Australia confirms first H5N1 bird flu case on sub-Antarctic Macquarie Island

Australia confirmed on 17 October 2026 its first case of H5N1 avian influenza, detected in elephant seals on sub-Antarctic Macquarie Island. The UNESCO World Heritage-listed territory sits in the Southern Ocean roughly halfway between Tasmania and Antarctica and is a vital breeding ground for southern elephant seals, penguins and seabirds. Officials said samples from sick and dead animals tested positive for the highly pathogenic H5N1 strain, which is believed to have reached the island via subantarctic migratory bird populations crossing the Indian Ocean. The detection is a milestone in the global H5N1 outbreak that began in 2020: Australia and New Zealand had been the last major landmasses untouched, and with Macquarie's confirmation the virus has now been recorded on or near every continent. Scientists warned that the island's dense colonies of wildlife, with little immunity, could suffer significant mortality, as seen in South American and Antarctic elephant seal rookeries over the past two years. Australian biosecurity authorities said surveillance, carcass sampling and strict access rules for researchers would be scaled up, and urged commercial poultry producers on the mainland to reinforce farm biosecurity to limit any onward spread to domestic flocks.