Bushmeat poses threat of simian retrovirus transmission to humans

Epidemiological research from central Africa in this week’s issue of THE LANCET highlights how a new form of retrovirus – simian foamy virus (SFV) – can be transferred from primates to humans as a result of hunting for bush meat. Although the effect of simian foamy viruses on human health is not yet known, authors of the research state that a reduction in hunting and consumption of bushmeat will be necessary to prevent the spread of this retrovirus in humans.

The hunting and butchering of wild primates (eg, monkeys, gorillas, chimpanzees) infected with simian immunodeficiency virus (SIV) is thought to have sparked the HIV pandemic two decades ago. Although SIV and other primate retroviruses infect laboratory workers and zoo workers, retrovirus transmission from animals has not been documented in natural settings.

Nathan Wolfe from Bloomberg School of Public Health, Johns Hopkins University, Baltimore, USA, and colleagues from Cameroon and the USA studied 1800 people from nine rural communities in Cameroon, of whom around 1100 reported that they had been exposed to blood or body fluids of primates from hunting. 1% (10 individuals) of the exposed population had antibodies to SFV. Genetic analysis revealed three geographically independent human SFV infections, each of which was acquired from three different primates.

Dr Wolfe comments: “Our findings show that retroviruses are actively crossing into human populations, and demonstrate that people in central Africa are currently infected with SFV. Contact with non-human primates, such as happens during hunting and butchering, can play a part in the emergence of human retroviruses and the reduction of primate bushmeat hunting has the potential to decrease the frequency of disease emergence”.

In an accompanying Commentary (p 911) Martine Peeters from the Institut de Recherche pour le Dévelopement, Montpellier, France, states: “For foamy viruses, no disease has yet been observed in human beings, human-to-human transmission has not yet been shown, and there are almost no data on the occurrence of foamy viruses in human beings. But if foamy viruses also behave like HIV and human T-lymphotropic virus and produce different diseases when different simian foamy viruses are involved, it cannot be excluded that the pathogenicity of foamy viruses with a particular simian strain might emerge in the human population after a long incubation period, and especially as life expectancy increases. Because of Wolfe and colleagues’ findings, studies will now need to be started to examine whether in these natural settings in Africa human-to human-transmission occurs with foamy viruses and whether any disease is associated with these infections”.