July 2, 2024

Critical Public Health Threat: Deadly Fungus Found in Commercial Soil, Compost, and Flower Bulbs

First detected in October 2020 in Europe, the HPAI A(H5N1) clade 2.3.4.4b virus has since infected various mammal species globally. In North America, natural bird flu infections have been observed in several bear species, including Asiatic black bears, American black bears, grizzly bears, and Kodiak brown bears. Animals in captivity, such as sloth bears, Asiatic black bears, and giant pandas, have also contracted other influenza A(H1N1) viruses. Additionally, antibodies against H3 and H6 influenza subtypes suggest previous natural exposures to bird flu viruses. Notably, seroconversion has been observed in Barents Sea polar bears and Alaskan brown bears but not in southern Beaufort Sea polar bears.

Genome analysis of Alaskan wildlife influenza viruses has revealed both unreassorted and reassorted strains. The HPAI virus genotype A3 was likely introduced into Alaska via the East Asia-Australia Flyway in November 2021. Since then, it has been detected in various wild birds, including California condors in Arizona, and mammals such as red foxes, fishers, martens, raccoons, and brown bears along the Pacific Flyway.

Polar bears (Ursus maritimus) are classified as a threatened species under the US Endangered Species Act. Understanding their health threats is crucial for conservation efforts and developing effective management strategies. This study reports the case of a male polar bear naturally infected with the HPAI H5N1 virus that succumbed to the infection.