HPAI H5N1 Infections on Finnish fur farms linked to gull mortalities, July-Oct 2023
From July to October 2023, Finland experienced an outbreak of highly pathogenic avian influenza (HPAI) H5N1 on fur farms. Finland is a major producer of furs, rearing 1.5–2 million animals annually. Of these, half are foxes, 41% are minks, 9% are raccoon dogs, and less than 0.1% are sables. Most farms breed more than one species, and according to the Central Database for Animal Keepers and Establishments maintained by the FFA, there are approximately 450 fur animal holdings. A new study published in Eurosurveillance analyzed the outbreak to identify the source(s) of the infection and possible transmission routes. The HPAI H5N1 virus was detected on 27 fur farms and was found to belong to the genotype circulating in wild birds in the same area. This suggests that the outbreak was likely caused by direct contact with infected wild birds, followed by virus transmission within and between farms, as indicated by genomic and epidemiological data. The virus spread efficiently among the farmed animals, creating many opportunities for spillover to humans. The danger from fur farming practices is highlighted by observations of genetic changes during the outbreak associated with mammalian adaptation, which may increase the pandemic potential of the circulating avian influenza viruses.