Progress towards the comprehensive control of hepatitis B in Africa: a view from South Africa.
The carrier rate of hepatitis B virus (HBV) in black Africans averages 10.4% throughout the continent. Even within each country, however, there may be wide variations. HBV carriage in black Africans is largely established in early childhood, mostly through horizontal transmission. Perinatal transmission also occurs but to a much lesser extent than in the Far East. For unknown reasons, HBeAg positivity rates are much lower in black Africans of childbearing age than in women in the Far East. Universal HBV vaccination of infants in South Africa started in April 1995. Effective integration into the Expanded Programme on Vaccination will probably be necessary if administration of second and third doses is to be ensured. Fortunately, a natural process of urbanisation is also having a beneficial effect on the black carrier rate in South Africa, as urban carrier rates tend to be much lower than those in rural area. Within the next 20 years, therefore, there should be a great reduction in the numbers of acute HBV infections and new carriers. However, it will take much longer before there is any substantial impact on the burden of the longterm sequelae of HBV infection--that is, cirrhosis and hepatocellular carcinoma.