. The difference in the pattern of transmission of this virus between the Far East and Africa seems to centre mainly on the differences in the HBeAg status of the mothers in these two regions.