Four-year-old Malay tiger Nadia was tested for the virus as a precaution after she received dry cough. Also her sister Azul and two Siberian tigers and three African lions have had similar symptoms but have not been tested for the virus.

Nadia's positive test results have been confirmed by the US Department of Agriculture, USDA.

Infected by caretakers

Probably the animals were infected by a zookeeper before this showed any signs of illness, the zoo writes in a statement.

"It is not known how this disease develops in large cats because different species react differently to new infections, but we will monitor them closely and expect them to be completely restored," the zoo writes.

The sick tigers and lions at the Bronx Zoo are said to feel good, except that they have had a somewhat reduced appetite.

The zoo has been closed since March 16, just like New York's other zoos.

Previous cases

Earlier, three pets, one cat in Belgium and two dogs in Hong Kong, were diagnosed with covid-19 after being infected by their owners. Although the infection is believed to have started in a wild animal market in Wuhan, China, there is no evidence that humans have been infected by animals since then.