HIV Digest	HIV Digest Archive

A study has found a missing link between a chimpanzee virus and HIV. Scientists had long suspected chimps are the source of HIV because at least one subspecies carries a simian immune deficiency virus closely related to HIV. Because the simian virus, SIVcpz, was identified in chimpanzees in captivity, researchers were not certain the same virus existed among apes in the wild.

Testing hundreds of chimpanzee droppings collected in Cameroon, researchers found that SIVcpz does exist in the wild.

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Researchers theorized that HIV was first transmitted locally somewhere in west-central Africa. The subspecies of chimpanzees, Pan troglodytes troglodytes, in which SIVcpz was found in captivity, lives in the wild in Cameroon, Gabon, and the Congo Republic. Therefore, the first infection could have occurred in any one of those areas.

Wild chimps are reclusive. So, with the permission of the government of Cameroon, researchers asked hunters, members of expeditions, and workers sent by local health officials to collect fecal samples from the forest floor, especially near the base of fruit trees. Investigators collected 599 fecal samples in ten forest sites in the southern part of Cameroon, placing them in test tubes containing a preservative.

When the samples were tested, evidence of SIVcpz infection was found in five of the ten field sites. Prevalence was up to 35 percent in three communities; four and five percent in two communities; and none in five communities.

The communities with a high prevalence of infected chimps were south of the Sangha River, which flows into the Congo River and on to Kinshasa, leading to the theory that some infected person carried HIV from a remote area to Kinshasa, where it was then passed on.

It is not known whether chimps with SIVcpz become ill. More collections are needed in other areas of Africa to provide a clearer picture of the evolution of HIV/AIDS and to determine whether there are other viruses that could cause AIDS-like epidemics.

Editor's Note: from the New York Times