Hepatitis B Virus Infection: the Burden of Disease in South Africa

ABSTRACT

Hepatitis B virus infection; both acute and chronic; occurs commonly in the black population of South Africa; and chronic infection and its sequelae of cirrhosis and hepatocellular carcinoma are major public health threats. Chronic hepatitis B virus infection is rare in the other population groups; with the exception of the very small Chinese community. Prevalences of chronic carriage of hepatitis B virus in South African blacks are 5-16in rural males; 8-9in urban males; 4-12in rural females; and 2.7-4in urban females. The overall male to female ratio is 2.61.0. There are now three to four million South African blacks who are chronically infected with this virus. In rural black populations chronic hepatitis B virus infection is acquired very early in life; predominantly as a result of horizontal transmission of the virus; and by the age of 5 years carrier rates approach those seen in adulthood. A further slight increase occurs at school-going age and a greater increase at the time of becoming sexually active. Urban black carrier rates are significantly lower and the infection is acquired later in life. The decreased urban viral carriage rates occur mainly in the first generation born in an urban environment. Hepatitis B virus accounts for about 60of clinically evident acute viral hepatitis among blacks and about 10of chronic hepatitis and cirrhosis. It is the cause of the majority of the many cases of hepatocellular carcinoma that occur in black South Africans. The tumour is more common in males and in rural-born than in urban-born blacks. The close association between chronic hepatitis B virus infection and hepatocellular carcinoma holds true in rural and urban patients and males and females. The association is age-related; being closer in younger patients. Genotypes A and D of hepatitis B virus predominate in South African isolates; with genotype A and its subtype Aa having aparticularly high hepatocarcinogenic potential