Humans may be at greater risk than previously thought from a variety of simian immunodeficiency viruses (SIV) in primate bush meat, according to new research.

A study conducted in Cameroon shows that more than 16 per cent of wild monkeys carry strains of the virus, which is generally believed to be the origin of HIV.

The results suggest that people who hunt and eat monkeys — a common practice in sub-Saharan Africa — could be at risk of developing new forms of HIV, if the primate viruses manage to ‘jump’ into humans, say the researchers.

“The reservoir of these viruses is much more important than was previously thought,” says Eric Delaporte from the French Institute of Research for Development (IRD), one of the authors of the study, to be published in the May issue of Emerging Infectious Diseases.

The study of 800 monkeys also identified five new strains of SIV, and found the virus in four monkey species that had never before been shown to be carriers.

“It is no longer [merely] a supposition that humans are exposed to these viruses,” says another author, Beatrice Hahn of the University of Alabama at Birmingham, United States. “The virus is found in the very primates that humans come into contact with.”

Most HIV/AIDS researchers believe that HIV originated in chimpanzees and made the jump to humans through exposure to primate blood through the hunting and preparing of primate meat.

Although there is no proof that the new viral strains identified in the Cameroon study have been transmitted to humans, previous studies have shown that several types of SIV can replicate in human cells.

“There is a potential risk of recombination between these viruses and, for example, an HIV-1 strain,” says Delaporte. “It could generate new HIV strains”. This could “complicate all fields of HIV care”, he says, from vaccine development to drug response.

The findings are especially worrying because of the growth of the bush meat trade in recent years, and the increasing exploitation of forests, both of which have led to more contact between human populations and wildlife.

The researchers say that more studies are vital to understand the epidemiology of SIV and to investigate possible transmission to humans. “Our future work is to elaborate a screening test based on new strains, to do an epidemiological study and to do in vitro studies to examine the potential pathogenicity of these viruses [in humans],” says Delaporte.

Link to Emerging Infectious Diseases paper (released early)

Photo credit: Robert L. Anderson, USDA Forest Service, Image 1748075. www.forestryimages.org. March 22 2002.

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