Scientists are investigating whether minks can pass on coronavirus to humans, after outbreaks at farms in Spain and the Netherlands.
It is thought that the outbreaks started with infected workers on the mink farms, passing the virus on to the small animals.
Scientists believe it is “plausible” that the minks then passed it back to the staff and are exploring how much of a danger the animals pose.
In Spain, the outbreak at a mink farm near La Puebla de Valverde infected 14 members of staff, including the owner in late May.
After operations were closed down, two more employees tested positive for COVID-19.
More than 92,000 minks were slaughtered after it was thought more than 90% of them had contracted the virus.
After the outbreak in the Netherlands, Professor Wim van der Poel, who studies animal viruses at Wageningen University and Research, said the strain of the virus in the animals was similar to the one in humans.
“We assumed it was possible that it would be transmitted back to people again,” he added.
Early in the outbreak it was assumed that oronavirus was initially transmitted from an animal, thought to be bats, but this has never been confirmed.
If it is proven that minks are able to pass on the disease to humans, it would be the first documented case of animal-human transmission.
The World Health Organisation (WHO) is aware of the outbreak on the mink farm, but believes that transmission from animals to humans was “very limited”.
Dr Maria Van Kerkhove, from the WHO, said: “This gives us some clues about which animals may be susceptible to infection and this will help us as we learn more about the potential animal reservoir of (the virus)”.
In the Netherlands, more than a million minks have already been killed across 26 farms, according to the country’s Food and Consumer Product Safety Authority.
Protocols at farms in Spain and the Netherlands have been tightened and the transportation of minks has been banned.