The Current

With a COVID-19 infection confirmed in tigers, researchers hope to learn more about its spread among animals

With a confirmed case of COVID-19 found in a tiger at the Bronx Zoo in New York City, researchers hope to shed light on how the novel coronavirus jumped from wild animals to humans.

Discovery opens up the conversation about other species that may be susceptible, epidemiologist says

A Sumatran tiger is seen in its pen at the Toronto Zoo in Toronto, Thursday Sept. 21, 2006. On Monday, a tiger tested positive for COVID-19 at the Bronx Zoo in New York City. (Adrian Wyld/The Canadian Press)

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With the first confirmed case of COVID-19 in a non-domestic animal, researchers hope to shed light on how the novel coronavirus jumped from wild animals to humans.

Nadia, a four-year-old tiger at the Bronx Zoo in New York City, was confirmed to have been infected with COVID-19, along with six other big cats on Monday. 

"We know that it [the novel coronavirus] likely started in bats, but we don't actually know how it was transmitted to humans and what animal did that," said Natasha Daly, a reporter for National Geographic.

"The fact now that we know that big cats are able to contract the virus will obviously be really important information going forward in studying how this can transmit and spread."

Experts believe the seven cats contracted the illness from an asymptomatic zoo employee. The animals first started showing symptoms on March 27, and the diagnosis was confirmed by a nasal swab.

Because any test on animals requires anesthesia, out of an abundance of caution only Nadia was tested.

Nadia the tiger tests positive for the coronavirus

3 years ago
Duration 0:45
A Malayan tiger at the Bronx Zoo has tested positive for the coronavirus; officials believe she was infected by a zoo employee.

While no other animals at the park are showing symptoms, park officials are monitoring them, Daly told The Current's Matt Galloway.

Epidemiologist Dr. John Epstein says he's not surprised that captive tigers are susceptible to COVID-19, and that the data can be helpful to broader wildlife populations.

"It opens up the conversation about other species and in particular, wildlife that may be susceptible to this virus," said Epstein, a veterinarian and disease ecologist with the EcoHealth Alliance.

Concern for great apes

Thomas Gillespie is closely watching the transmission of COVID-19 to wildlife. The Emory University professor worries about how it could impact great apes, an endangered species, living in captivity.

"We have a history of apes being very susceptible to human respiratory disease. Even viruses that tend to cause the common cold in humans have ended up causing mortality events in wild apes," he said.

No cases have been found among great apes, however Gillespie believes that the population is likely susceptible. Thanks to genome research, it's already known that great apes share the same receptor for the novel coronavirus as humans, he said. 

Researchers worry about the effect that COVID-19 could have on the planet's endangered great apes. (Felipe Dana/The Associated Press)

COVID-19 is spread through close contact with carriers, or by touching an infected surface. That means wild great apes are likely safe from the disease.

"The majority of wild apes are fearful of humans and will move away when people are near. But the ones that are habituated — the ones that we have gotten used to our presence for tourism, for research — they're the ones we're most concerned about," he explained.

Because there is no confirmed treatment or cure for the novel coronavirus infection, where possible even animals should practice physical distancing. For great apes in captivity at zoos or in research facilities, extra precautions must be taken, said Gillespie.

"Suspending research, suspending tourism, all of this is the key," he said, adding that any spaces where humans and great apes coexist should be adequately sanitized.

Researchers are already working on a COVID-19 test that uses fecal matter instead of a nasal swab to detect whether an animal is carrying the disease.

Such a test would reduce the risk associated with anesthesia.

Future disease 'reservoirs'

As scientists seek to determine whether another animal was the intermediary carrier from bats to humans, Epstein worries about the possibility of other animal "reservoirs" among wildlife, where infectious disease can live, grow and multiply.

Bats, for example, act as reservoirs for the virus that causes SARS. Given the opportunity, that virus may jump from the animal to another host when they make contact.

"Throughout history there have been animal viruses that have established themselves as human viruses," he explained. 

"When viruses make the jump, if they can be transmitted effectively from person to person, or animal to animal, they can continue to survive and exist within that species."

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Newly quiet spaces allow wildlife to gently probe boundaries in cities around the world.

While every virus is unique, and will therefore spread differently, Epstein explains that coronaviruses — the one that causes COVID-19 in particular — can be "promiscuous and have the ability to infect multiple different species."

"The question now is are there wildlife populations, are there certain animals that might be able to receive this virus from people?"

Given much is still unknown about the coronavirus and its ability to spread among wildlife, Epstein says it's important to get that research underway.

Written by Jason Vermes. Produced by Ben Jamieson and Mehek Mazhar.

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