Highly pathogenic avian influenza virus H5N1 infection in skua and gulls in the United Kingdom, 2022

Fabian Z X Lean, Marco Falchieri, Natalia Furman, Glen Tyler, Caroline Robinson, Paul Holmes, Scott M Reid, Ashley C Banyard, Ian H Brown, Catherine Man, Alejandro Núñez

Research output: Contribution to journalReport/ Case Reportpeer-review

1 Citation (Scopus)


The reemergence of the highly pathogenic avian influenza virus (HPAIV) subtype H5N1 in the United Kingdom in 2021–2022 has caused unprecedented epizootic events in wild birds and poultry. During the summer of 2022, there was a shift in virus transmission dynamics resulting in increased HPAIV infection in seabirds, and consequently, a profound impact on seabird populations. To understand the pathological impact of HPAIV in seabirds, we evaluated the virus antigen distribution and associated pathological changes in the tissues of great skua (Stercorarius skua, n = 8), long-tailed skua (Stercorarius longicaudus, n = 1), European herring gull (Larus argentatus, n = 5), and black-headed gull (Chroicocephalus ridibundus, n = 4), which succumbed to natural infection of HPAIV during the summer of 2022. Cases were collected from Shetland, including Scatness (mainland), No Ness (mainland), Clumlie (mainland), Hermaness (island), Fair Isle (island), Noss (island), and the West Midlands, South East, and South West of England. Grossly, gizzard ulceration was observed in one great skua and pancreatic necrosis was observed in 4 herring gulls, with intralesional viral antigen detected subsequently. Microscopical analysis revealed neuro-, pneumo-, lymphoid-, and cardiomyotropism of HPAIV H5N1, with the most common virus-associated pathological changes being pancreatic and splenic necrosis. Examination of the reproductive tract of the great skua revealed HPAIV-associated oophoritis and salpingitis, and virus replication within the oviductal epithelium. The emergence of HPAIV in seabirds Stercorariidae and Laridae, particularly during summer 2022, has challenged the dogma of HPAIV dynamics, posing a significant threat to wild bird life with potential implications for the reproductive performance of seabirds of conservation importance.

Original languageEnglish
Pages (from-to)421-431
Number of pages11
JournalVeterinary Pathology
Issue number3
Early online date23 Dec 2023
Publication statusPrint publication - May 2024

Bibliographical note

Publisher Copyright:
© The Author(s) 2023.


  • highly pathogenic avian influenza virus
  • pancreatic necrosis
  • multisystemic tropism
  • H5N1
  • splenic necrosis
  • reproductive pathology
  • Charadriiformes/virology
  • Animals
  • Influenza in Birds/virology
  • Female
  • Influenza A Virus, H5N1 Subtype/pathogenicity
  • United Kingdom/epidemiology


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