Humans Pass on Deadly Infections to Endangered Mountain Gorillas

On the one hand, it's pretty amazing that I can find images of a specific mountain gorilla family in Rwanda through a simple Flickr search. But the availability of those photos comes from the numerous visits of humans to the national parks in Congo, Rwanda and Uganda where the world's remaining 786 mountain gorillas live, and those visits may have a deadly downside for the gorillas: respiratory infections from human viruses.

Mountain gorillas (Gorilla berengei berengei) live only in the mountainous region where Congo, Rwanda and Uganda meet, and their small numbers make them vulnerable to extinction. To make matters worse, they are sandwiched between some of the most populous areas of Africa, and threatened by habitat destruction and poaching. A lesser known problem is infectious disease, which is the second biggest cause of death for the gorillas, after trauma, and accounts for one fifth of all sudden deaths.

And now a study in the journal Emerging Infectious Diseases documents two gorilla deaths from the human metapneumovirus (HMPV) in 2009. During that summer, the Hirwa family of gorillas in Rwanda experienced an outbreak of respiratory disease; 11 of the 12 animals experienced symptoms including coughing, nasal discharge and lethargy. Veterinarians from the Mountain Gorilla Veterinary Project treated five of the gorillas with antimicrobial drugs, but an untreated adult female and a 3-day-old male died. Analyses of the remains revealed that both individuals had been infected with HMPV, though the adult female died of a secondary bacterial pneumonia infection. The HMPV infection likely predisposed her to pneumonia, the researchers say.

"Because there are fewer than 800 living mountain gorillas, each individual is critically important to the survival of their species," said Mike Cranfield, executive director of the Mountain Gorilla Veterinary Project. "But 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."

The source of the HMPV is unknown, and the two animals that died had not been handled by any of the veterinarians or park staff during the course of their illness. But with the human population ever encroaching and tourists visiting them in their mountain homes, it seems better strategies are needed to protect the gorillas from human diseases.

Sarah Zielinski | | READ MORE

Sarah Zielinski is an award-winning science writer and editor. She is a contributing writer in science for Smithsonian.com and blogs at Wild Things, which appears on Science News.