ABOVE: Two of the eight gorillas currently in quarantine at the San Diego Zoo Safari Park

Three western lowland gorillas at the San Diego Zoo Safari Park have tested positive for SARS-CoV-2, the US Department of Agriculture announced yesterday (January 11), marking the first confirmed cases of the virus in great apes.

“Aside from some congestion and coughing, the gorillas are doing well,” Lisa Peterson, the executive director of the San Diego Zoo Safari Park, says in a statement. “The troop [of eight] remains quarantined together and are eating and drinking. We are hopeful for a full recovery.”

The three infected gorillas, which have runny noses and are lethargic, likely contracted the virus from an asymptomatic zoo worker, similar to the three lions and five tigers that tested positive at the Bronx Zoo in April, according to Peterson. 

Two of the gorillas...

Caretakers decided to keep all eight gorillas together and monitor them closely. “Some may have it and others may not,” Peterson, tells National Geographic. “They live in a troop with a single silverback. He’s the leader. He guides them throughout the day. They look to him. It’s really best for them that they’re allowed to continue as they are.”

Poaching and disease—namely, Ebola virus—have caused western lowland gorilla populations to decline by more than 60 percent over the last two decades, according to the World Wildlife Fund. The animals live in tight-knit family groups, so researchers worry that if the virus reaches wild populations, it may spread quickly and imperil already diminished populations.

Not including lab animals infected for experimentation, gorillas are the seventh animal species known to have contracted the virus, after lions, tigers, snow leopards, minks, dogs, and house cats. Minks are the only animals known to transmit the virus to humans.

Earlier this year, a team of scientists predicted western lowland gorillas would be at very high risk of infection, as the protein sequence for the ACE2 receptor—which SARS-CoV-2 latches onto to enter cells—is identical to our own. 

See “US Primate Centers Work to Protect Animals from COVID-19

Dan Ashe, the president of the Association of Zoos and Aquariums, tells National Geographic by email that the gorillas testing positive is “concerning,” but he has “complete confidence” that the San Diego Zoo staff is taking every precaution.

San Diego Zoo Safari Park plans to share its observations with health officials, conservationists, and scientists to help protect wild gorillas, according to the Associated Press. Primate research facilities have also taken precautions since early in the pandemic to protect their animals from transmission by human caretakers.

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