A population-based serosurvey was conducted to determine the HIV-1 prevalence and to evaluate various risk factors in three parishes in western Uganda. Adults over 14 years were examined in all 13 villages of Kigoyera parish far from Fort Portal, in two villages of Kyamukoka parish closer to Fort Portal and in the four fishing villages of Ntoroko parish at Lake Albert with a high population mobility. Personal interviews and HIV serology using ELISA and Western blot were performed. Sera showing at least two envelope bands in the Western blot were considered as positive. The coverage of the registered eligible population was 74% in Kigoyera, 67% in Kyamukoka and 25% in Ntoroko. The prevalence of HIV was 4% (97 of 2267 persons examined, 95% CI 3.4-5.1%) in Kigoyera, a typical rural area. Whereas it was 13% (53 of 393 persons examined, 95% CI 10.1-16.9%) in Kyamukoka near to the district capital and exceptionally high with 24% (96 of 399 persons examined, 95% CI 19.9-28.3%) in the comparatively isolated fishing villages of Ntoroko. In a multivariate model the infection risk for HIV was in Kyamukoka two and in Ntoroko five times higher than in Kigoyera. Among the two main ethnic groups one had a significantly lower risk to acquire HIV infection than the other group.
Conclusions: Because of their large proportion of migrating persons the fishing villages presented populations with high risks for HIV infection. The ethnic composition of the village population, representing group specific sexual behaviour, was a risk factor for HIV infection.