Avian flu spreads to 21 fur farms, poses public health risk

The infection of avian influenza has spread to different areas in the country created a risk to public health, said the Finnish Institute for Health and Welfare (THL) in a press release on Friday.

Avian influenza viruses mutate easily and mammalian adaptation could increase their pathogenicity in humans as well.

"The risk is particularly high with minks due to similarities between the respiratory tracts of minks and humans. Minks can also become infected with seasonal influenza by humans, which increases the risk of new viral variants to emerge", said Erika Lindh, Senior Specialist of THL.

"The matter has wider than only national significance. International health authorities and scientists also recognise the worst-case scenario of mammalian adaptation leading to a pandemic caused by an influenza virus that is new to humans," said Otto Helve, Director of THL.

According to current data, avian influenza has spread to 21 fur farms in Finland. The first results from whole-genome sequencing indicate wild birds, particularly the black-headed gull, to be the source of infection.

This is reflected in the "rapid communication" article published in the Eurosurveillance journal by the Finnish Institute for Health and Welfare (THL) and the Finnish Food Authority. The article describes the avian influenza epidemic currently ongoing in fur farms in the Central and South Ostrobothnia regions of Finland.

“In the case of the more widespread infections at individual farms, the possibility of intra-farm infections cannot be ruled out. Current conditions on fur farms that do not have effective measures in place to protect the animals from birds enable the spread of viruses from wild birds to farmed animals. Risk management would require measures from fur farms to prevent birds from coming into contact with fur animals," said Terhi Laaksonen, Director of Finnish Food Authority.

Based on genetic investigations, some of the viruses found in fur animals had mutations which indicate that the virus has adapted as a result of mammalian infections. Viruses bearing mutations that enhance the replication of the virus in mammalian cells were found on two farms.

The Finnish Food Authority on August 1, ordered to cull all minks at fur farms with diagnosed avian influenza infections.

On July 25, the authority earmarked more areas as avian influenza infected zone following expansion of the infection of the disease to the new regions.

Earlier, the authority on July 21 established an infected zone to prevent further spread of the disease.