Tuesday, August 18, 2020

USDA APHIS Confirms SARS-CoV-2 in Farmed Mink in Utah


SARS-CoV-2 - much like SARS and MERS-CoV before it - appears to have originated from bats, and then jumped - either directly, or more likely via an intermediate host - to humans. For MERS, we know the dromedary camel is an intermediate host, and for SARS, the palm civet remains the prime suspect. 

But the intermediate host for SARS-CoV-2 has yet to be determined, although pangolins and even snakes, have been suggested.  

While the virus has already established itself in humans, should SARS-CoV-2 find other suitable animal reservoirs, it could make it much harder to control, and could conceivably even provide the virus with additional evolutionary options.

Fortunately, early research has shown that the virus does not replicate well in farmed livestock, like pigs and poultry (see Susceptibility of Ferrets, Cats, Dogs & Other Domestic Animals to SARS-CoV-2) by Dr. Hualan Chen et al. 

They wrote: 
We found that SARS-CoV-2 replicates poorly in dogs, pigs, chickens, and ducks, but efficiently in ferrets and cats. We found that the virus transmits in cats via respiratory droplets. Our study provides important insights into the animal reservoirs of SARS-CoV-2 and animal management for COVID-19 control.

While we've seen scattered reports of cats (big and small), and a few dogs infected with SARS-CoV-2 (see Seroprevalence of SARS-CoV-2 in Dogs & Cats - Italy), the biggest affected non-human species to date has been farmed mink (a close relative of ferrets). 

Mink farming is big business in China, but thus far we've not heard any reports from them on SARS-CoV-2 outbreaks.  

But more than a million mink have reportedly been culled in the Netherlands after the virus spread to dozens of farms (see COVID-19 detected on multiple Dutch mink farms), and it is considered possible that one or more mink-to-human transmissions may have occurred. 

More recently, Spain ordered the culling of close to 100,000 after an outbreak at a mink farm in Teruel (see CNN Spain orders cull of nearly 100,000 farmed mink after animals test positive for Covid-19). 

And now, via the following statement issued late yesterday by USDA APHIS, we learn of the first outbreak among farmed mink in the United States. 


USDA Confirms SARS-CoV-2 in Mink in Utah
Last Modified: Aug 17, 2020
Contact: APHISpress@usda.gov

Washington, D.C., August 17, 2020 -- The United States Department of Agriculture’s (USDA) National Veterinary Services Laboratories (NVSL) today announced the first confirmed cases of SARS-CoV-2 (the virus that causes COVID-19 in humans) in mink at two farms in Utah. These are the first confirmed cases of SARS-CoV-2 in mink in the United States. The affected farms also reported positive cases of COVID-19 in people who had contact with the mink.

After unusually large numbers of mink died at the farms, the Utah Veterinary Diagnostic Laboratory completed necropsies on several of the affected animals. Samples were forwarded and tested presumptive positive for SARS-CoV-2 at the Washington Animal Disease Diagnostic Laboratory. Both laboratories are members of the National Animal Health Laboratory Network. The presumptive positive samples were then sent to NVSL for confirmatory testing.

Mink were known to be susceptible to SARS-CoV-2, as the virus was discovered in mink on multiple farms in the Netherlands. Those affected farms also experienced an increase in mink deaths. Affected mink farms have also been identified in Spain and Denmark. USDA has closely monitored these outbreaks and recently issued a document containing guidance for farmed mink in the United States.

There is currently no evidence that animals, including mink, play a significant role in spreading the virus to humans. Based on the limited information available to date, the risk of animals spreading SARS-CoV-2 to people is considered to be low. More studies are needed to understand how different species may be affected by the virus that causes COVID-19, and whether animals may play a role in the spread of the virus.

NVSL serves as an international reference laboratory and provides expertise and guidance on diagnostic techniques, as well as confirmatory testing for foreign and emerging animal diseases. Such testing is required for certain animal diseases in the U.S. in order to comply with national and international reporting procedures. The World Organisation for Animal Health (OIE) considers SARS-CoV-2 an emerging disease, and therefore USDA must report confirmed U.S. animal infections to the OIE.

USDA announces cases of confirmed SARS-CoV-2 in animals each time it is found in a new species. All confirmed cases in animals in the United States are posted at https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/sa_one_health/sars-cov-2-animals-us.

People with COVID-19 can spread the virus to animals during close contact. It is important for people with suspected or confirmed COVID-19 to avoid contact with pets and other animals to protect them from possible infection.

For more information about COVID-19 and animals and recommendations for animal owners, visit CDC’s COVID-19 and Animals page at https://www.cdc.gov/coronavirus/2019-ncov/daily-life-coping/animals.html.

While mink, and to a lesser extent cats and dogs, are susceptible to infection they are far more likely to be infected by a human (reverse zoonosis), than the other way around. 



There is currently little evidence of animal-to-human transmission of SARS-CoV-2 from companion animals,  but the CDC does maintain a web page with advice for pet owners.

Updated June 28, 2020
What you need to know
  • A small number of pets worldwide, including cats and dogs, have been reported  to be infected with the virus that causes COVID-19, mostly after close contact with people with COVID-19.
  • Based on the limited information available to date, the risk of animals spreading COVID-19 to people is considered to be low.
  • It appears that the virus that causes COVID-19 can spread from people to animals in some situations.
  • Treat pets as you would other human family members – do not let pets interact with people outside the household.
  • If a person inside the household becomes sick, isolate that person from everyone else, including pets.
  • This is a rapidly evolving situation and information will be updated as it becomes available.

What to do if you own pets
Until we learn more about how this virus affects animals, treat pets as you would other human family members to protect them from a possible infection.

Because there is a small risk that people with COVID-19 could spread the virus to animals, CDC recommends that pet owners limit their pet’s interaction with people outside their household.
  • Keep cats indoors when possible and do not let them roam freely outside.
  • Walk dogs on a leash at least 6 feet (2 meters) away from others.
  • Avoid public places where a large number of people gather.
  • Do not put face coverings on pets. Covering a pet’s face could harm them.
There is no evidence that the virus can spread to people from the skin, fur, or hair of pets. Do not wipe or bathe your pet with chemical disinfectants, alcohol, hydrogen peroxide, or any other products not approved for animal use.

Talk to your veterinarian if your pet gets sick or if you have any concerns about your pet’s health. 
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