Influenza A Virus in Mink

Sheep can suffer from a degenerative disease called scrapie and is caused by so-called prions in the brain. We all know what happened in the past when Bovine Spongiform Encephalopathy (BSE or ‘mad cow disease’) suddenly swept through British cattle because farmers unknowingly fed fodder to their cattle that included protein from infected sheep. Then people started to exhibit symptoms of rapidly advancing dementia. The diseased came to be known as variant Creutzfeldt-Jacob Disease (vCJD) and its cause was linked to consuming prion-infected meat that wasn’t heated thoroughly enough.

So, you might think that we have learned from this ‘mishap’ and have decided to properly heat any meat that is fed to other animals. Well, we didn’t.

Influenza in mink is considered rare. Some scattered reports[1] from Scandinavia suggested that disease in farmed mink can be the result of an Influenza A(H10N4) virus of avian origin. The most probable cause of these sporadic outbreaks were migrating birds.

Then mink on a mink farm in the US started to exhibit persistent severe respiratory distress and nose and/or mouth bleeding. Many mink died. Investigations into the exact cause of the disease showed an infection with Influenza A(H1N2) virus, which contained the matrix gene of swine lineage[2].

The most plausible way of transmission of the influenza is from the raw untreated pig waste containing lungs used in the production of mink feed. Because untreated fodder is cheaper that treated fodder, we now run the risk of creating yet another mixing vessel for the Influenza virus.

[1] Chriél et al: Consequences of outbreaks of influenza A virus in farmed mink (Neovison vison) in Denmark in 2009 and 2010 in Proceedings of the Xth International Scientific Congress in Fur Animal Production. Wageningen (the Netherlands) - 2012 
[2] Yoon et al: Naturally occurring influenza A virus subtype H1N2 infection in a Midwest United States mink (Mustela vison) ranch in Journal of Veterinary Diagnostic Investigations – 2012