Tuesday, August 01, 2023

Finnish Food Agency Orders All Mink On H5N1 Affected Farms To Be Culled


Not quite 3 weeks ago the Finnish Food Authority (Ruokavirasto) announced the detection of HPAI H5N1 in animals at multiple (n=5) fur farms across Southern and Central Ostrobothnia affecting blue foxes and raccoon dogs.

Over time the number of affected farms has grown to 20, with 3 of those farms raising mink as well.

As we've discussed numerous times over the years (see last January's That Touch of Mink Flu (2023 Edition), mink are particularly susceptible to COVID and Influenza A infection, raising concerns that they could act as a mixing vessel (see graphic below), possibly leading to the creation of a more dangerous virus.   


This concern was well addressed 10 days ago by two well known UK virologists in an opinion piece published in the Journal PNAS :

Thomas P. Peacock and Wendy S. Barclay 

July 19, 2023
120 (30) e2303408120

This morning, after a couple of weeks of deliberation, the Finnish Food Authority announced the decision to cull all of the mink housed at 3 H5N1 affected farms.  Decisions to cull other animals will be made on a case-by-case basis. 

According to the Finnish Fur Breeders Association, there are `. . . 581 member farms operating in Finland in approximately 600 locations, and most of them are family businesses. 95% of Finnish fur farms are located in the Ostrobothnia region'. 

The translated announcement follows. 

The Food Agency orders all minks to be culled from fur farms that have been found to be infected with bird flu

1 August 2023

The Food Agency has specified the criteria for killing fur animals infected with bird flu. Based on the decision, all minks will be killed from fur farms that have been found to be infected with bird flu. The opinion of the Norwegian Institute of Health and Welfare (THL) has also been taken into account in the policy decision regarding minks made by the Food Agency. Termination decisions regarding foxes and raccoons are still made on a case-by-case basis.

Mink is a particularly problematic animal species when it comes to avian influenza virus infections. This is because the upper respiratory tract of the mink has receptors that bind both bird and human influenza viruses, so the mink is susceptible to infections caused by both types of influenza. The mink can thus function more effectively than other mammals as an intermediate host for bird flu, where the flu virus can better transform into a form that infects humans. To prevent such viral transformations, it is important to destroy all minks from infected fur farms.

The termination of foxes and raccoons is decided on a case-by-case basis

In termination decisions concerning foxes and raccoons, the Food Agency can order all or part of the fur farm's foxes and raccoons to be culled. This decision is influenced by how widely and with how strong the symptoms of bird flu infection occur in the shelter. It is also possible that the animals in the shelter are not ordered to be euthanized at all for the time being, if the symptoms and increased mortality have stopped at the shelter. However, the restrictions imposed by the regional administrative agency on fur farms and the measures to prevent the spread of the disease remain in force at all farms where bird flu has been confirmed. If not all the animals in the infected shelters have been ordered to be euthanized, additional samples are repeatedly taken from the animals in these shelters to monitor the infection situation.

An order to kill the animals was issued to three fur farms

The Food Agency has so far issued orders to kill animals at three fur farms. The preparation of new termination orders continues this week. The Food Agency does not publish information about fur farms that have been ordered to kill animals.

Animal owners have the right to seek compensation from state funds for animals euthanized by order of the Food Agency. The amount of compensation is not yet known.

By the end of July, bird flu has been detected in twenty fur farms. The samples of the four shelters are currently being supported.

Read more about bird flu on the Food Agency's website (ruokavirasto.fi)

Following last October's large outbreak of avian flu at a European mink farm (Spain: Avian H5N1 Spillover Into Farmed Mink), new concerns have been raised over the risks of mink farming.

Last January a Eurosurveillance report on that outbreak reported evidence of a rare mammalian adaptation - (T271A), which `enhances the polymerase activity of influenza A viruses in mammalian host cells and mice' - in the virus.

That report was followed by a report from Denmark (see SSI: Low to Moderate Risk of Human Infection With Bird Flu From Mink).  While conceding that `There is limited knowledge about the occurrence and course of HPAI virus infections in mink', they wrote in their 19-page assessment:

SSI assesses that the risk of infection to humans from mink is low to moderate in the event of exposure to infected mink. This assessment is in line with assessments from ECDC and WHO.

The risk of humans becoming infected is greatest if the virus spreads between mink. Early detection of viruses in mink and humans is essential to reduce the overall health risk.

And just a month ago, in the CDC: New IRAT Risk Assessment On Mink Variant of Avian H5N1, we saw  this `mink flu' officially added to the CDC's list of zoonotic influenza viruses of greatest concern. 

While still classified as a `moderate' threat, it's scores have risen in 6 of the 10 parameters used to evaluate their zoonotic potential (see chart below)

While it is true that other animals (see H5N1 in Swine. H5N1 in cats, and H5N1 in Marine Mammals) may pose similar threats, their susceptibility to H5N1 - and their current ability to transmit it - pales in comparison to farmed mink.   

Making hard choices regarding the culling of animals sometimes a grim necessity.