The infection in three female cats and one male is only the second documented case of the coronavirus in big cats since four tigers and three lions tested positive in April at the Bronx Zoo in New York.

The lions, Zala, Nima and Run Run, all 16 years old, and 4-year old Kiumbe, underwent a PCR test. This is the same type of test carried out on the staff members in November after they showed mild symptoms of the disease.

In a statement, the zoo said the “lions were given veterinary care for their mild condition,” which they explained is “similar to a very mild flu condition.”

All four responded well to anti-inflammatory treatment and are being observed closely.

A statement from the zoo said the animals were no longer showing upper respiratory symptoms but still had mild coughing and sneezing.

Veterinary authorities who are investigating are optimistic there will be no widespread infections as the lions have had no contact with other animals.