A four-year-old Malayan tiger named Nadia confirmed to have contracted COVID-19 by the USDA's National Veterinary Services Laboratory.
This is believed to be the first known case of an animal infected by a human with COVID-19.
Three other tigers, including Nadia's sister Azul, and three lions developed coughs and are expected to recover.
The cats started showing symptoms, including a dry cough, late last month after exposure to the employee, who has not been identified.
"This is the first time that any of us know of anywhere in the world that a person infected the animal and the animal got sick," Paul Calle, the chief veterinarian at the zoo, told Reuters news agency on Sunday.