Risk factors for hepatitis C virus transmission in colonial Cameroon.

BACKGROUND: In southern Cameroon, where SIV(cpz), the source of human immunodeficiency virus 1 (HIV-1) group M, is prevalent among wild chimpanzees, approximately 50% of some human birth cohorts have been infected with hepatitis C virus (HCV) through unclear mechanisms. METHODS: To evaluate indirectly the hypothesis that medical interventions contributed to the early emergence of HIV-1, we conducted a cross-sectional study of 451 inhabitants of Ebolowa in southern Cameroon aged 60 years, using HCV as a marker of parenteral transmission of blood-borne viruses. We administered a questionnaire and tested serum for antibodies against HCV. Viral gene sequences were obtained from HCV-positive sera. Molecular clock analyses provided an independent source of information on epidemic history. RESULTS: A total of 252 participants (56%) were HCV seropositive. HCV sequences were amplified and genotyped from 171 individuals. Independent risk factors for HCV seropositivity were older age, having received intravenous treatment against malaria, and having attended an ethnic school (women only), whereas having been circumcised by a traditional practitioner (men only) tended to be associated with HCV. In addition, transfusions were associated with HCV genotype 1 transmission. Molecular clock analyses of HCV genotypes 1, 2, and 4 revealed that each independently underwent exponential growth during the first half of the 20th century. CONCLUSIONS: Medical interventions (intravenous antimalarial drugs, transfusions) and to a lesser extent traditional practices (circumcision) were associated with the massive transmission of HCV among this population decades ago. This finding supports the hypothesis that medical interventions contributed to the transmission of blood-borne viruses, perhaps including SIV(cpz) and HIV-1, in the same region during the early 20th century.