Thirteen gorillas at Atlanta Zoo have tested positive for COVID-19, according to officials.
A fully vaccinated staff member is believed to have transmitted the virus to the gorillas, the zoo said in a statement on its website.
The zoo tested samples of the gorillas' fecal matter after they recently started showing COVID-19 symptoms.
"We are very concerned that these infections occurred, especially given that our safety protocols when working with great apes and other susceptible animal species are, and throughout the pandemic have been, extremely rigorous," Atlanta Zoo animal health director Sam Rivera said.
"The teams are very closely monitoring the affected gorillas and are hopeful they will make a complete recovery. They are receiving the best possible care, and we are prepared to provide additional supportive care should it become necessary."
All 20 of the zoo's gorillas will now undergo regular COVID-19 testing.
