BEACHPORT, AUSTRALIA / RankWire.AI / – Australia has verified the presence of H5N1 bird flu in a long-nosed fur seal found deceased in Beachport, South Australia. This marks the initial confirmed case of mammal infection linked to the ongoing outbreak on Australia’s mainland. A member of the community reported the animal on August 19, observing it without any visible injuries. Authorities collected samples from the carcass and sent them for laboratory analysis. The findings broaden the understanding of species affected by the outbreak across the mainland.
Initial testing conducted by state officials yielded inconclusive results, prompting further investigation. CSIRO’s Australian Centre for Disease Preparedness subsequently confirmed H5 bird flu in the seal. Authorities also noted that no clusters of sick or dead marine mammals had been identified around Beachport. Located on South Australia’s Limestone Coast, the town has seen an increase in wildlife surveillance amid the outbreak. In addition, officials have documented infections among several seabird species along the coast and in other affected regions.
By August 23, South Australia had recorded 194 confirmed H5 events, including 11 new cases announced that day. Recent detections involved greater crested terns, a gannet, a little penguin, a silver gull, and a black-faced cormorant. Authorities now classify outbreaks as events that may include one or multiple animals at a particular site. Throughout Australia, reports indicated 298 positive H5 detections by Sunday, with South Australia accounting for the largest proportion of these confirmed cases.
H5N1 outbreak expands to include mainland mammals
The outbreak on the mainland was first detected in June 2026 after authorities found H5N1 in migratory seabirds. Further testing revealed 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, the same clade responsible for recent outbreaks involving wild birds, poultry, and mammals in various regions outside Australia.
There have been no reports of H5 bird flu infections in Australian poultry or other livestock linked to the ongoing outbreak. The Australian Centre for Disease Control continues to consider the risk to the public as low. So far, no locally acquired human cases associated with the current wildlife strain have been documented. Health authorities advise individuals to avoid direct contact with sick or dead animals and to report unusual wildlife deaths for testing and monitoring purposes.
Previous H5N1 infections identified in seals on Heard Island
Australia previously confirmed H5N1 in southern elephant seals on Heard Island, an Australian external territory situated in the Southern Ocean. The laboratory findings were announced in November 2025, several months before the virus was detected on the mainland. Later investigations identified H5 bird flu in additional wildlife on the island, including Antarctic fur seals and gentoo penguins. The Beachport fur seal case thus represents the first confirmed mammal infection related to Australia’s current mainland H5N1 outbreak and the first detection in a native mainland mammal.
Authorities continue to monitor coastal wildlife as H5N1 spreads among seabirds across parts of Australia. The public is encouraged to keep their distance from sick or deceased birds and marine mammals. Officials also urge recording locations and reporting abnormal deaths to animal health authorities, supporting testing efforts and mapping the spread of confirmed cases. The Beachport case adds a mammalian species to the list of wildlife affected during Australia’s ongoing mainland H5N1 bird flu outbreak.