A tiger at the Bronx Zoo in New York City has tested positive for the respiratory disease caused by the novel coronavirus, in the first known case of a human infecting an animal and making it sick.

A four-year-old female Malayan tiger Nadia at the Bronx Zoo has tested positive, while her sister Azul, as well as two Amur tigers and three African lions, had developed a dry cough and all are expected to fully recover, it says.

“We tested the cat [Nadia] out of an abundance of caution and will ensure any knowledge we gain about Covid-19 will contribute to the world’s continuing understanding of this novel coronavirus,” the zoo said in a statement on Sunday.

The big cats did have some decrease in appetite but “are otherwise doing well under veterinary care and are bright, alert, and interactive with their keepers”.

The virus that causes COVID-19 is believed to have spread from animals to humans, and a handful of animals have tested positive in Hong Kong.

But officials believe this is a unique case because Nadia became sick after exposure to an asymptomatic zoo employee, Paul Calle, chief veterinarian at the Bronx Zoo, told Reuters.

Nadia underwent X-rays, an ultrasound and blood tests to try to figure out what was ailing her. They decided to test for COVID-19 given the surge in cases in New York City, the epicenter of the outbreak in the United States.

The first tiger at the zoo, which has been shut since mid-March, began showing signs of illness on March 27.