The Finnish Food Authority is ordering all foxes and raccoon dogs to be culled at fur farms with diagnosed avian influenza infections. All mink at infected farms were ordered to be culled earlier. The culling order is based on protecting human health.
The avian influenza viruses isolated from infected fur animals have been sequenced, which allows examining the genome of the virus and changes to it. The results of the sequencing support the suspicion that the virus also has spread between the fur animals and not only from birds to the fur animals. In addition to droplet transmission, the virus can spread between animals through contact with the secreta (saliva in particular) or feed of the animals, or contaminated litter and animal care equipment. It is often impossible to reliably determine the route of transmission.
The longer the virus can circulate in other mammals, the higher risk of the virus mutating into a strain that can infect humans. Worrying mutations that make it easier for the virus to transfer between mammals have been found in the genome of the strains isolated from the animals of six fur farms. These mutations have been found in mink, foxes and raccoon dogs. Studies on the virus strains at fur farms continue in collaboration with the European Union Reference Laboratory for Avian Influenza.
The symptoms of animals infected with the avian influenza vary from mild to severe, and the infection can also be asymptomatic. It is therefore important that fur farms with no symptomatic animals are also subjected to inspections. For fur farms with a detected infection, sufficiently proving that the infection is eradicated would require such a large number of samples that it is not possible in practice. Hidden infections of asymptomatic animals would also cause a risk to the occupational health of employees during pelting, and the risk of spillover to humans would continue after pelting season as well.
The new termination decisions issued by the Finnish Food Authority apply to approximately 115,000 animals, of which 109,000 are foxes and 6,000 raccoon dogs. In addition, the Finnish Food Authority previously issued the culling order of some 135,000 animals, of which 50,000 were mink, 79,000 foxes and 6,000 raccoon dogs. So far, avian influenza infections have been found at 26 fur farms in Ostrobothnia. Of these, all animals in 11 farms and some of the animals in five farms have been ordered to be culled. In addition, 10 farms have not been subjected to a culling order. The current culling order applies to all the remaining animals at these farms.
Previously, termination decisions concerning foxes and raccoon dogs were made on a case-by-case basis. The scale and the severity of the symptoms of the infected farm animals were considered when making the decisions.
Terhi Laaksonen, Director, tel. +358 29 520 4530 (Animal Health and Medication)
Research Professor Tuija Gadd, tel. +358 29 520 4183 (virological studies)
Zoonoses on Finnish fur farms – risk profile (pdf)
More information on the risk to human health of avian influenza (Finnish Institute for Health and Welfare, in Finnish and Swedish only)
Instructions of the Finnish Institute of Occupational Health on protection against an avian influenza infection (in Finnish and Swedish only)