If there is anything the COVID-19 pandemic has taught us, it is that misinformation on social media and irresponsible headlines from news outlets can cause unnecessary fear, anxiety, and confusion. This article summarises the saga of SARS-CoV-2 (the virus that causes COVID-19) outbreaks on mink farms.

Article last updated: 1 January, 2022

Like many other domestic and captive wild animals,^(1)(2)(3) North American minks can be susceptible to SARS-CoV-2 infection. In 2020, there were numerous outbreaks reported on mink farms in Canada, the United States, the Netherlands, Italy, Spain, Sweden, and Denmark.⁽⁴⁾

Europe

The Netherlands was one of the first countries to report an outbreak, where more mink were dying than usual, with some showing symptoms of nasal discharge or difficulty breathing. Tens of thousands of farmed mink in the country were gassed with carbon monoxide over fears of mink-to-human transmission. It is believed the virus may have spread amongst the mink via droplets, on feed or bedding, or in dust containing faecal matter.⁽⁵⁾

The Dutch government had initially scheduled to ban mink farming in the country by 2024, but due to the mink’s susceptibility to SARS-CoV-2 and possibility of mink-to-human transmission, this deadline was moved forward to March of 2021.⁽⁵⁾⁽⁶⁾

North America

Other outbreaks on mink farms have occurred in the US states of Wisconsin, Utah, and Oregon.⁽⁷⁾⁽⁸⁾ It has been reported that the virus tends to burn itself out at every farm once more than 90% of the mink have contracted the virus and developed antibodies.⁽⁶⁾ It is important to emphasize that all of these outbreaks on mink farms are spill-overs from the human pandemic, and that there is no evidence the virus originated in North American minks. Farmed mink likely contracted the virus from infected staff before spreading it amongst themselves.

A wild North American mink tested in the US state of Utah was the first known free-ranging, native wild animal to test positive for Covid-19; further raising concerns and calls to end mink farming. The virus strain detected was the same as the strain found in captive mink on a nearby infected mink farm. Domestic mink frequently escape from fur farms, but it is unclear how this wild mink became infected. Currently, there is no evidence suggesting that SARS-CoV-2 is being passed from mink to mink in the wild near infected mink farms.⁽⁹⁾

In late 2020, a mink-to-human transmission event occurred in the U.S. state of Michigan, in which four humans became infected. The US Centers for Disease Control (CDC) did not announce this until March of 2021. This was deemed ancestral to the Ontario WTD calde “spillover” event from white-tailed deer nearly a year later in Canada.^(10)(11)(12)

Epizootic concerns

Although little research has been conducted on the issue, it is unlikely that feral North American minks will spread the virus in the wild. Unlike mink on fur farms which are kept in close quarters and can come into contact with infected mink or humans, both feral and especially wild mink are territorial and primarily solitary animals and tend to only interact when breeding. There is a concern that feral cats and other susceptible animals could eat infected mink or come into contact with their feces,⁽¹³⁾ but it is unclear how contagious these exposures would be in a non-artificial environment, since the coronavirus’ primary mode of transmission is via respiratory droplets.⁽¹⁴⁾

We should allow more evidence to surface before we misplace blame on the North American mink. Although there is currently no evidence linking SARS-CoV-2 to an intermediate animal reservoir, keeping large groups of animals in industrial farming have in the past created perfect breeding grounds for viruses in other species.⁽¹⁵⁾

Cluster 5 / ΔFVI-Spike mutation

There were reports that the SARS-CoV-2 virus—which humans transmitted to farmed mink—had mutated in these animals in Denmark. This new variant of the virus (termed Cluster 5) was able to be passed back to humans, and was detected in a small number of the Danish population. While not found to be more severe than other strains of the virus, the Danish government believed this variant could be less sensitive to antibodies, and pose a risk that future vaccines will not work if it was allowed to spread within the human population.

To lessen fears, the Danish government passed emergency legislation in November 2020 to cull all of the country’s roughly 17 million farmed mink.⁽¹⁶⁾ Nearly a week later this plan was supposedly dropped after receiving opposition from MPs over if the cull order was legal or properly scientifically based.⁽¹⁷⁾ Despite the political backlash and the claim by the Danish State Serum Institute (SSI) that Cluster 5, in all probability, had become extinct, the mass cull order commenced.^(18)(19) This government-mandate became known as the Danish mink cull, or more commonly known as the Mink Case (Danish: Minksagen) or the Mink Scandal (Minkskandalen).

Some scientific experts found the Danish government’s claim that the mutation could undermine vaccination efforts to be a bold statement. According to molecular epidemiologist Emma Hodcroft, “It’s almost never the case that it’s such a simple story of one mutation and all your vaccines stop working”. Further, Francois Balloux, the director of University College London’s Genetics Institute, stated that the virus is not likely to increase transmission nor should it be more severe.⁽²⁰⁾ The term mutate often carries negative connotations, but some mutated strains can actually be weaker than earlier versions of the virus, so they are not necessarily always worse. Viruses mutate frequently during their life cycle, and while it is possible a new strain could reduce the effect of COVID-19 vaccines currently in circulation, the vast majority will not.⁽²¹⁾

Mass burials in Denmark

Since Denmark buried millions of mink in mass, shallow graves, built up gases from decomposition later caused their bodies to swell and be push out of the ground.⁽²²⁾ Social media went into a frenzy, with some news outlets using sensationalistic headlines such as “Zombie Mink Rising”, when it was merely a case of poor burial planning.

Several months later, Denmark’s environmental protection agency raised concern over pollution caused by the mass burials. The main pollutants found at some of the burial sites were ammonia and an excess of nitrogen. The government agency stated that there was no risk of drinking water becoming contaminated. Once the risk of contagion from the killed mink lowers, Denmark plans to unearth the carcasses and incinerate them instead.⁽²³⁾

Proposal to ban mink fur farms in the United States

A bipartisan proposal in the U.S. House of Representatives aims to ban the sale, purchase, import, and export of mink in the United States over cruelty concerns, and to prevent possible future mutations of the coronavirus.^(24)(25)

References

Back to the North American Mink’s Overview