BEACHPORT, AUSTRALIA / RankWire.AI / – Australia has verified the presence of H5N1 bird flu 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 the Australian mainland. The animal was reported by a member of the public on August 19, who found it without any visible injuries. Samples were collected by authorities and sent for laboratory analysis, which revealed an expanded range of affected species during the outbreak.
Initial tests conducted by the state yielded inconclusive results, prompting additional testing. CSIRO’s Australian Centre for Disease Preparedness subsequently confirmed H5 bird flu in the seal. Officials noted that there has been no evidence of a cluster of sick or dead marine mammals in the Beachport area. The town is situated on South Australia’s Limestone Coast, where wildlife monitoring efforts have been heightened amid the outbreak. Authorities have also documented infections in several seabird species along the coast and 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. These outbreak records are now considered to include single or multiple animals at specific locations. Across Australia, a total of 298 positive H5 events had been reported by Sunday, with South Australia accounting for the largest proportion of these confirmed cases.
H5N1 outbreak extends into mainland mammals
The outbreak on the mainland commenced in June 2026 following the detection of H5N1 in migratory seabirds. Subsequent testing identified the virus in native seabird species that do not migrate, including 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, which has also 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 evaluate the risk to the general public as low. Additionally, Australia has not recorded any 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 for testing and monitoring purposes.
Previous seal infections identified on Heard Island
In earlier cases, Australia confirmed H5N1 presence in southern elephant seals on Heard Island, an Australian external territory in the Southern Ocean. These laboratory findings were announced in November 2025, several months prior to the virus reaching mainland Australia. Further testing later identified H5 bird flu in additional wildlife on the island, including Antarctic fur seals and gentoo penguins. The Beachport fur seal thus stands as the first verified mammal infection associated with Australia’s current mainland H5N1 outbreak and marks the first such detection in a native mammal on the continent.
Authorities continue to monitor coastal wildlife populations as H5N1 spreads among seabirds across parts of Australia. The public has been urged to maintain distance from sick or deceased birds and marine mammals. Officials also encourage reporting of unusual deaths and locations to animal health authorities, supporting testing efforts and tracking the distribution of confirmed cases. The Beachport case adds a mammalian host to the growing list of affected wildlife species during Australia’s ongoing mainland H5N1 bird flu outbreak.