At least 13 western lowland gorillas from the Atlanta zoo are being treated after testing positive for COVID-19, according to zoo officials.

“Recently, Gorilla Care Team members observed coughing, nasal discharge, and minor changes in appetite in several members of the gorilla population,” the zoo said in a statement. “Fecal samples and nasal and oral swab samples were sent to the Athens Veterinary Diagnostic Laboratory at the University of Georgia, where they tested presumptively positive.”