The tiger, a 4-year-old female Malayan tiger named Nadia, developed a dry cough and a decrease in appetite. She was tested out of an abundance of caution, and the results were confirmed by the USDA's National Veterinary Services Laboratory in Iowa, the society said.
Her sister Azul, two Amur tigers and three African lions also showed coronavirus symptoms, but all of the cats, including Nadia, are expected to recover.
None of the zoo's snow leopards, cheetahs, clouded leopard, Amur leopard, puma or serval are showing any signs of illness.
The zoo said the cats were infected by a person caring for them who was asymptomatically infected with the virus or before that person developed symptoms.
"We were surprised, of course, because this is the first time a person has naturally infected an animal and an animal has gotten sick," said Bronx Zoo Chief Veterinarian Dr. Paul Calle.
Preventive measures are now in place for all staff who are caring for them, and the other cats in the four WCS zoos, to prevent further exposure of any other zoo cats.
The Bronx Zoo released a statement after many were concerned that Nadia could get tested while many humans cannot:
"The COVID-19 testing that was performed on our Malayan tiger Nadia was performed in a veterinary school laboratory and is not the same test as is used for people. You cannot send human samples to the veterinary laboratory, and you cannot send animal tests to the human laboratories, so there is no competition for testing between these very different situations."
Dr. Ann Hohenhaus with NYC's Animal Medical Center said it is possible for the virus to be transmitted to humans through pets -- but so far only cats.
"We know that pet cats have almost the identical virus receptor on their cells that lets the virus in that people do," Hohenhaus said.
Hohenhaus says there is no evidence of transmission through dogs, but because it is a rapidly developing situation, proper hygiene practices should still be practiced.
Nadia and Azul became visitor favorites after their appearance on Animal Planet's 2017 docu-series "The Zoo."
The Bronx Zoo has been temporarily closed since March 16.
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