Science’s COVID-19 reporting is supported by the Pulitzer Center and the Heising-Simons Foundation.
COVID-19 has now struck mink farms in the United States, too. Yesterday, roughly 10 days after farmers in Utah reported a rash of mink deaths, the U.S. Department of Agriculture (USDA) confirmed the SARS-CoV-2 virus had infected the weasellike mammals, which are raised for their fur.
Infections of mink have already been documented in other countries, including Denmark, the Netherlands, and Spain. In June, authorities in these countries gassed hundreds of thousands of animals, concerned that the mink could harbor the virus indefinitely, enabling infections to persist among farm animals—and potentially spread to humans.
In Utah, the trouble started on 6 August, when farmers called the state’s Department of Agriculture and Food. At issue: “deaths in numbers they’d never seen before,” said Bradie Jones, the department’s public information officer. The wave of deaths set things into high gear, and farmers quickly sent deceased animals to Tom Baldwin, a veterinary pathologist at Utah State University, Logan, for inspection.
The initial samples were not usable, Baldwin says, because they had deteriorated by the time they arrived on 7 August. Eventually, however, some of the “great many” dead mink he received were in good enough condition to be necropsied. After cutting them open, he says he found lungs that were “wet, heavy, red, and angry,” all signs of pneumonia. That type of pneumonia is not typical in mink, he notes, but it was nearly identical to photographs of mink necropsies performed in Europe.
By 14 August, both the Washington Animal Disease Diagnostic Laboratory and USDA’s National Veterinary Services Laboratory had confirmed the animals were infected with the COVID-19 virus.
The mink cases have “big implications … and [are] worthy of everyone’s attention,” says Dean Taylor, Utah’s state veterinarian. One issue is that U.S. mink farmers will now have to be on the lookout for the virus, which can spread rapidly. (As of 30 July, 27 farms in the Netherlands had confirmed infections.) There are at least 245 mink farms in 22 states, according to Fur Commission USA, the nation’s largest association of mink farmers. More than three dozen farms operate in Utah, according to Clayton Beckstead, northeastern regional manager of the Utah Farm Bureau Federation.
“The threat to the livelihoods of those who farm the mink is very real,” Baldwin says, in large part because farms may be required to eradicate infected animals. In the Netherlands, farmers had killed more than 1 million mink as of 2 August. U.S. farms churn out more than 2.5 million pelts annually, according to USDA. Utah is the country’s second highest producer, processing more than 550,000 pelts annually.
There are still “big, unanswered question[s]” regarding “how readily this virus can move from mink into human beings,” Baldwin says. The Dutch government reported multiple cases of transmission from mink to farm staff, and several staffers on the Utah farms who came in contact with the mink have confirmed COVID-19. Researchers are now trying to determine whether these workers gave the virus to the mink, or vice versa. The two farms are under 30-day quarantines, as USDA, the Centers for Disease Control and Prevention, and state authorities investigate further.
Even a nonzero chance that the virus could mutate and amplify in mink populations—before making a jump back into humans—is worrisome, Baldwin says. “Given we’re dealing with real people with families and husbands and wives,” he says, “that’s enough for me to consider this a very serious matter.”