Mountain gorillas and golden monkeys are sloppy eaters: When they’re done with dinner, they leave half-eaten fruits and bits of chewed leaves and bark in their wake. Now, researchers at UC Davis have discovered a way to capitalize on the primates’ poor table manners, using their chewed and discarded foods to detect potentially dangerous viruses.

The new virus detection method, which involves testing saliva samples on chewed foods, allows scientists to diagnose disease without disturbing the animals. Previously, in order to identify viruses, scientists had to anesthetize gorillas and golden monkeys and take blood samples and oral and rectal swabs. Because the procedure was so invasive, scientists only performed it when the primates were already showing signs of illness. Now, scientists have a simple, noninvasive way to identify viruses before they begin to spread.

Researchers published their findings in the American Journal of Primatology. The study explains that the new, noninvasive sampling methods are able to detect both RNA and DNA viruses. These include viruses spread by humans to mountain gorillas—an important finding, since approximately 60 percent of the mountain gorillas in the Virunga Conservation Range, where the study was conducted, have a chance to come into contact with humans because the region draws ecotourists.

According to the study, infectious diseases introduced by humans are one of the major threats facing the Virunga mountain gorillas. By studying saliva samples left on discarded foods, scientists will now be able to better diagnose illnesses in endangered mountain gorillas and golden monkeys, and take steps towards preventing the outbreak of epidemics.

"This is the first time that viruses have been detected on plants chewed by primates," researcher Tierra Smiley Evans explained. "This is a technique people can use without disturbing the primate's natural behaviors."

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