The Francis Crick Institute
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Highly pathogenic avian influenza A(H5N1) virus infections on fur farms connected to mass mortalities of black-headed gulls, Finland, July to October 2023.

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journal contribution
posted on 2024-06-24, 10:45 authored by Lauri Kareinen, Niina Tammiranta, Ari Kauppinen, Bianca Zecchin, Ambra Pastori, Isabella Monne, Calogero Terregino, Edoardo Giussani, Riikka Kaarto, Veera Karkamo, Tanja Lähteinen, Hanna Lounela, Tuija Kantala, Ilona Laamanen, Tiina Nokireki, Laura London, Otto Helve, Sohvi Kääriäinen, Niina Ikonen, Jari Jalava, Laura Kalin-Mänttäri, Anna Katz, Carita Savolainen-Kopra, Erika Lindh, Tarja Sironen, Essi M Korhonen, Kirsi Aaltonen, Monica Galiano, Alice Fusaro, Tuija Gadd
Highly pathogenic avian influenza (HPAI) has caused widespread mortality in both wild and domestic birds in Europe 2020-2023. In July 2023, HPAI A(H5N1) was detected on 27 fur farms in Finland. In total, infections in silver and blue foxes, American minks and raccoon dogs were confirmed by RT-PCR. The pathological findings in the animals include widespread inflammatory lesions in the lungs, brain and liver, indicating efficient systemic dissemination of the virus. Phylogenetic analysis of Finnish A(H5N1) strains from fur animals and wild birds has identified three clusters (Finland I-III), and molecular analyses revealed emergence of mutations known to facilitate viral adaptation to mammals in the PB2 and NA proteins. Findings of avian influenza in fur animals were spatially and temporally connected with mass mortalities in wild birds. The mechanisms of virus transmission within and between farms have not been conclusively identified, but several different routes relating to limited biosecurity on the farms are implicated. The outbreak was managed in close collaboration between animal and human health authorities to mitigate and monitor the impact for both animal and human health.


Crick (Grant ID: CC1114, Grant title: McCauley CC1114)