Thousands of minks at Utah fur farms have died because of the coronavirus in the past 10 days, forcing nine sites in three counties to quarantine, but the state veterinarian said people don’t appear to be at risk from the outbreak.

The COVID-19 infections likely were spread from workers at the mink ranches to the animals, with no sign so far that the animals are spreading it to humans, said Dr. Dean Taylor, the state veterinarian, who is investigating the outbreak.

“We genuinely don’t feel like there is much of a risk going from the mink to the people,” he said Thursday.

Between 7,000 and 8,000 minks have died since the disease swept through the ranches that produce the animals, valued for their luxurious pelts. So far, no animals in Utah have been euthanized because of the disease, and it doesn’t appear to be necessary, Taylor said.

Fur from the dead infected animals will be processed to remove any traces of the virus and then used for coats and other garments, according to Fur Commission USA, a mink farming trade group. The U.S. produces more than 3 million mink pelts each year.

Taylor declined to name the farms or the counties where the affected minks were found.

With minks, as with humans, COVID-19 is less deadly for the young.

“It’s going through the breeding colonies and wiping out the older mink and leaving the younger mink unscathed,” Taylor said. Most of the deaths have been in minks between the ages of 1 and 4 years.

In addition to the minks, more than 50 animals in the U.S. had tested positive for the coronavirus as of Sept. 2, according to the U.S. Department of Agriculture. The infections have been detected in pet cats and dogs, as well as lions and tigers at a New York zoo.

Minks seem particularly susceptible to COVID-19, likely because of a protein in their lungs, the ACE2 receptor, which binds to the virus and appears to predict vulnerability to the infection, according to Wageningen University & Research in the Netherlands. Humans also have this protein in their lungs.

The COVID outbreak in Utah has surged since mid-August, when the first cases of the disease in the animals were confirmed by the USDA.

Minks were discovered to be susceptible to the SARS-CoV-2 virus, which causes COVID-19, in April, after outbreaks at several farms in the Netherlands, followed by outbreaks in Denmark and Spain. More than 1 million animals were culled in those countries, according to the Associated Press.

Several workers at the Utah mink farms have tested positive for COVID-19, including some who had no symptoms.

“Some of our mink ranchers have more than one facility, and that’s probably how it spread,” Taylor said.

A study in the Netherlands found that the virus appeared to jump back and forth between people and minks, but the data so far remains limited.

After the initial U.S. cases were confirmed, mink farms across Utah and the rest of the country implemented strict measures to prevent the disease from spreading, such as restricting access, conducting health checks on workers and disinfecting surfaces. The USDA and the Centers for Disease Control and Prevention have issued guidelines for farmed minks and other mustelids, a family of animals that also includes weasels and badgers.

“Obviously, it’s very concerning to have a species that is this susceptible with this high of a death rate,” Taylor said.

The outbreak has led to the quarantine of a quarter of Utah’s three dozen mink ranches and raised concerns across the state, said Clayton Beckstead, regional manager for the Utah Farm Bureau and a fourth-generation mink farmer.

“We’re certainly worried, but I think everybody’s taking pretty extreme biosecurity measures,” said Beckstead, whose own farm has not been affected.

Utah is one of the nation’s top mink producers. Overall, there are 245 fur farms in 22 states, part of an industry valued at $82.6 million a year, according to Fur Commission USA.

Investigating an outbreak of a novel virus in a new species is “daunting,” Taylor said.

“We’re learning as quick as we can,” he said. “We’re scrambling to help these animals and protect this industry.”