A(H5N5) in animals in Europe and North America
Highly pathogenic avian influenza A(H5N5), clade 2.3.4.4b, continues to circulate widely across northern Europe, North America and parts of Asia, with an expanding geographic and host range. According to the ECDC, seven EU/EEA countries detected the virus in wild birds between October 2024 and September 2025, while Iceland and Norway also reported outbreaks in domestic poultry. Spill-over into mammals has been recorded in several European countries, including foxes, lynx, mink, otters and pine martens, and Iceland has additionally reported infections in domestic cats. In North America, Canada reported multiple detections in wild birds, one poultry outbreak and cases in mammals such as bobcat, skunk, raccoon and grey seal, alongside infections in domestic cats. Since early 2025, the United States has confirmed 11 detections in wild birds.
Genomic analysis of the human case reported in Washington State on 14 November 2025 (A/Washington/2148/2025) shows that the virus belongs to clade 2.3.4.4b genotype A6, consistent with strains circulating in North American birds and mammals. Its HA segment clusters with current A(H5N5) viruses but is distinct from the A(H5N1) genotypes B3.13 and D1.1 associated with recent human infections. The Washington isolate does not contain mammalian-adaptation markers beyond those already established in avian strains.
ECDC reports that genotype EA-2021-I has circulated during the past epidemiological year in Iceland, Norway, the United Kingdom and sporadically in Belgium, the Netherlands, Finland and Germany. All European detections of this genotype in 2025 carried PB2 mutations (E627K or E627V) linked to mammalian adaptation and representing two separate clusters. Similar variants were identified in Canada in late 2024. These PB2 markers were absent from the A/Washington/2148/2025 virus sequence.
