July 22, 2009

Chimps Susceptible To AIDS-Like Disease

It appears that an AIDS-like disease that was considered to be harmless to chimpanzees can infect the apes and kill them as well, researchers reported on Wednesday.

The simian immunodeficiency virus (SIV) is considered to be a precursor virus to the AIDS virus, HIV-1.

SIV comes in various forms, most of which are capable of infecting a variety of monkey species in Africa.

Scientists had previously considered SIV was unable to infect and kill apes in similar fashion to HIV in humans.

However, new research published in the British journal Nature, has uncovered the first evidence showing that apes are vulnerable to the disease.

Researchers studied chimpanzees at Gombe National Park in Tanzania "“ the location where primatologist Jane Goodall and her colleagues have studied the apes for almost 50 years.

Researchers from the Lincoln Park Zoo and University of Illinois combined efforts with the Jane Goodall Institute and the Tanzania National Parks to develop a system to monitor the health of chimpanzees at Gombe.

"We are pleased to see the groundbreaking results coming out of the multidisciplinary epidemiological health monitoring system we've established in Gombe," said veterinary epidemiologist Dominic Travis, vice president of conservation and science at Lincoln Park Zoo and an author on the study.

"This has significance for Gombe chimp health and park management, disease ecology as it relates to retroviral emergence, and to ape conservation as a whole by using Gombe as a laboratory. This field site is once again a model of how long-term scientific studies can inform us in many ways."

The group has monitored the impact of SIV among the chimpanzees at Gombe for nine years. At any one time during this period, between 10 and 20 percent of chimpanzees were SIV-positive, researchers said.

They found that chimpanzees infected with SIV were 10 to 16 times more likely to die than their uninfected counterparts.

They used additional evidence from necropsies performed by veterinary pathologists from the University of Illinois Zoological Pathology Program. They took tissue samples from the chimps to detect the loss of CD4+ T-cells, which are vital to the immune system. Loss of these cells in humans is a primary indicator for HIV-1 infection.

"When I first looked at these samples I was taken aback," said Karen Terio, veterinary pathologist at the University of Illinois.

"Slides from one of the chimps showed extreme lymphatic tissue destruction, and looked just like a sample from a human patient who has died of AIDS."

"Previously, we didn't think SIV could affect chimpanzee population health. Now we know it's possible," said primatologist Elizabeth Lonsdorf of Chicago's Lincoln Park Zoo.

"The next step is to understand this issue better in Gombe to see if it is site-specific, or if it has potential widespread implications for chimpanzee conservation."


Image Caption: Researchers found that chimpanzees that are infected with SIV may suffer an AIDS-like syndrome and die as a result. This chimp, in Lincoln Park Zoo, was not part of the study. Credit: Lincoln Park Zoo


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