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.