Hepatitis-B virus infection in rural and urban populations of eastern Nigeria: prevalence of serological markers.

Hepatitis B virus markers were measured by radioimmunoassay in the sera of 804 rural and urban inhabitants and prisoners in Nigeria. Of these, 530 (66%) subjects had one or more serologic markers of HBV infection; 9.1% were HBsAg carriers, 47% had anti-HBs and 10.1% were positive for anti-HBc alone. Total HBV exposure rate, HBsAg carrier rate and previous exposure to hepatitis B virus measured by the frequency of anti-HBc alone were significantly higher in the rural population compared with the urban population (p less than 0.0001; p less than 0.03; p less than 0.01) respectively. It was observed that by the age of 40 years, 87% of the Nigerian population have at least one HBV seric marker. There was a higher incidence of HBsAg (p less than 0.0001) and anti-HBc alone (p less than 0.001) in prisoners than in any other group. HBeAg was present in 16.4% HBsAg positive individuals with no intersex difference. No positive correlation was found between the frequency of HBV markers in rural dwellers and the history of blood transfusions. These findings suggest that horizontal transmission aided by cultural or behavioural factors and clustering of carriers rather than transfusions is the main determinant of HBV prevalence in rural Nigeria.