BEACHPORT, AUSTRALIA / RankWire.AI / – Australia has confirmed the presence of H5N1 bird flu in a long-nosed fur seal discovered dead in Beachport, South Australia. This marks the initial confirmed infection in a mammal linked to the ongoing outbreak on mainland Australia. The public reported the animal on August 19 after it was found without any visible injuries. Following this, authorities collected samples and sent them for laboratory testing. The findings extended the known range of species impacted by the outbreak in the mainland region.
Initial testing by the state was inconclusive, prompting further examination. CSIRO’s Australian Centre for Disease Preparedness subsequently verified H5 bird flu in the seal. Officials stated that no cluster of sick or dead marine mammals had been identified around Beachport. Situated on South Australia’s Limestone Coast, the town has seen increased wildlife surveillance during the outbreak. Additionally, authorities have recorded infections among various seabird species along the coast and other affected areas.
By August 23, South Australia had documented 194 confirmed H5 events, with 11 new cases announced that day. Recent detections included greater crested terns, a gannet, a little penguin, a silver gull, and a black-faced cormorant. Authorities now consider outbreaks as events that may involve one or multiple animals at a particular site. Overall, Australia reported 298 positive H5 cases by Sunday, with South Australia accounting for the majority of confirmed detections.
H5N1 outbreak reaches mainland mammal populations
The mainland outbreak started in June 2026, following the detection of H5N1 in migratory seabirds. Subsequent testing identified the virus in native seabirds that do not migrate, such as greater crested terns. During August, South Australia reported over 1,000 dead greater crested terns. The circulating strain in Australia belongs to H5N1 clade 2.3.4.4b, which has previously infected wild birds, poultry, and mammals in several regions outside Australia during recent outbreaks.
There have been no reports of H5 bird flu infections in Australian poultry or other livestock related to the current outbreak. The Health authorities continue to assess the risk to the general population as low. No locally acquired human cases linked to this wildlife strain have been recorded in Australia. Officials advise the public to avoid direct contact with sick or dead animals and recommend reporting unusual wildlife deaths for testing and surveillance purposes.
Previous mammal infections identified on Heard Island
In November 2025, Australia confirmed H5N1 infection in southern elephant seals on Heard Island, an external territory in the Southern Ocean. These findings came several months before the virus was detected on the mainland. Further testing revealed H5 bird flu in additional wildlife on the island, including Antarctic fur seals and gentoo penguins. The Beachport fur seal thus represents the first confirmed mammal case associated with Australia’s current mainland H5N1 outbreak, as well as the first in a native mainland mammal.
Authorities are actively monitoring coastal wildlife as the H5N1 strain continues to spread among seabirds across parts of Australia. The public has been urged to keep their distance from sick or dead birds and marine mammals. They are also encouraged to document locations and report unusual deaths to animal health officials. Such reports facilitate testing and help track the distribution of confirmed cases. The Beachport case adds a mammal to the expanding list of affected wildlife species during Australia’s ongoing mainland H5N1 bird flu outbreak.