July 01, 2020

The U.S. Department of Agriculture has mobilized its national network of veterinary diagnostic laboratories to assist the nation with its SARS-CoV-2 testing needs.

As of early May, the USDA National Veterinary Services Laboratory had confirmed infections with the COVID-19 virus in four animals, all in New York state: a tiger and lion at the Bronx Zoo and two pet cats. All the animals recovered, said Dr. Mia Kim Torchetti, director of the NVSL Diagnostic Virology Laboratory. In late May, the NVSL stated it was unable to verify infection in a Pug in North Carolina.

Dr. Torchetti was speaking during a May 6 Zoonoses and One Health Update phone call with representatives of the Centers for Disease Control and Prevention, U.S. Public Health Service, and USDA.

She highlighted the preparedness of the National Animal Health Laboratory Network, which comprises 60 laboratories in 42 states. Twenty-seven of the facilities are capable of testing for SARS-CoV-2 in animals. Of those, seven are certified to also test human samples for the virus.

“Together, these labs have the capacity to provide more than 12,000 PCR (polymerase chain reaction) tests within 24 hours,” Dr. Torchetti said.

Since the May 6 phone call, the U.S. Department of Health and Human Services certified an eighth veterinary laboratory for SARS-CoV-2 testing in human samples. The Texas A&M Veterinary Medical Diagnostic Laboratory in Amarillo announced on May 27 it had been approved to conduct such testing by the HHS’s Clinical Laboratory Improvements Amendment program.

While routine testing of animals for SARS-CoV-2 is not recommended by the USDA, CDC, or AVMA, approximately 150 animals had been tested at laboratories in the laboratory network, Dr. Torchetti explained.

Roughly 80% of tested animals were dogs, cats, and ferrets, Dr. Torchetti said, and most were thought to be infected with the virus. Those that weren’t showing signs of infection were associated with a person confirmed or suspected to have COVID-19.

Other animal species have been tested. “Recently published research shows that nonhuman primates, cats, ferrets, and gold hamsters can be experimentally infected with COVID-19 and spread the infection to animals of the same species in laboratory settings,” said Dr. Casey Barton Behravesh, director of the CDC One Health Office and lead for the agency’s COVID-19 One Health Working Group, speaking on the Zoonoses and One Health Update call.

“Of note, pigs, chickens, and a duck did not become infected, based on the results of these studies.”

Dr. Behravesh explained that the findings come from a small number of animals and don’t indicate whether the animals can spread the infection to people.

There’s no evidence that SARS-CoV-2 is present in U.S. wildlife, including bats, she said. Also, it isn’t clear whether the new coronavirus would sicken North American bat species.

“It appears that the virus that causes COVID-19 can spread from people to animals in some situations,” Dr. Behravesh said. “At this time, there is no evidence animals play a significant role in spreading SARS-CoV-2.

“Based on limited information available to date, the risk of animals spreading the virus to people is considered low.”