Two spotted hyenas at Denver Zoo are the first known to have Covid-19

The adult hyenas have so far exhibited mild symptoms of Covid-19. PHOTOS: DENVERZOO/TWITTER

DENVER (NYTIMES) - Two spotted hyenas at the Denver Zoo have tested positive for the coronavirus, becoming the first known cases in the world among hyenas, zoo and veterinary services officials announced last Friday (Nov 5).

The adult hyenas, 22-year-old Ngozi and 23-year-old Kibo, have so far exhibited mild symptoms of Covid-19, including "a little bit of coughing and sneezing", nasal discharge and lethargy, but they are believed to be "in good shape and improving", Mr Jake Kubie, a spokesman for the Denver Zoo, said on Saturday.

The hyenas are the latest in a number of infections confirmed among animals at the Denver Zoo, with positive test results returned for 11 lions and two tigers, which Mr Kubie said "have either fully recovered or are on their way to recovery".

Samples were collected from a variety of species at the zoo, said the announcement from the National Veterinary Services Laboratories, which is part of the United States Department of Agriculture. The samples were tested by the Colorado State University Veterinary Diagnostic Laboratory.

Coronavirus infections among animals in zoos and sanctuaries have affected several types of big cats, otters and non-human primates, according to the US Centres for Disease Control and Prevention (CDC). The risk of these animals spreading the virus to people is considered to be low, the CDC says.

Early in the pandemic, a Malayan tiger that was four years old at the time was the first tiger to test positive for the virus at New York City's Bronx Zoo. Other cases among zoo animals followed there and elsewhere.

Recently, Covid-19 infections were detected among tigers and lions at the National Zoo in Washington, where a lion was reported to have the Delta variant. Other cases include Sumatran tigers and snow leopards at a children's zoo in Lincoln, Nebraska; the world's oldest gorilla in captivity, among others at a zoo in Atlanta; and even vaccinated tigers at the San Diego Zoo.

This summer, zoo animals started receiving an experimental Covid-19 vaccine made by Zoetis, a veterinary pharmaceutical company in New Jersey.

Ngozi and Kibo, older adults in hyena years, were not vaccinated, and neither were the tigers and lions found to have been infected in Denver, but the zoo is working to prioritise its supply of the animal Covid-19 vaccine and ordering more.

"We have been able to vaccinate some of our animals, primates and great apes, because we know they are most at risk, but we haven't had the supply to vaccinate all of our other animals," Mr Kubie said.

For now, Mr Kubie said, the zoo's staff is observing infected animals for any signs of worsening health, whether they are less active or lose their appetite, to administer antiviral or anti-nausea medication if needed.

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