A tiger at the Bronx Zoo has tested positive for coronavirus and six other tigers and lions are also thought to be suffering from the illness.
The animals are all thought to have been infected by an employee who was not yet showing symptoms, the zoo said.
The infection of the four-year-old Malayan tiger named Nadia is believed to be the first known infection in an animal in the US or a tiger anywhere, federal officials and the zoo said.
Nadia started showing symptoms on March 27 and the zoo tested her "out of an abundance of caution” and aim to “contribute to the world’s continuing understanding of this novel coronavirus,” said Dr Paul Calle, the Bronx Zoo's chief veterinarian.
The animals are all said to be doing well and are expected to recover, the zoo said.
It has been closed to the public since March 16 amid the surging coronavirus outbreak in New York.
The finding raises new questions about transmission of the virus in animals.
The US Department of Agriculture, which confirmed Nadia’s test result at its veterinary lab, said there are no known cases of the virus in US pets or livestock.
“There doesn’t appear to be, at this time, any evidence that suggests that the animals can spread the virus to people or that they can be a source of the infection in the United States,” said Dr Jane Rooney, a veterinarian and a USDA official.
The USDA said it is not recommending routine coronavirus testing of animals, in zoos or elsewhere, or of zoo employees.
But Dr Rooney said a small number of animals in the US have been tested through the USDA’s National Veterinary Services Laboratories, and all those tests came back negative except Nadia’s.
The coronavirus outbreaks around the world are driven by person-to-person transmission, experts say.
There have been reports of a small number of pets outside the United States becoming infected after close contact with contagious people, including a Hong Kong dog that tested positive for a low level of the pathogen in February and early March.
Hong Kong agriculture authorities concluded that pet dogs and cats could not pass the virus to human beings but could test positive if exposed by their owners.
Some researchers have been trying to understand the susceptibility of different animal species to the virus, and to determine how it spreads among animals, according to the Paris-based World Organisation for Animal Health.