THE EPIDEMIOLOGY AND PROPHYLAXIS OF HEPATITIS-B IN SUB-SAHARAN AFRICA- A VIEW FROM TROPICAL AND SUBTROPICAL AFRICA

There are approximately 50 million chronic carriers of hepatitis B vir us (HBV) in Africa, with a 25% mortality risk. In sub-Saharan Africa, carrier rates range from 9-20%. Many studies have suggested that HBV t ransmission in Africa occurs predominantly in childhood, by the horizo ntal rather than the perinatal route. The exact mode of transmission i s uncertain but probably involves percutaneous infection through saliv a or traces of blood, as well through unsterile needles, tribal scarif ication, and other possible vehicles. Compared with adult HBsAg carrie rs in the Far East, those in Africa have a low rate of HBeAg positivit y, which may account for the relatively low rates of perinatal infecti on. It is also possible that African infants are less susceptible to p erinatal HBV infection compared with their Asian counterparts. Alterna tively, it may be that African infants are indeed infected with HBV at birth but, for genetically determined reasons, have persistently nega tive tests for a number of years until the virus is reactivated. In vi ew of the high HBV carrier rates in the general population, universal immunisation of all infants is recommended. Ways of incorporating the hepatitis B vaccine into the Expanded Programme on Immunisation in eac h country are being evaluated.