#17,606
Although the number of fur farms reportedly affected by H5N1 in Finland remains at 21, there are more than 600 farms at risk, and media reports suggest that testing may be backlogged.
After a slow start - the Finnish Food Safety Authority (Ruokavirasto) - appears to have taken the lead in the investigation and has ordered the culling of > 50,000 mink.
Finnish Food Agency Orders All Mink On H5N1 Affected Farms To Be Culled
Finland Food Authority: H5N1 Guidance For Bird Hunters
But what to do about 150,000+ exposed foxes and raccoon dogs has apparently not been determined. The concerns with high density fur farms is that it provides the virus with an ideal environment to spread from mammal to mammal.
Long chains of infection (see graphic below) can provide the virus with additional opportunities to adapt to a new host species, furthering its evolution. This is a topic we looked at in some depth 3 weeks ago in PNAS: Mink Farming Poses Risks for Future Viral Pandemics.
Today, Finland's Institute for Health and Welfare (THL) released their second press release in just 4 days on the continued risk from these infected fur farms. Last week's announcement was released in connection to a Eurosurveillance Rapid communication, and called for better biosecurity on fur farms.
Today's announcement is even more strongly worded, and appears (at least based on the translation) to be directed towards the Finnish Food Safety Agency.
THL's statement: Adaptation of the avian influenza virus to mammals must be stopped and attention must be paid to personal protection in fur farms
8.8.2023
The Finnish Institute of Health and Welfare (THL) states in its statement to the Food Agency that the circulation of the bird flu virus in farmed fur animals must be stopped in order to prevent the virus from adapting to mammals.
THL considers minks, whose respiratory receptors have similarities with human respiratory receptors, to be particularly problematic. Because of this, the mink is able to act as an intermediate host that adapts the bird flu virus to mammals and thus also to humans.
Another concern is related to humans' own influenza viruses, which can infect minks as well. If human and bird influenza viruses infect the mink at the same time, there is a chance for the genes of the viruses to mix. The occurrence of this situation at the mink farm must be prevented, as it enables the creation of a new virus strain for humans, increasing the risk of a new influenza pandemic.
Protection of mink farms from the corona virus was successful, so protecting farms from influenza is also possible. However, this requires significant improvements to improve the biosecurity of the shelters, such as bird protection and strict hygiene measures to prevent infections from humans to fur animals.
Although mink is considered to be the most problematic animal species in terms of avian influenza virus infections, there are also risks associated with bird flu epidemics in dense, large animal populations of foxes and other fur-bearing animals, that the virus becomes more adaptable to mammals.
The A(H5N1) bird flu virus is poorly contagious to humans. However, it can also cause serious, even fatal, infections in infected people. For this reason, fur farms must pay special attention to the protection of people working there or otherwise dealing with animals.
In the summer of 2023, exceptionally large mass deaths of wild birds as a result of A(H5N1) virus infection have been found in Finland. The virus has spread to fur farms in Finland, causing high morbidity and mortality in animals (foxes, blue foxes, minks and raccoons).
At the beginning of the respiratory infection season, the risk of human influenza A virus infections increases. This also applies to people in contact with minks at the shelter. If the highly pathogenic A(H5N1) 2.3.4.4b development line avian influenza virus that caused the epidemic now persists in the mink population of fur farms, the fall influenza season will cause a new risk situation. Human influenza A virus can be transmitted to kennels and minks. If human and bird influenza viruses infect the mink at the same time, there is a possibility of virus reassortment.As stated above, in laboratory conditions, such reassortment has resulted in a new combination of viruses, which is transmitted through the air as a droplet infection from one ferret to another. The occurrence of this situation at the mink farm must be prevented, as it enables the creation of a new,airborne virus strain for people, which increases the risk of an influenza pandemic significantly.
To combat this situation, all minks infected with avian influenza must be euthanized, the carcasses disposed of and the shelters cleaned. THL also considers that the biosecurity of fur farms must be significantly improved so that the risk of mink infections caused by influenza viruses (and other viruses such as SARS-CoV-2) is minimized. This requires actions, e.g. to improve bird protection and strict hygiene measures to prevent infections from humans to minks.In addition to the mink, the most important fur animals bred in Finland are the fox (Vulpes vulpes), the mink (Vulpes lagopus) and the raccoon (Nyctereutes procyonoides). Highly pathogenic A(H5) 2.3.4.4b - infections caused by the virus have been found in different parts of the world in foxes (15, 16) and raccoons (14, 17). During the current bird flu epidemic, infections have been found in domesticated foxes and raccoons in Finland (15).Regarding other fur animals, THL states the following. Although mink is considered to be the most problematic animal species in terms of avian influenza virus infections among fur-bearing animals, the bird flu epidemic in dense, large animal populations of foxes and other fur-bearing animals is also associated with risks of the virus changing to one better adapted to mammals.During the current epidemic, both PB2-E627K and PB2-T271A mutations have been found in viruses isolated from foxes, both of which are important for the ability of the virus to reproduce in mammalian cells.Just like with mink, it is not yet known for sure whether infections occur in shelters directly from one animal to another, and if there are direct infections, whether they occur through contact or through the air. THL believes that the circulation of the virus must also be stopped in the case of other fur animals and the biosecurity of the shelters must be improved in order to prevent the creation of new virus variants adapted to mammals.Finally, THL reminds us that although the highly pathogenic A(H5N1) bird flu virus is weakly contagious to humans, it can still cause serious, even fatal, infections in infected people. For this reason, special attention must be paid to the proper protection of persons who work with infected animals and have to deal with other animals, as well as those who participate in the cleaning of fur farms.
Without reading too much into these translated statements, it does appear that THL is urging a far-harder stance on the eradication of H5N1 than has the Food Safety Agency.
Stay tuned.
