Three lions and four tigers tested positive for Covid-19 at a zoo in New York City on Wednesday, CNN reported. With this, eight animals at Bronx Zoo have contracted the infection.

The Wildlife Conservation Society, which runs the famous Bronx Zoo in New York, told CNN that three tigers and three African lions began showing symptoms of Covid-19 in early April, when the zoo announced that a 4-year-old tiger had tested positive. Zoo authorities said that six big cats had developed a cough. One more tiger who tested positive, however, had shown no symptom.

The zoo authorities told CNN that the cats were infected by a staff member who was positive but at the time showed no symptoms. All four zoos run by the Wildlife Conservation Society in the state of New York have been closed since mid-March.

Earlier this month, a four-year-old Malayan tiger at the Bronx Zoo, named Nadia, had tested positive for the coronavirus. Nadia, her sister Azul, two Amur tigers, and three African lions had developed a dry cough. Subsequently, they were tested for Covid-19, and Nadia was found positive.

After the tiger was found to be infected, the Central Zoo Authority in India had sounded a red alert for all zoological parks and told them to collect testing samples of animals on a fortnightly basis.

In New York, the state worst-hit by Covid-19 in the United States, two cats have become the first pets in the country to contract the infection, AFP reported on Wednesday. The cats live in separate areas of New York state. More than 15,000 people have been killed by Covid-19 in New York state.

Follow live updates on the coronavirus pandemic