BEACHPORT, AUSTRALIA / RankWire.AI / – Australia has officially identified H5N1 avian influenza in a long-nosed fur seal found deceased in Beachport, South Australia. This marks the first confirmed case of mammal infection linked to the ongoing outbreak on the mainland. A citizen reported the animal on August 19, noting no visible injuries. Authorities collected samples for laboratory analysis, which expanded the known range of affected species during this outbreak.
Initial testing conducted by the state returned inconclusive results, prompting further investigation. CSIRO’s Australian Centre for Disease Preparedness later verified the presence of H5 bird flu in the seal. Officials emphasized that no cluster of ill or dead marine mammals had been identified around Beachport. Situated on South Australia’s Limestone Coast, the town has seen increased wildlife monitoring amid the outbreak. Reports of infections in various seabird species along the coast and other affected regions have also been documented.
As of August 23, South Australia had confirmed 194 H5 events, including 11 new cases announced on that day. The recent detections involved greater crested terns, a gannet, a little penguin, a silver gull, and a black-faced cormorant. Authorities now record outbreaks as incidents that may involve one or multiple animals at a specific site. Across Australia, a total of 298 positive H5 events had been reported by Sunday, with South Australia accounting for the largest share of those confirmed cases.
Expansion of H5N1 to Mainland Mammals
The outbreak on the mainland commenced in June 2026 after authorities detected H5N1 in migratory seabirds. Subsequent testing revealed the virus in native seabirds that do not migrate, including greater crested terns. During August, South Australia reported over 1,000 dead greater crested terns. The strain circulating in Australia belongs to H5N1 clade 2.3.4.4b, which has caused infections in wild birds, poultry, and mammals in several regions outside Australia during recent outbreaks.
The current outbreak has not been linked to infections in Australian poultry or other livestock. The Australian Centre for Disease Control continues to assess the risk to the public as low. There have been no reports of locally acquired human cases associated with this strain circulating among wildlife. Health officials recommend avoiding direct contact with sick or dead animals and advise the public to report unusual wildlife deaths for testing and monitoring purposes.
Previous Seal Cases Were Detected on Heard Island
Earlier, Australia confirmed H5N1 in southern elephant seals on Heard Island, an external territory in the Southern Ocean. In November 2025, authorities announced those laboratory findings, several months prior to the virus’s appearance on the mainland. Follow-up testing identified H5 bird flu in additional wildlife species on the island, including Antarctic fur seals and gentoo penguins. The Beachport fur seal thus represents the first confirmed mammal infection tied to Australia’s current mainland H5N1 outbreak and the first detection of such in a native mainland mammal.
Monitoring of coastal wildlife continues as H5N1 spreads among seabirds in parts of Australia. The public is urged to keep their distance from sick or deceased birds and marine mammals. Officials also encourage recording locations and reporting unusual mortality events to animal health authorities. These reports facilitate testing and help track the distribution of confirmed cases. The Beachport seal adds to the list of affected wildlife species during Australia’s ongoing H5N1 bird flu outbreak on the mainland.