Journal of virology 2017 03 15() pii 10.1128/JVI.02479-16
Simian T-lymphotropic virus 1 (STLV-1) enters human populations through contact with non-human primate (NHP) bushmeat. We tested whether differences in the extent of contact to STLV-1 infected NHP bushmeat foster regional differences in prevalence of human HTLV-1. Using serological and PCR assays, we screened humans and NHP at two sub-Saharan African sites where subsistence hunting was expected to be less (Taï region, Côte d’Ivoire, CIV) or more developed (Bandundu region, Democratic Republic of the Congo, DRC). Only 0.7% of human participants were infected with HTLV-1 in CIV (N=574), and 1.3% of humans in DRC (N=302). Two of the Ivorian human virus sequences were closely related to simian counterparts, indicating ongoing zoonotic transmission. Multivariate analysis of human demographic parameters and behavior confirmed that participants from CIV were less often exposed to NHP than participants from DRC through direct contact, e.g. butchering. At the same time, numbers of STLV-1 infected NHP were higher at CIV (39%, N=111) than at DRC (23%, N=39). We conclude that a similar ultimate risk of zoonotic STLV-1 transmission – defined as the product of prevalence in local NHP and human rates of contact to fresh NHP carcasses – contributes to the observed comparable rates of HTLV-1 infection in humans in CIV and DRC. We find that young adult men and mature women are most likely exposed to NHP at both sites. In view of the continued difficulties to control zoonotic disease outbreaks, the identification of such high risk groups of NHP exposition may guide future prevention efforts.Importance Multiple studies report a high risk for zoonotic transmission of blood-borne pathogens like retroviruses through contact to NHP, and this risk seems to be particularly high in tropical Africa. Here, we reveal high levels of exposure to NHP bushmeat in two regions of Western and Central tropical Africa. We provide evidence for continued zoonotic origin of HTLV-1 in humans at CIV, and we find that young men and mature women represent risk groups for zoonotic transmission of pathogens from NHP. Identifying such risk groups can contribute to mitigate not only zoonotic STLV-1 transmission, but transmission of any blood-borne pathogen onto humans in sub-Saharan Africa.