SIV and long-term primate health surveillance

1 minute read

Carl Zimmer’s post about simian immunodeficiency virus (“AIDS and the virtues of slow-cooked science”) gives some thoughts about the relation of big-budget lab science and observational natural history and ethology. It took years to determine the long-term health effects of the virus on wild chimpanzees at Gombe, but the results in the end were dramatic:

The results, published today in Nature, are stark. Out of the 94 chimpanzees, 17 had SIV. The SIV-infected chimpanzees had a mortality rate 10 to 16 times higher than the uninfected chimpanzees. Fewer infected female chimpanzees gave birth than uninfected ones, and none of their babies survived to a year. Pathologists found that dead infected chimpanzees looked like they had AIDS, with a lower level of immune cells called CD4+ T cells and damaged lymph tissue.

For humans, some of the biggest early clues about HIV and AIDS were that people died of diseases that were otherwise rare or not deadly, like Kaposi’s sarcoma. But for wild chimpanzees, infectious disease already takes a higher toll at younger ages than in humans. A higher death rate from these causes may not be noticed until you look in detail at infection rates from the virus, which is what this long-term study was able to do.

Given the value of these observations for understanding the origins of human disease, maybe someone should realize that field studies of primates deserve more long-term budgetary support? We have a health research infrastructure that can mobilize hundreds of millions of dollars for studying hundreds of thousands of people longitudinally. We take health statistics on entire nations. But worldwide we have health statistics on only a few thousand non-human primates, and longitudinal studies of health outcomes on only a relative handful. Not only does their pathogen ecology provide an important model for human disease; it increasingly is the same disease pool, as people encroach on wild primate populations.