Does logging contribute to AIDS deaths in Africa?
Rhett Butler, mongabay.com
June 14, 2008
Human-widlife interactions are an important vector for emerging diseases, especially in the tropics
Thomas R. Gillespie, a researcher at the University of Illinois at Urbana-Champaign, said that primates living in logged and degraded forests in Uganda and Republic of Congo have higher incidence of potential pathogens relative to their counterparts found in undisturbed areas. The findings have implications for human health in that some of these disease agents dramatically increase mortality of people suffering from HIV/AIDS. Since the study areas have high HIV/AIDS infection rates, an increase in the abundance of these disease agents could have significant health impacts.
Analyzing the the abundance, variety and density of potentially harmful parasites in gorillas, chimps and monkeys living in Kibale (Uganda), Bwindi (Uganda), and sites in the Republic of Congo, Gillespie and colleagues found higher prevalence of infection among primates living in distrubed forest areas. In logged areas in the Republic of Congo, the researchers reported the presence of Strongyloides stercoralis, a parasitic roundworm that results in a hyper infection in HIV patients that carries a 98 percent mortality rate. Gillespie said the roundworm — which is not typically found in Central Africa forests and was likely introduced by loggers who defecate on the edges of logging sites — was recorded in 12 percent of plots in logging areas but none of the forest park zones. Still because primates are now being picking up Strongyloides stercoralis, it is possible that infected individuals could move into pristine forest areas, speading the pathogen to unaffected populations.
Young gorilla in Gabon (Photo by Rhett Butler). Gillespie's research has found high anitbiotic resistance among gorillas visited by tourists in Uganda's Bwindi Impenetrable National Park. Anitbiotic resistance among unvisited gorillas was nearly zero.
"Clearly this is bad for people and bad for primates," he said, speaking Thursday during a presentation at the annual meeting for the Association for Tropical Biology and Conservation. "The interface [between primates and humans] is growing as there is less forest habitat and more peple."
Gillespie said researchers have already detected the presence of cryptosporidium — a protozoa originally found only in livestock — in wild monkeys and people near Kibale. In an area with one of the highest HIV/AIDS infection rates on the planet, the potential impact Cryptosporidium — which accounts for 25 percent of AIDS deaths worldwide — is substantial.
Gillespie noted that the growing interaction between humans and wildlife further increases the risk of emerging disease. He cited a recent Nature study that found 60 percent of emerging infectious disease between 1940 to 2004 came from animals. 72 percent of these — including SARS, ebola, HIV-AIDS, SARS, and new strains of influenza — originated in wildlife.
Gillespie said these diseases are also posing a threat to endangered wildlife, especially as their their populations shrink from hunting and their habitats contract from logging and conversion of forests for agriculture.
"It is now abundantly clear that infectious disease are a great threat to the survival of primate species," he said.
Ebola has wiped out more than a quarter of the world's gorillas since 1994, while chimpanzees are suffering from respiratory virus epidemic.
Gillespie said that increased disease monitoring of wildlife could help health experts better respond to emerging pathogens, while local educational campaigns could reduce the transmission of disease between humans, livestock, and wildlife. Given that wildlife in undisturbed areas appear to be healthier than animals in logged forests, it would seem that protection of remaining forest areas could also help mitigate the risk of emerging disease.