ABBOTSFORD, B.C. — A COVID-19 outbreak at a British Columbia mink farm likely spread from eight workers to some of the animals, says the province's chief veterinarian.

Test results from five mink samples taken from a farm in Fraser Valley have come back positive for the virus that causes COVID-19 in humans, Rayna Gunvaldsen said Wednesday. 

The animal samples were gathered after workers at the farm, which has about 15,000 mink, tested positive for COVID-19 recently, she said.

Gunvaldsen said the farm was placed under quarantine, prohibiting the movement of animals and materials from the property. The quarantine order was made to prevent the spread of the virus, she said.

She wouldn't say if the animals would be culled. 

Gunvaldsen said it's likely the workers infected the mink with the virus.

"Because the mink are isolated on the property and given that there was an outbreak in the workers on the farm and the close contact that they would have with the mink in order to care for them, it's almost certain that the workers would have transmitted the virus to the mink," she said in an interview.

B.C. has 10 mink farms, all located in the Lower Mainland, said Gunvaldsen.

The Ministry of Agriculture said Wednesday in a news release the COVID-19 results for the mink were expected, "considering the interaction between infected workers and mink on the farm."

Testing was underway to determine genome sequencing and the strain of the virus at the farm, the ministry said.

Provincial health officer Dr. Bonnie Henry said they are watching for the test results from the farm because researchers have been concerned about the mutation of COVID-19 at a mink farm in Denmark.

"We are doing what we call whole genome sequencing on the sequences both from the mink that have tested positive but also on the humans to see if there's been any change in the virus that might have any effect on the spike protein, and therefore potentially have effect on the vaccine," she said at a news conference.

A plan is in place to feed and care for the mink during the outbreak, which was declared on Monday when eight workers tested positive for COVID-19, the ministry statement said.

"The plan respects the conditions of the quarantine and maintains worker and mink safety," the ministry statement said. "The outbreak at this farm is not considered to pose a health risk to other mink farms."

Denmark, the world's largest supplier of mink fur, decided last month to cull all of its farmed mink, about 15 million animals.

Spain culled about 100,000 farmed mink, and in the U.S., about 10,000 mink in Utah died as the virus spread across farms.

The World Health Organization said in a statement on Dec. 3 that the decision to cull mink in Denmark was made following information that revealed it wasn't possible to stop the spread of infection from farm to farm, or from animals to humans.

"Mink are acting like a reservoir and contributing to the ongoing transmission in Denmark," the WHO said.

Mink farming in Denmark has now been banned until the end of December 2021.

The B.C. farm was inspected by the chief veterinarian and ministry staff as part of a routine inspection process in September and was found to comply with all animal welfare and biosecurity standards, the ministry statement says. 

The ministry said samples were submitted to the Canadian Food Inspection Agency's National Centre for Foreign Animal Disease in Winnipeg and the World Organisation for Animal Health has been notified. 

— By Dirk Meissner in Victoria.

This report by The Canadian Press was first published Dec. 9, 2020. 

The Canadian Press