Information From the WVDL Regarding Mustelid Species Affected by SARS-CoV-2 –

By: Dr. Kathleen Deering, Diagnostic Pathologist / WVDL

Mink are exquisitely vulnerable to infection with SARS-CoV-2 (Sudden Acute Respiratory Syndrome Coronavirus-2).  Like humans, mink may also develop interstitial pneumonia, but the clinical disease in these animals is frequently severe and swiftly fatal.  Large outbreaks of  COVID-19 infected mink have occurred in Europe and, more recently, in several states in the U.S. Unfortunately, one of the most recent outbreaks took place on a mink farm in Wisconsin, resulting in the loss of large numbers of animals. 

The source of infection in these outbreaks in mink has been determined to be exposure to COVID-19 positive people working with these animals.  Infected mink are presumed to subsequently transmit the virus to other mink on the premises.  Infection between mink has been observed in the absence of direct contact between animals. The role of fomites and other forms of indirect transmission currently cannot be ruled out. Seropositive cats were identified on the premises of two infected mink farms in Europe; however, the source of the seropositivity and the role these cats may have played in disease transmission on these farms remain unknown. In one report, SARS-CoV-2 was not found in air samples collected outside of the facilities which housed infected mink.

Clinical signs reported in infected mink include watery to mucoid nasal discharge, dyspnea, anorexia, gastrointestinal signs, fever, and sudden death. Periocular moisture and crusting was also observed in several of the infected mink examined at WVDL.  Asymptomatic SARS-CoV-2 positive mink have been identified and reported.

While the ability of infected mink to transmit SARS-CoV-2 to humans has not been proven and is still highly speculative, wearing appropriate personal protective equipment (PPE) is advised for anyone working on the premises with potentially infected mink.

WVDL played a major role in the diagnosis of the recent mink COVID-19 outbreak in our state.  The current guidelines for mink and other mustelid species (e.g., ferrets, fishers, martens, otters, skunk, badgers) sample submission to WVDL for disease and/or cause of death investigations are:

  • RECOMMENDED SAMPLE TYPE: Nasal or Oropharyngeal swabs in BHI (brain heart infusion) broth for transport for SARS-CoV-2 PCR testing. Swabs and BHI transport media may be requested by contacting the lab.
  • Submission of tissue samples and bodies of mustelid species is not recommended from premises with ongoing outbreaks that have not ruled out SARS-CoV-2 by PCR testing of nasal oropharyngeal swabs.

Please call ahead to alert us to impending mustelid species sample submissions.  And, as always, please call to speak with us should you have any questions concerning SARS-CoV-2 in mink or related species, and for how we may assist in cases of concern.

Links of interest:

Interim SARS-CoV-2 Guidance and Recommendations for Farmed Mink and Other Mustelids:

https://www.aphis.usda.gov/animal_health/one_health/downloads/sars-cov-2-guidance-for-farmed-mink.pdf

In-depth summary of reports of naturally acquired SARS-CoV-2 infections in domestic animals and farmed or captive wildlife:

https://www.avma.org/resources-tools/animal-health-and-welfare/covid-19/depth-summary-reports-naturally-acquired-sars-cov-2-infections-domestic-animals-and-farmed-or