BEACHPORT, AUSTRALIA / RankWire.AI / – Australia has verified H5N1 bird flu infection in a long-nosed fur seal discovered dead in Beachport, South Australia. This marks the first confirmed case of mammal infection linked to the ongoing outbreak on mainland Australia. The animal was reported by a member of the public on August 19 after being found without visible injuries. Authorities collected samples from the carcass and submitted them for laboratory testing, which revealed the virus’s presence and expanded the known range of affected species during this mainland outbreak.
Initial testing conducted by state officials yielded inconclusive results, prompting additional analysis. CSIRO’s Australian Centre for Disease Preparedness later confirmed that the seal was infected with H5 bird flu. Officials clarified that no cluster of sick or dead marine mammals had been identified around Beachport. Situated on South Australia’s Limestone Coast, Beachport has seen increased wildlife surveillance amid the outbreak, with authorities also documenting 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. The latest detections involved greater crested terns, a gannet, a little penguin, a silver gull, and a black-faced cormorant. The authorities now define outbreaks as events that may involve one or multiple animals at a specific location. Across Australia, a total of 298 positive H5 events had been reported by Sunday, with South Australia accounting for the largest share of these confirmed cases.
H5N1 outbreak extends to mainland mammal
The outbreak on the mainland began in June 2026, following the detection of H5N1 in migratory seabirds. Subsequent testing identified the virus in native seabirds that do not migrate, including greater crested terns. During 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, a lineage that has affected wild birds, poultry, and mammals in various regions outside Australia during recent outbreaks.
So far, authorities have not reported H5 bird flu infections in Australian poultry or other livestock associated with the current outbreak. The Australian Centre for Disease Control continues to evaluate the public health risk as low. There have been no locally acquired human cases linked to the strain circulating in wildlife. Health officials advise the public to avoid direct contact with sick or dead animals and urge reporting unusual wildlife deaths to allow testing and monitoring efforts to be carried out.
Previous seal infections recorded on Heard Island
Australia had previously confirmed H5N1 in southern elephant seals on Heard Island, an external territory in the Southern Ocean. These findings were announced in November 2025, several months before the virus was identified on mainland Australia. Follow-up testing also detected H5 bird flu in other wildlife on the island, including Antarctic fur seals and gentoo penguins. Consequently, the Beachport fur seal represents the first confirmed mammal infection associated with Australia’s current mainland H5N1 outbreak and the first instance of a native mammal affected on the mainland.
Authorities continue to monitor coastal wildlife as the H5N1 virus spreads among seabirds in various parts of Australia. The public is advised to maintain distance from sick or dead birds and marine mammals. Officials also encourage reporting unusual deaths and locations to animal health authorities, supporting testing efforts and tracking the spread of confirmed cases. The incident involving the Beachport fur seal adds a mammalian case to the growing list of wildlife species impacted during Australia’s ongoing mainland H5N1 bird flu outbreak.