California detects first case of COVID infection in wildlife

The COVID virus has been found in a deer in the Sierra Nevada, representing the first detection of the pathogen in California’s free-ranging wildlife.

The discovery, revealed in a new analysis of a sample from a mule deer buck collected in 2021, has no immediate consequence for people. There is already much human-to-human transmission, and vaccines largely protect us.

But the finding, announced by the California Department of Fish and Wildlife, adds to the growing concern by scientists that animals could act as a hiding place for the virus, perhaps breeding dangerous variants that cause new outbreaks in people.

“We expected that if we looked for this virus, we’d find it,” said Dr. Brandon Munk, senior wildlife veterinarian with the California Department of Fish and Wildlife. “But the bottom line is: We don’t yet know what any of it means.”

Previous research has revealed that the virus can also lurk in cats, dogs and zoo animals, as well as deer in other states.

There’s evidence, although still no proof, that an animal sold at a market in Wuhan, China, in late 2019 spread the virus to people, igniting the global pandemic.

And outbreaks in mink farms in the Netherlands have shown that infected animals can transmit the virus to humans.

A related but far more deadly virus, called Middle East Respiratory Syndrome (MERS)-CoV, lives in camels. When it jumps to humans, it has a fatality rate of 9.5% to 34.4%. By comparison, COVID’s fatality rate is 1.1%, according to the Johns Hopkins Coronavirus Resource Center.

The good news is the virus does not appear to cause illness in deer and is not considered to be a threat to the state’s estimated 445,000 mule deer, social creatures that are named for their large ears.

The virus was detected in lymph nodes taken from the neck of a dead deer in El Dorado County, hunted and on its way to be turned into venison. Lab tests found the Delta B.1.617.2 variant, which was circulating in humans at the time. The discovery was made during part of the state’s regular wildlife surveillance effort to track the spread of infectious diseases.

Test specimens were taken from 170 black-tailed and mule deer collected in 2020 and another 209 black-tailed and mule deer collected in 2021. Testing was conducted by the California Animal Health and Food Safety Laboratory at UC Davis, with confirmation provided by the U.S. Department of Agriculture’s lab in Ames, Iowa. The El Dorado deer was the only tested animal in California infected with COVID.

Results were delayed because the usual approach to sample processing had to be modified, said Monk.

In addition, wildlife veterinary labs are stretched thin by the demands of more catastrophic potential outbreaks, such as avian influenza and botulism in birds, hemorrhagic disease in rabbits or chronic wasting disease in deer and elk.

Nevertheless, COVID is beginning to show up in deer across the country with more regularity.

Wildlife officials in Utah recently announced that a November-December 2021 field study had detected the first case of SARS-CoV-2 in mule deer.