Australia loses its H5N1 bird flu shield as deadly strain arrives via migratory seabirds

Australia confirmed highly pathogenic H5N1 clade 2.3.4.4b—the strain that's ravaged wild birds globally—in two locations: a seabird near Esperance in Western Australia and Heard Island in November 2025. The detections suggest ongoing transmission from migratory flyways rather than a contained outbreak. Public health risk remains low, but the $3.5 billion poultry industry faces immediate biosecurity pressure as agencies activate response protocols.