Noble goals, unforeseen consequences: control of tropical diseases in colonial Central Africa and the iatrogenic transmission of blood-borne viruses

BACKGROUND In southern Cameroon, 40-50% of individuals born before 1945 have antibodies against hepatitis C virus (HCV), suggesting massive iatrogenic transmission of at least one blood-borne virus in the region of the world where SIV(cpz) emerged into HIV-1. OBJECTIVE To estimate the potential role of disease control programs that used intravenous (IV) drugs in the transmission of blood-borne viruses, especially HCV. METHODS We reviewed, for 1921-1959, records of health services in Cameroun, Oubangui-Chari, Gabon and Moyen-Congo. We calculated the incidence of diseases whose treatment required the administration of IV drugs, and compared these with previously published data on HCV prevalence. RESULTS Several IV drugs were used against African trypanosomiasis, leprosy, yaws and syphilis. However, yaws was the only disease whose incidence was high enough so that up to half of some birth cohorts could have acquired HCV. Yaws incidence varied dramatically between regions, and was often > 200 per 1000 per year in southern Cameroon, where extremely high HCV prevalence was found. Yaws incidence peaked between 1935 and 1955, a period which coincided with the emergence of HCV and HIV. CONCLUSION Age, geographical and temporal distributions of yaws suggest that the HCV epidemic in Cameroon was driven by campaigns against yaws (and, secondarily, syphilis) using arsenicals and other metallic drugs. The same interventions may have exponentially amplified other blood-borne viruses, including SIV(cpz)/HIV-1.