At least 18 of the 20 gorillas at the Atlanta Zoo have now tested positive for COVID-19, an outbreak that began just days before the zoo hoped to obtain a veterinary vaccine for the primates, officials said on Tuesday.
The Atlanta Zoo announced the first positive tests among western lowland gorillas on Friday after employees noticed the gorillas were coughing, runny noses and showed changes in appetite. A University of Georgia veterinary lab returned positive tests for the respiratory disease.
The Atlanta Zoo said National Veterinary Services Laboratories in Ames, Iowa, confirmed that at least four of the gorilla samples have so far tested positive for the delta variant of the virus.
The zoo says it uses monoclonal antibodies to treat gorillas who are at risk of developing complications from the virus.
Officials say there is no evidence gorillas can transmit the virus to humans and that visitors are too far away to be infected by gorillas.
Because gorillas live together in four troops, zoo officials say it’s impossible to keep infected animals in isolation.
Zoo officials say they believe an asymptomatic worker who cares for the gorillas transmitted the virus. The employee had been fully vaccinated and was wearing protective equipment such as a mask and gloves.
“According to our guidelines for animal care staff, if they have any symptoms of a cold, they should stay home,” said Dr. Sam Rivera, senior director of animal health at the zoo.
“As it turns out, the animal care team member the next day developed signs she suspected to be compatible with COVID and was tested and was positive.”
The Atlanta Zoo’s senior director of animal health, Sam Rivera, said the zoo will vaccinate gorillas with a veterinary vaccine for which it was on the waiting list before positive gorilla tests.
Eight gorillas at the San Diego Zoo Safari Park were treated for the virus in January. A silverback from San Diego received an experimental regimen of antibodies and all recovered.