Socio-geographical patterns of HIV-1 transmission in Kagera Region, Tanzania.

A population-based study on the prevalence of HIV-1 infection in the Kagera region was performed in 1987. The study was based on a multistage cluster sampling technique covering the age-group 15-54 years. The study showed considerable variation of prevalence of HIV-1 infection in the areas studied. A total of 2475 adults were studied and the overall prevalence of HIV-1 infection in the region was 9.6% with a higher prevalence in the urban area (24.2%) compared to that in the rural areas (4.9%). In the present analysis, information on individuals collected during the prevalence study has been used to characterize smaller geographical areas of several villages (wards) and to form the basis for an aggregated analysis of geographical and social patterns relevant to HIV-1 transmission in the studied areas of the region. Kagera region is a heterogeneous society with respect to, for example, religion, ethnic groups and family patterns. There was a moderately strong positive correlation between HIV-1 prevalence and frequent change of sexual partners on the ward level. In Bukoba town the prevalence varied remarkably among the wards, with the lowest prevalence in the ward having the highest social status. In the rural areas, however, the prevalence in the wards decreased considerably with increasing distance from Bukoba town. This aggregated analysis of socio-geographical patterns of HIV-1 transmission characteristics has provided us with information for prioritizing areas of HIV/AIDS intervention in the Kagera community.