By Raphaela Stimmelmayr et al.
Source CDC
Since its emergence in Europe during October 2020, highly pathogenic avian influenza (HPAI) A(H5N1) clade 2.3.4.4b virus has frequently spilled over into diverse mammal hosts globally. In North America, natural H5N1 infections have occurred in several bear species, including American black bears (Ursus americanus), Asiatic black bears (U. thibetanus), grizzly bears (U. arctos horribilis), and Kodiak brown bears (U. a. middendorffi) (1). Infections with influenza A(H1N1) viruses have been reported in captive sloth bears (Melursus ursinus) and Asiatic black bears (2,3) and in giant pandas (Ailuropoda melanoleuca) (4). Detection of hemagglutination inhibition antibodies against H3 and H6 subtype influenza viruses also suggested previous natural exposure to influenza viruses of avian origin (4). Seroconversion after natural exposure to bird influenza viruses has been documented in the Barent Sea polar bear subpopulation (2010–2011) (5) and brown bears in Alaska (2013–2016) (6) but not in the southern Beaufort Sea polar bear subpopulation (2013–2016) (7). Polar bears are a threatened species under the US Endangered Species Act. We report and describe an infection by HPAI H5N1 virus in a free-ranging polar bear found dead in Alaska, USA, during 2023.
Read more https://wwwnc.cdc.gov/eid/article/30/8/24-0481_article