Australia investigates suspected 1st mainland H5 bird flu case

Australia is investigating what could become its first mainland case of the highly pathogenic H5 bird flu strain after a migratory seabird in Western Australia tested positive for avian influenza, according to the national broadcaster ABC News.

The suspected case involves a brown skua found in Cape Le Grand National Park on the state's southern coast.

Initial tests detected the H5 strain, with further laboratory analysis underway to determine whether it is the deadly H5N1 variant that has devastated bird and mammal populations worldwide in recent years. Results are expected within days, ABC reported.

A second sick bird, identified as a giant petrel, is also being tested. Australian authorities have launched a coordinated response involving federal and state agencies and are urging the public to avoid contact with sick or dead birds.

If confirmed, the case would mark a significant milestone for Australia, which has largely remained free of H5N1 on the mainland despite the virus having spread across much of the world.

The strain was previously detected in wildlife on the country's remote sub-Antarctic Heard Island in late 2025.

Environment and agriculture officials said preparedness measures, including enhanced biosecurity, wildlife surveillance and response planning, have been strengthened in anticipation of the virus's possible arrival.

Experts warn that a mainland outbreak could pose serious risks to native bird species and other wildlife.