BEACHPORT, AUSTRALIA / RankWire.AI / – Australia has identified H5N1 bird flu in a long-nosed fur seal discovered dead in Beachport, South Australia. This marks the first confirmed case of a mammal infected during the ongoing outbreak on the Australian mainland. A member of the public reported the animal on August 19 after it was found without visible injuries. Authorities gathered samples for laboratory analysis, which confirmed the presence of the virus, broadening the known range of affected species in the mainland outbreak.
Initial testing by the state was inconclusive, prompting further analysis. 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. The town is situated on South Australia’s Limestone Coast, an area where wildlife monitoring has increased amid the outbreak. Authorities have also recorded infections among various seabird species along the coast and in other affected regions.
By August 23, South Australia had reported 194 confirmed H5 events, including 11 new cases announced that day. The latest cases involved greater crested terns, a gannet, a little penguin, a silver gull, and a black-faced cormorant. Officials now classify outbreaks as events that may involve one or more animals at a specific location. Across Australia, authorities documented 298 positive H5 events by Sunday, with South Australia accounting for the majority of these confirmed detections.
H5N1 outbreak expands to mammal on the mainland
The outbreak on the mainland started in June 2026 after authorities detected H5N1 in migratory seabirds. Follow-up testing revealed the virus in native seabirds that do not migrate, including greater crested terns. In 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 recently caused infections in wild birds, poultry, and mammals across several regions outside Australia.
No reports have linked H5 bird flu infections in Australian poultry or other livestock to the current outbreak. The Australian Centre for Disease Control continues to assess the risk to the public as low. No locally acquired human cases associated with the strain circulating among wildlife have been recorded in Australia. Health officials advise avoiding direct contact with sick or dead animals and recommend reporting unusual wildlife deaths to allow testing and monitoring efforts to proceed.
Previous seal infections detected on Heard Island
Australia previously confirmed H5N1 in southern elephant seals on Heard Island, an external territory in the Southern Ocean. Those findings were announced in November 2025, several months before the virus was detected on the mainland. Further testing later identified H5 bird flu in additional wildlife on Heard Island, including Antarctic fur seals and gentoo penguins. The Beachport fur seal thus represents the first confirmed mammal infection linked to the current mainland H5N1 outbreak and the first such case in a native mainland mammal.
Authorities continue to monitor coastal wildlife as H5N1 spreads among seabirds across parts of Australia. The public is asked to maintain a safe distance from sick or deceased birds and marine mammals. Officials also encourage recording locations and reporting unusual deaths to animal health authorities. These reports support ongoing testing and help track the distribution of confirmed cases. The Beachport case adds a mammal to the expanding list of wildlife affected during Australia’s current H5N1 bird flu outbreak on the mainland.