The Distribution of Hepatitis B Surface Antigen in Africa and the Tropics: Report of a Population Study in Nigeria

Olumide, E. A. (Department of Preventive and Social Medicine, University College Hospital, Ibadan, Nigeria). The distribution of hepatitis B surface antigen in Africa and the Tropics: report of a population study in Nigeria. International Journal of Epidemiology 1976, 5: 279–289. This preliminary study was designed to examine the distribution of hepatitis B surface antigen (HBsAg) in two contrasting groups in an urban area situated in the tropical forest belt. The sample from the traditional area represents a population of low socio-economic status, living in the central slum areas of the city, and the sample from the peripheral area represents a population of high socio-economic status living in clean modern estates. The prevalence rate of HBsAg by complement fixation (CF) was 12–6 per cent in both areas. There was no statistically significant difference between the two groups with respect to prevalence of the antigen. When both groups were combined, no significant relationship was found between the presence of the antigen and sex, age, marital status, level of education, occupation, income, and a presumed exposure to the antigen from injections, dental treatment, blood tests, surgical operations, blood donations, tribal, ‘medicinal’, tattoo and cosmetic marking, insanitary disposal of faeces, doubtful sources of water supply, and exposure to mosquitoes. No association with genotype was found. For the traditional area only, a significant association was found between the presence of the antigen and the type of latrine in the house, the number of blood tests done within two years of the study, and reception of injections in a dispensary. For the peripheral area only, a lack of protection from mosquitoes was found to be significantly associated with the presence of antigen. The apparently high prevalence of HBsAg in Africa compared with other areas of the world, does not appear to be related only to these factors. World-wide studies aimed at defining the ecology of HBsAg, its subtypes and its antibody (HBsAb), as well as longitudinal studies in children would seem to be indicated. Control measures indicated include protection from the bites of mosquitoes, the need for hygiene in relation to parenteral procedures, and the improvement of methods of sewage disposal particularly in the traditional areas of the city.