Highly pathogenic avian influenza A (H5N1) virus

Highly pathogenic avian influenza (HPAI) H5N1 virus is spread globally by wild birdsThe circulating H5N1 clade (2.3.4.4b) has caused outbreaks on poultry farms and among backyard flocks, and die-offs among wild birds.Infections in mammals, including cattle and humans, triggered by viral spillover from birds highlights the potential for a pandemic, but the mechanisms of transmission are not fully known. 1,2Evidence exists of viral reassortment and mammalian adaptation, 3 resulting in increased risk of transmission and disease among mammals.