Research and analysis

HAIRS risk assessment: avian influenza A(H5N1) in non-avian UK species

Qualitative assessment of the risk of avian influenza A(H5N1) infections in non-avian UK species present to the UK public.

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Since October 2021, avian influenza A(H5N1) clade 2.3.4.4b has become the dominant avian influenza subtype detected in wild and captive birds across Europe and the UK.

Globally, there has been an increased spillover to non-avian species including wild terrestrial and marine mammals. Positive detections of avian influenza A(H5N1) have been identified in a range of animals, mostly from the Carnivora family. In the UK, and as of March 2023, retrospective testing of samples collected since 2021 revealed positive detections in red foxes, Eurasian otters, common and grey seals, harbour porpoises and common dolphins. These were the first detections of avian influenza A(H5N1) in non-avian UK wildlife.

Although these findings appear sporadic and isolated incidents, potential mammal to mammal transmission has recently been described in farmed mink in Spain, with genetic analysis revealing an uncommon mutation (T271A) in the PB2 gene which may enhance viral activity in mammalian host cells.

To date, there are no reported transmission events of avian influenza A(H5N1) from non-avian infected species to humans. This assessment was carried out to determine the level of risk to the UK human population.

Updates to this page

Published 2 June 2023
Last updated 27 July 2023 + show all updates
  1. Updated to include new detections of avian influenza A(H5N1) in humans in the UK, and domestic animals in Europe.

  2. First published.

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