The Risks of Yellow Fever to Asian Primates

Infectious diseases are a growing threat to the conservation of nonhuman primates. In the case of diseases shared with humans, the risk is higher where habitat loss and fragmentation facilitate proximity to wildlife. Yellow fever (YF) is an infectious disease transmitted by mosquito vectors between primates in a sylvatic cycle or between humans in an urban cycle. Whereas YF does not compromise the survival of primates in Africa, where the disease is native and endemic, it has caused significant losses in Atlantic Forest primate populations in South America. Given that Asia is free of YF, we anticipate maps of infection risk for 80 species of Asian primates based on biotic and abiotic predictors of YF environmental suitability. Specifically, we used data on climate, forest cover, and the potential distribution of the mosquitoes that act as vectors in YF sylvatic cycles. We found that Malaysia, Singapore, Indonesia, Brunei, and portions of southern India are high-risk zones for the occurrence of the YF virus. Four primate species have their ranges located completely within YF high-risk zones and an additional 44 species include high-risk zones within their distributions. We found that YF is a potential threat to wildlife worldwide, and that Asian primates can become particularly vulnerable if the YF virus is introduced into the region. Given the documented negative effects of YF on primates that are not immune to the disease, we stress the urgency of global control policies, such as mass human vaccination and safer travel protocols, to prevent the spread of the YF virus.