BEACHPORT, AUSTRALIA / RankWire.AI / – Australia has verified the presence of H5N1 bird flu in a long-nosed fur seal discovered deceased in Beachport, South Australia. This case marks the first confirmed mammal infection associated with the ongoing outbreak on the Australian mainland. A member of the public reported the animal on August 19, noting it showed no visible injuries. Following this, authorities collected samples for laboratory analysis. The results expanded the known range of species impacted by the mainland outbreak.
Initial testing by the state produced inconclusive results, prompting further investigation. CSIRO’s Australian Centre for Disease Preparedness later confirmed H5 bird flu in the seal. Officials clarified that they had not detected a cluster of sick or dead marine mammals in the Beachport vicinity. The town is situated along South Australia’s Limestone Coast, where wildlife surveillance efforts have intensified amid the outbreak. Authorities have also documented infections among various seabird species along the coastline and in other affected regions.
By August 23, South Australia had recorded 194 confirmed H5 events, including 11 new cases announced on that day. The latest findings 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 multiple animals at a specific site. Across Australia, authorities reported a total of 298 positive H5 events by Sunday, with South Australia accounting for the largest share of these confirmed cases.
H5N1 Outbreak Spreads to Mainland Mammals
The outbreak on the mainland began in June 2026 after authorities detected H5N1 in migratory seabirds. Subsequent testing identified the virus in native seabirds that do not migrate, such as greater crested terns. In August, South Australia reported more than 1,000 dead greater crested terns. The circulating strain in Australia is classified as H5N1 clade 2.3.4.4b. This same clade has caused infections in wild birds, poultry, and mammals in various 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 Australian Centre for Disease Control continues to consider the risk to the general public as low. Australia has also recorded no locally acquired human cases linked to the strain circulating in wildlife. Health officials recommend avoiding direct contact with sick or dead animals and advise reporting unusual wildlife deaths to enable testing and monitoring efforts.
Previous Seal Cases on Heard Island
Australia had previously confirmed H5N1 in southern elephant seals on Heard Island, an external territory in the Southern Ocean. The laboratory findings were announced in November 2025, several months before the virus appeared on the mainland. Further testing revealed H5 bird flu in additional wildlife, including Antarctic fur seals and gentoo penguins on the island. The Beachport fur seal thus becomes the first confirmed mammal case linked to Australia’s current mainland H5N1 outbreak and the first native mammal infection documented during this wave.
Monitoring of coastal wildlife continues as H5N1 spreads among seabirds across parts of Australia. The public is urged to keep their distance from sick or dead birds and marine mammals. Officials also encourage reporting locations and unusual mortality events to animal health authorities. These reports support ongoing testing efforts and assist in tracking the distribution of confirmed cases. The case in Beachport adds a mammal to the expanding list of affected wildlife species during Australia’s current H5N1 bird flu outbreak on the mainland.