Serological Evidence of Widespread Exposure to H5 Avian Influenza Virus in Arctic Foxes in Svalbard, Norway

Abstract

The continued circulation of H5 clade 2.3.4.4b highly pathogenic avian influenza virus (HPAIV) has caused extensive mortality in wild bird populations worldwide with increasing spillover to mammals. In 2022, H5 HPAIV emerged in Svalbard, Norway, with subsequent detections in wild birds, walruses, polar bears, and arctic foxes. To understand the population-level exposure among Svalbard arctic foxes, we analysed body fluids from carcasses trapped in 2006-2015 (n = 56), 2023-2024 (n = 112), and 2024-2025 (n = 94) for antibodies to H5 avian influenza (anti-H5), influenza A nucleoprotein (anti-NP), and neuraminidase subtypes using ELISAs, haemagglutination inhibition (HI), and a multiplex assay. Only three samples from 2006-2015 tested positive for anti-H5 and were interpreted as false positives. In 2023-2024, seropositivity for anti-H5 was high (95%), supported by a lower anti-NP seropositivity (85%) and antibody profiles consistent with mixed H5N1 (42%) and H5N5 (52%) exposure. In 2024-2025, anti-H5 and anti-NP seroprevalences remained high (83% and 57%), with H5N5 (87%) exposure predominating over H5N1 (3%). A subset of anti-H5-positive samples tested positive by HI (2023-2024: 30%; 2024-2025: 14%). Juveniles with exposure limited to the previous season had higher odds of anti-H5 seropositivity in 2023-2024 than in 2024-2025 (OR 5.5). Analysis of paired lung extracts from a subset of individuals (n = 63) yielded results concordant with body fluids, using an indirect anti-H5 ELISA adapted for carnivores. Our findings demonstrate widespread H5 virus exposure. Together with occasional reports of progression to fatal HPAI, this highlights the need for continued population monitoring to evaluate ecological consequences.

Prefrontal Planning Latency Associated With Age and Serological Evidence of Microbial Exposure
Basant K. Puri, Rosemarie Preyer, Gary S. Lee +2
Chronic Diseases and Translational Medicine26 Oct 2026Peer-reviewedCC BY-NC 4.0Full textNeurosciencePMCEurope PMC
Influenza H1N1 Imprinting Uncouples Serological and B-Cell Responses in Mice
E. Tjarnhage, K. Le Quy, T. d. M. Kasahara +3
bioRxiv26 Oct 2026PreprintAll rights reservedFull textImmunologybioRxiv
Retrospective Serological Survey of Equine Influenza Virus and Piroplasm Parasites in Free-Ranging Wild Equids from Kenya and Tanzania.
Silvia Marchi, Charles Issel, Paul Kanyari +2
Veterinary sciences30 Sep 2026Peer-reviewedCC BYFull textMicrobiologyEurope PMC
Tick-borne pathogens in dogs and their ticks in France: Molecular and serological evidence from a multicenter participatory study
Djamel Tahir, Sophie Dupuis, Virginie Geolier-Lapeyronie +10
One Health3 Sep 2026Peer-reviewedCC BY 4.0Full textMicrobiologyHAL
Embryonated chicken eggs clear systemic H3N2 influenza without RIG-I: transcriptomic evidence for innate sufficiency and brain immune privilege
O. S. Gurses Sahin, J. B. Fung, D. Lehri +1
bioRxiv11 May 2026PreprintCC BYFull textImmunologybioRxiv

Cite

BibTeX RIS

BibTeX

@misc{fosse2026serological,
  title = {{Serological Evidence of Widespread Exposure to H5 Avian Influenza Virus in Arctic Foxes in Svalbard, Norway}},
  author = {J. H. H. Fosse and E. Fuglei and F. Bonfante and L. Olsen and L. Bordes and R. K. Davidson and T. Mork and I. K. Myhrvold and L. T. Engerdahl and S. Venema and K. Sturod and J. Akerstedt and O. Hungnes and M. Z. Ballmann and L. Begeman and I. H. Nymo and R. Tonnessen and B. Ytrehus},
  howpublished = {bioRxiv},
  year = {2026},
  month = sep,
  doi = {10.64898/2026.09.17.752278},
  url = {https://www.biorxiv.org/content/10.64898/2026.09.17.752278v1},
  note = {CC BY},
}

RIS

TY  - UNPB
TI  - Serological Evidence of Widespread Exposure to H5 Avian Influenza Virus in Arctic Foxes in Svalbard, Norway
AU  - J. H. H. Fosse
AU  - E. Fuglei
AU  - F. Bonfante
AU  - L. Olsen
AU  - L. Bordes
AU  - R. K. Davidson
AU  - T. Mork
AU  - I. K. Myhrvold
AU  - L. T. Engerdahl
AU  - S. Venema
AU  - K. Sturod
AU  - J. Akerstedt
AU  - O. Hungnes
AU  - M. Z. Ballmann
AU  - L. Begeman
AU  - I. H. Nymo
AU  - R. Tonnessen
AU  - B. Ytrehus
PY  - 2026
DA  - 2026/09/17
PB  - bioRxiv
DO  - 10.64898/2026.09.17.752278
UR  - https://www.biorxiv.org/content/10.64898/2026.09.17.752278v1
AB  - The continued circulation of H5 clade 2.3.4.4b highly pathogenic avian influenza virus (HPAIV) has caused extensive mortality in wild bird populations worldwide with increasing spillover to mammals. In 2022, H5 HPAIV emerged in Svalbard, Norway, with subsequent detections in wild birds, walruses, polar bears, and arctic foxes. To understand the population-level exposure among Svalbard arctic foxes, we analysed body fluids from carcasses trapped in 2006-2015 (n = 56), 2023-2024 (n = 112), and 2024-2025 (n = 94) for antibodies to H5 avian influenza (anti-H5), influenza A nucleoprotein (anti-NP), and neuraminidase subtypes using ELISAs, haemagglutination inhibition (HI), and a multiplex assay. Only three samples from 2006-2015 tested positive for anti-H5 and were interpreted as false positives. In 2023-2024, seropositivity for anti-H5 was high (95%), supported by a lower anti-NP seropositivity (85%) and antibody profiles consistent with mixed H5N1 (42%) and H5N5 (52%) exposure. In 2024-2025, anti-H5 and anti-NP seroprevalences remained high (83% and 57%), with H5N5 (87%) exposure predominating over H5N1 (3%). A subset of anti-H5-positive samples tested positive by HI (2023-2024: 30%; 2024-2025: 14%). Juveniles with exposure limited to the previous season had higher odds of anti-H5 seropositivity in 2023-2024 than in 2024-2025 (OR 5.5). Analysis of paired lung extracts from a subset of individuals (n = 63) yielded results concordant with body fluids, using an indirect anti-H5 ELISA adapted for carnivores. Our findings demonstrate widespread H5 virus exposure. Together with occasional reports of progression to fatal HPAI, this highlights the need for continued population monitoring to evaluate ecological consequences.
ER  -

Abstract

Related

Cite