As described by ProMedMail, the Dutch Agriculture Minister has provided another update on the outbreaks of SARS-CoV-2 that have affected at least 5 mink farms in the Netherlands to date (click here for the original Dutch version of the letter).

Another suspected mink-to-human transmission of SARS-CoV-2 has been identified (with potentially infections in  an additional two mink farm staff). These cases appear to be from a different farm than the first suspected mink-to-human infection. The route of transmission is presumed to be mink-to-human based on the gene sequences (and the illness in the mink preceding infection in the people). The sequence data I saw earlier seem consistent with that, but it’s hard to be 100% certain.

There’s also some more information about barn cats. On mink farms, cats would rarely have direct contact with mink (because mink would try to eat any part of a cat that was within reach), but the cats would have access to mink manure, which typically falls from wire cage flooring to the ground below. They have now identified antibodies against SARS-CoV-2 from 7/24 cats on one farm, indicating the cats were previously infection. The virus itself was also found in the samples from one cat, indicating it likely still had an active infection. Whether all 7 cats got infected from the mink (or mink manure), or whether there was subsequent cat-to-cat transmission will be pretty much impossible to figure out at this point.

While a lot still needs to be determined with these outbreaks, information to date highlights some important themes:

  • SARS-CoV-2 is predominantly a human virus but it can spill into other animals.
  • While most transmission is human-to-human, some infected animals can send the virus back to people, and infect other animals. (That shouldn’t come as a surprise, although sadly the One Health response to this virus has been pretty disappointing.)
  • Keeping infected people away from animals, as well as away from other people, is important. It’s better to prevent human-to-animal infection than to have to figure out how to deal with infected animals and worry about spread into wildlife.
  • Reducing the number and closeness of interactions, be they human-to-human, human-to-animal or animal-to-animal (within reason) and using practical precautions when distancing can’t be maintained (e.g. masks, gloves and other protective equipment when handling animals in high risk situations) are the key control measures for this virus.

The fact that there are multiple affected farms in the Netherlands but no reports elsewhere needs to be considered. It’s unlikely Dutch mink farmers are more likely to be infected or have closer contact with their mink. There’s reluctance in some countries to consider or test for infection with SARS-CoV-2 in animals, so whether this is a uniquely Dutch situation or a more common problem that’s not been diagnosed or reported elsewhere remains a question. Hopefully mink farmers everywhere are paying attention to this situation and implementing some control measures. It’s tough to use really good infection control practices in some of these facilities, considering how mink farms are managed and how many animals may need to be handled on a given day (e.g. when thousands of mink are being vaccinated), but measures to reduce human-mink contact whenever possible, use appropriate PPE, identify problems early and keep wildlife (and cats) away from mink barns are important.