Human Respiratory Disease Passes to Wild Mountain Gorillas

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Humans and gorillas share approximately 98 percent of their DNA, and now a new study confirms that they also share something else: an ability to contract the same diseases. An international team has found that a human respiratory disease can pass to wild mountain gorillas, and it has resulted in two gorilla deaths.

Wild mountain gorillas are endangered

The close genetic relationship between humans and gorillas is of interest for many reasons, one being the latter’s rapid disappearance, especially the endangered wild mountain gorilla. Fewer than 800 of these gorillas remain in the wild, living in the Virunga mountain region of Central Africa and in Uganda’s Bwindi Impenetrable National Park.

In this new study, which was conducted by researchers from Mountain Gorilla Veterinary Project; the Wildlife Health Center at the University of California, Davis; the Center for Infection and Immunity at Columbia University; and the Rwanda Development Board, it has been confirmed that a virus causing respiratory disease in humans has been transmitted to and caused the deaths of two gorillas. The fear that the 2 percent genetic difference between humans and gorillas could make the latter susceptible to human diseases seems to now be a reality.

The gorilla population has had close contact with humans for a few reasons. One is the conservation efforts being made by individuals like Dian Fossey and organizations like the Mountain Gorilla Veterinary Project. According to Mike Cranfield, executive director of the Mountain Gorilla Veterinary Project, “mountain gorillas are surrounded by people, and this discovery makes it clear that living in protected national parks is not a barrier to human diseases.”

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Gorillas are exposed to humans because the national parks are bordered by dense human populations, and also because of gorilla tourism, which brings in thousands of people every year to view the animals.

Like humans who contract viral respiratory disease, the wild mountain gorillas, when ill, experience coughing, nose and eye discharge, and fatigue. In an outbreak of respiratory disease among the gorillas in 2009, a dozen animals became sick, and two died.

When tissue samples from the dead gorillas were examined, they were found to have the biochemical signature of an RNA virus called human metapneumovirus. Veterinarians at the Mountain Gorilla Veterinary Project have noted an increase in the frequency and severity of respiratory disease cases among the mountain gorillas in recent years.

Other primates have also been studied to determine their genetic similarities to humans. A study reported in Nature in January 2011 noted that chimpanzees and humans share 99 percent of DNA, while orangutans and humans come in at 97 percent.

The authors of the study note that “although human proximity to mountain gorillas is essential for their conservation, also crucial is minimizing the risk for human-to-great ape transmission of respiratory pathogens.” Monitoring is critical to ensure the survival of these endangered animals.

SOURCES:
Locke DP et al. Nature 2011; 469 (7331): 529 doi: 10.1038/nature09687
Palacios G et al. Emerging Infectious Diseases 2011 Apr; 17(4); doi: 10.3201/eid1704.100883

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