A lion infected with SARS-CoV-2 at an Indiana zoo likely transmitted the virus to at least two of the keepers caring for the big cat, a new study has found. This is the first confirmed case of an infected zoo animal transmitting the coronavirus to a human, researchers say. However, such transmission is likely rare, and in this case likely resulted from the lion having to be hand-fed, the scientists wrote in the study.
It has long been known that SARS-CoV-2, the virus that causes COVID-19, can infect many species and can pass between humans and animals. The virus likely jumped from an animal to a human in the first place, and previous studies have suggested that pet cats and dogs catch SARS-CoV-2 from owners at extremely high rates. Other studies have shown that deer transmitted the virus to humansand infected hamsters at a Hong Kong pet store triggered a human outbreak of the delta variant.
However, “animal-to-human transmission of SARS-CoV-2 has not yet been reported in a zoo,” the researchers wrote in the paper, which was published Jan. 31 in the SARS-CoV-2 database. preprint. medRxiv (opens in a new tab). (The results have not yet been peer-reviewed.)
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The Unidentified African lion (panthera leo), who was around 20 years old and resided at the Potawatomi Zoo in South Bend, tested positive for SARS-CoV-2 in December 2021 after developing a cough and becoming short of breath. The 10 caretakers who had been in close contact with the infected feline were immediately tested and all tests came back negative. But later in the week, three of the guardians tested positive, having not been in contact with any other infected humans.
In the new study, the researchers genetically sequenced viral samples taken from the infected lion and zookeepers. The results showed that the lion and two of the guardians shared a genetically identical strain of the virus, but the sample from the third guardian could not be correctly sequenced.
The lion was elderly – wild lions very rarely grow past their mid-teens – and suffered from kidney disease and spinal degeneration, which meant he had to be hand-fed. This greatly increased the chances of the keepers contracting lion disease before he showed symptoms. After the lion tested positive, keepers wore respirators when interacting with the lion and all other zoo animals.
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Researchers suspect the lion contracted SARS-CoV-2 from an asymptomatic zookeeper. The lion had received two doses of a non-human COVID-19 vaccine in September and October 2021.
COVID-19 is particularly dangerous for felines, which share the same receptors for the virus as humans, which means they can become extremely ill or even die from the disease, new scientist (opens in a new tab) reported. The lion was euthanized several days after testing positive, due to the severity of its symptoms.
Zoo animals and COVID-19
A wide variety of zoo animals have been infected with SARS-CoV-2, including gorillas, snow leopards, hippos, hyenas and giraffes. The first zoo animal in the United States known to be infected with COVID-19 was a tiger at the Bronx Zoo in New York back in April 2021.
However, the risk of most humans contracting the virus from an animal remains very low and humans are much more likely to infect animals than the other way around, according to the Centers for Disaster Control and Prevention (opens in a new tab).
“You would have to be in very close contact with such animals to be infected,” study co-author Leslie Boyer (opens in a new tab), the medical director of the University of Arizona’s Venom Immunochemistry, Pharmacology and Emergency Response (VIPER) Institute, told New Scientist. “People love vets, farmers [and] zookeepers who often work near the mouth and nasal regions of these animals are most at risk of such transmission. »