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

[tetano]

Euro Surveill


. 2024 Jun;29(25).
doi: 10.2807/1560-7917.ES.2024.29.25.2400063. Highly pathogenic avian influenza A(H5N1) virus infections on fur farms connected to mass mortalities of black-headed gulls, Finland, July to October 2023

Lauri Kareinen ¹ , Niina Tammiranta ¹ , Ari Kauppinen ¹ , Bianca Zecchin ² , Ambra Pastori ² , Isabella Monne ² , Calogero Terregino ² , Edoardo Giussani ² , Riikka Kaarto ³ , Veera Karkamo ¹ , Tanja Lähteinen ¹ , Hanna Lounela ¹ , Tuija Kantala ¹ , Ilona Laamanen ¹ , Tiina Nokireki ¹ , Laura London ¹ , Otto Helve ⁴ , Sohvi Kääriäinen ⁴ , Niina Ikonen ⁴ , Jari Jalava ⁴ , Laura Kalin-Mänttäri ⁴ , Anna Katz ⁴ , Carita Savolainen-Kopra ⁴ , Erika Lindh ⁴ , Tarja Sironen ⁵ , Essi M Korhonen ⁵ , Kirsi Aaltonen ⁵ , Monica Galiano ⁶ , Alice Fusaro ² , Tuija Gadd ¹



Affiliations

• PMID: 38904109
• DOI: 10.2807/1560-7917.ES.2024.29.25.2400063

Abstract

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.

Keywords: Finland; Fur animal; Highly Pathogenic Avian Influenza A(H5N1); Mutation; black-headed gull; fox; mink; raccoon dog; silver fox.

[tetano]

Editorial

• One health, many interpretations: vaccinating risk groups against H5 avian influenza in Finland

Since 2020, highly pathogenic avian influenza (HPAI) A(H5N1) has caused widespread mortality in both wild and domestic birds in Europe and several consequent spillover events to mammals [1]. Outbreaks in fur farms in Europe and dairy cattle in North America serve as very recent examples of the unpredictable nature of the virus.

In July 2023, an HPAI A(H5N1) outbreak caused by clade 2.3.4.4b genotype BB was detected in fur farms in Finland [2]. Kareinen et al. describe in this issue of Eurosurveillance the epidemiological, pathological and genomic investigations of the outbreak [3]. Intensified surveillance activities identified 27 RT-PCR A(H5N1)-positive fur farms in western Finland. The outbreak was contained by the end of the year and affected nearly half a million farmed fur animals, mainly foxes and minks. Whole genome sequencing was carried out on outbreak viruses and shared as soon as available with the scientific community through the GISAID EpiFlu database. Phylogenetic analyses indicated several initial introductions of genotype BB clade 2.3.4.4b viruses through large-scale exposure of fur animals to infected wild birds. The genomic analyses further revealed several mutations indicative of early mammalian adaptation of the viruses in their mammalian hosts.

Animals in the affected farms were eventually culled [4]. The impact of culling 485,000 animals on a total of 72 farms was estimated by the Finnish Food Authority to have resulted in compensation for lost income of 50.7 million EUR to the owners of the affected farms [5]. The potentially relevant global health and economic consequences led to public discussion on the need to stop fur farming in Finland altogether, as was done in Denmark when during the COVID-19 pandemic farmed minks were infected by severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) [6]. Recognising the constitutional rights of the fur farmers to their livelihood [7], the Finnish government instead focused on providing extensive advice to the fur farms how to protect farmed animals from getting into contact with wild birds. The public health authorities had a major role in the outbreak management due to its possible significant public and global health impact. The epidemiological data were constantly evaluated from a human health perspective and provided the bases for recommendations for the general population, healthcare providers, and other concerned parties. Also, viral evolution was monitored by the Finnish Food Authority to assess the potential human health impact of the mutations emerging in the virus during the fur farm epidemic. Whole genome sequencing and genomic analyses revealed several mutations indicative of an early mammalian adaptation of the viruses isolated during the fur farm outbreak in Finland in 2023 [2]. As a consequence, and in addition to several nonpharmaceutical measures, vaccines were considered as a tool to prevent severe human illness, as well as to minimise the risk of reassortment between seasonal and avian influenza, an event that may result in variants with novel properties and increased transmission potential in the human population.

Already during spring 2023, when the European and global HPAI epidemic became obvious [1], the decision was made that those at increased risk for avian influenza should be offered a new adapted avian influenza vaccine as soon as one received marketing authorisation from the European Medical Agency (EMA) [8]. The rationale was the precautionary principle, i.e. to provide protection via immunisation to enable continued fur farming in Finland. The target groups were identified in collaboration with the Finnish Food Authority, Ministry of Social Affairs and Health and the Finnish Institute for Health and Welfare (THL)

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https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2024.29.25.2400383#html_fulltext

[Mary Wilson]

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

June 21, 2024, 03:01 PM

https://flutrackers.com/forum/forum/welcome-to-the-scientific-library/other-scientific-studies-including-seasonal-novel-flu/h5n1-research-studies-papers-academia/992436-highly-pathogenic-avian-influenza-a-h5n1-virus-infections-on-fur-farms-connected-to-mass-mortalities-of-black-headed-gulls-finland-july-to-october-2023-eurosurveillance