SARS-CoV-2 Outbreaks on Mink Farms

This article summarises the ongoing saga of SARS-CoV-2 (the virus that causes COVID-19) outbreaks on mink farms.

Article last updated: 17 December 2020

Photo by Nettverk for dyrs frihet (Network for Animal Freedom)

American mink are susceptible to SARS-CoV-2 infection, and there have been numerous outbreaks reported on mink farms in Canada, the United States, the Netherlands, Italy, Spain, Sweden and Denmark.(1) 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 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 fecal matter.(2) The Dutch government had originally 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.(2)(3)

Other outbreaks on mink farms have occurred in the US states of Wisconsin, Utah, and Oregon.(4)(5) 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.(3) It is important to emphasize that all of these outbreaks  on mink farms are “spill-overs” from the human pandemic, and that there’s no evidence the virus originated in American mink. Farmed mink likely contracted the virus from infected staff before spreading it amongst themselves.

Although little research has been conducted on the issue, it is unlikely that feral American mink 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 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,(6) 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.(7)

A wild American mink tested in the US state of Utah is 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.(8)

On the whole, we’re still in the early stages of understanding a complex virus. We should allow more evidence to surface before we, once again, misplace blame on the 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 create perfect breeding grounds for viruses.(9)

Virus mutation (Cluster 5)

There have been reports that the SARS-CoV-2 virus, which humans transmitted to farmed mink, has mutated in these animals in Denmark. This new variant of the virus (termed Cluster 5) was able to be passed back to humans, and has been detected in a small number of the Danish population. While currently 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 won’t work if it’s allowed to spread within the human population. To lesson fears, the Danish government attempted to pass emergency legislation to cull all of the country’s 15-17 million farmed mink,(10) but nearly a week later this plan was supposedly dropped after receiving opposition from MPs over if the cull order was legal or properly scientifically base.(11) We say supposedly, because despite this political backlash, and the claim by the Danish Health Ministry that the SARS-CoV-2 mink variation had likely died out, the mass cull order commenced.(12)

It should be noted that some scientific experts find Denmark’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.” Furthermore, 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.(13) The term “mutate” often carries negative connotations, when in actuality some mutated strains can be less transmissible or lethal, and that they’re 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 under development, the vast majority of these mutations will not.(14)

Since the Danish buried the mink in mass, shallow graves, built up gases from decomposition later caused their bodies to swell and be push out of the ground.(15) Social media went into a frenzy, with some news outlets using sensationalistic headlines such as “’Zombie’ Mink Rising”, when it’s nothing more than a case of poor burial planning.

References
  1. Migdal, Alex. 09 December 2020. CBC News. Minks at farm in B.C.’s Fraser Valley test positive for coronavirus. Accessed 09 December 2020.
  2. Enserink, Martin. Coronavirus rips through Dutch mink farms, triggering culls. (2020): 1169-1169.
  3. FOUR PAWS Australia. 31 August 2020. “The Dutch government announced to shut down the mink farming industry in the country by March 2021“. Accessed 26 October 2020.
  4. Lewis, Sophie (2020) CBS NEWS. Thousands of mink dead from COVID-19 outbreaks in Utah and Wisconsin“. Accessed 12 October 2020.
  5. Chávez, Jenn. December 2020. OPB. Mink are catching the coronavirus on farms — including one in Oregon“. Accessed 09 December 2020.
  6. Lanese, Nicoletta. Live Science. November 2020. Escaped mink could spread the coronavirus to wild animals. Accessed 02 December 2020.
  7. Centers for Disease Control and Prevention. COVID-19 Overview and Infection Prevention and Control Priorities in Non-US Healthcare Settings“. (2020). Accessed 03 December 2020.
  8. Davidson, Lee. 14 December 2020. The Salt Lake Tribune. A wild mink in Utah is the first wild animal anywhere to test positive for COVID-19, researchers say. Accessed 15 December 2020.
  9. Greger, Michael. May 2009. Factory Farms: Recipe for Disaster“. Accessed 13 October 2020.
  10. Reuters. 04 November 2020. Denmark plans to cull its mink population after coronavirus mutation spreads to humans“. Accessed 06 November 2020.
  11. Kevany, Sophie and Carstensen, Tom. The Guardian. 09 November 2020. Denmark drops plans for mass mink cull after Covid mutation fears. Accessed 09 November 2020.
  12. Kevany, Sophie and Carstensen, Tom. The Guardian. 19 November 2020. Danish Covid mink variant ‘very likely extinct’, but controversial cull continues. Accessed 26 November 2020.
  13. BRANSWELL, H. STAT. 05 November 2020. Spread of mutated coronavirus in Danish mink ‘hits all the scary buttons,’ but fears may be overblown. Accessed 09 November 2020.
  14. Ries, Julie. Healthline. 15 June 2020. COVID-19 Will Mutate — What That Means for a Vaccine. Accessed 03 December 2020.
  15. Balk, Tim. New York Daily News. 25 November 2020. Dead mink, killed over COVID concerns, resurface in Denmark. Accessed 26 November 2020.

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