Seroprevalence of HIV, hepatitis B, and syphilis in an urban population and isolated villages in Gabon.

Method Using a cluster sampling method, a representative sample of 456 adults living in the town of Franceville (30 000 inhabitants) was compared with the 211 adults living in five gold panning villages in the Nouna area. At the beginning of 1996, sociodemographic characteristics were gathered and a blood sample was taken for testing for the following: (1) HIV—screening by enzyme immunoassay (Genelavia mixt Sanofi-Pasteur, Marnes-la-Coquette, France and Enzygnost Anti-HIV 1⁄2 Plus, Behring, Marburg, Germany). DiVerentiation between HIV-1 and HIV-2 with a third enzyme immunoassay (Multispot HIV-1/ HIV-2, Sanofi-Pasteur, Marnes-la-Coquette, France). (2) Hepatitis B—detection of Ag HBs by enzyme immunoassay (Monolisa Ag HBs, Sanofi-Pasteur, Marnes-laCoquette, France). (3) Syphilis—Treponema pallidum haemagglutination assay (TPHA-kit Biomerieux, Marcy-l’Etoile, France). The data were analysed using the ÷ test, the Fisher’s exact test, and the Mantel– Haenszel ÷ test for stratified analysis. Prevalence was estimated with a confidence interval of 95%. The observed diVerences were considered as significant for an alpha error of 5%. The seroprevalence rates were adjusted by sex.