Is great ape tourism to blame for killing off chimps?

Viruses that only cause common colds in humans are devastating populations of chimpanzees and gorillas

- Rachel Nuwer

There was something wrong with the chimpanzees. For weeks, a community of 205 animals in Uganda's Kibale national park had been coughing, sneezing and looking miserable. But no one could say for sure what ailed them, even as the animals began to die.

Necropsies can help to identify a cause of death, but normally the bodies of chimps are found long after decomposition has set in. So when Tony Goldberg, a US wildlife epidemiologist visiting Kibale, got word that an adult female named Stella had been found dead, he drove straight to the park.

As the necropsy progressed, Goldberg began to see signs of a familiar disease: fluid buildup in the chest cavity and around her heart; lung tissue that was dark red, consolidated and marked with lesions. It looked like the chimp had died of severe pneumonia.

Months later, molecular testing revealed it was human metapneumovirus (HMPV), one of a collection of viruses that presents in humans as a common cold but is "a well-known killer" in our closest primate relatives, said Goldberg, a researcher at the University of Wisconsin-Madison.

More than 12% of the community that Stella belonged to died in the outbreak. Others were lost as a result of being orphaned.

This phenomenon of animals catching diseases from humans, called reverse zoonoses, affects species around the world from mussels contaminated with hepatitis A virus to tuberculosis transmitted to Asian elephants. But because of their evolutionary closeness to humans, great apes tend to be most vulnerable.

For some great ape populations that live in protected areas, reverse zoonoses are a bigger threat than habitat loss or poaching. In a group at Kibale, for example, respiratory pathogens such as human rhinovirus Cand HMPV have been the leading chimp killers for more than 35 years, accounting for 59% of deaths from a known cause.