Gorillas at Zoo Atlanta are being treated after initial tests showed they were positive for the coronavirus — and the zoo plans to vaccinate them once they recover.

A care team recently noticed telltale signs: Several members of the zoo’s western lowland gorilla population were coughing, had runny noses and showed minor changes in their appetites.

After nasal, oral and fecal samples were sent for testing, the zoo received presumptive positive results indicating that several gorillas had been infected by the virus that causes covid-19, the zoo said in a statement Friday.

Zoo officials said in the statement that they were waiting for confirmation of the results after samples were sent to the National Veterinary Services Laboratories in Ames, Iowa. Rachel Davis, a spokeswoman for Zoo Atlanta, said Sunday that one confirmation had been received since the Friday statement and that the delta variant was identified. Additional results from the lab are expected in the coming days.

Davis said in an email that the zoo received presumptive positive results from all four troops of gorillas and that “the assumption is that members of all four troops have been exposed, regardless of symptoms exhibited or not exhibited.” Twenty gorillas total live in the four troops. Davis added that 18 of the 20 have exhibited varying degrees of symptoms, including sneezing, nasal discharge, coughing, decreased appetite and decreased activity.

“The teams are very closely monitoring the affected gorillas and are hopeful they will make a complete recovery,” Sam Rivera, senior director of animal health at the zoo, said in the statement. “They are receiving the best possible care, and we are prepared to provide additional supportive care should it become necessary.”

The zoo is collecting samples to test its whole gorilla population and plans to regularly test the gorillas regardless of their symptoms, it said in the statement. Because the gorillas live together in proximity, it is not possible to isolate the affected population members, Rivera said, according to the Atlanta Journal-Constitution.

The gorillas “at risk of developing complications” from the virus are being treated with monoclonal antibodies, the zoo said. As they recover, the next step will be to vaccinate them with a vaccine developed for animals.

More animals across the country have been receiving vaccine doses, as zoos respond to and try to prevent coronavirus outbreaks among animal populations.

The San Diego Zoo Wildlife Alliance said in March that a group of great apes received an experimental vaccine for animals developed by veterinary pharmaceutical company Zoetis. The San Diego Zoo staff began administering doses of the vaccine after a gorilla troop there became infected. Separately, in July, a 9-year-old male snow leopard that had not yet been vaccinated tested positive for the virus.

The Oakland Zoo has started a coronavirus vaccination program for some animals using an experimental vaccine uniquely formulated for animals. (Oakland Zoo via Storyful)

The Oakland Zoo administered the Zoetis vaccine over the summer to its tigers, bears, mountain lions and ferrets in an effort to proactively protect the animals against the virus.

Zoo Atlanta said it had received the green light from the U.S. Agriculture Department and Georgia’s state veterinarian to administer the Zoetis vaccine. The zoo said in its statement that the doses had arrived, and it planned to vaccinate its Bornean and Sumatran orangutans, Sumatran tigers, African lions and clouded leopard. As the gorillas recover, Davis said, they will get vaccinated.

The Centers for Disease Control and Prevention has said that the virus has been shown to infect mammals, and there have been documented reports around the world of animals, including pets and those in zoos and sanctuaries, being infected. The agency noted that most got the virus after contact with infected humans.

It’s not certain how the gorillas became sick, but the zoo said the virus may have been passed on by a fully vaccinated team member who cares for them. The team member was asymptomatic and wearing personal protective equipment (PPE) at work, the zoo said.

The use of PPE when working with great apes was “already a standard practice at Zoo Atlanta due to their susceptibility to many of the same illnesses experienced by humans, including the common cold and influenza,” the zoo noted.

The zoo said it’s not concerned about any risk for Zoo Atlanta visitors, “given the distance between the areas used by guests and the animals’ habitats.” The CDC notes that the risk of animals spreading the coronavirus to people is considered low.

“We are very concerned that these infections occurred,” Rivera added in the statement, “especially given that our safety protocols when working with great apes and other susceptible animal species are, and throughout the pandemic have been, extremely rigorous.”

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