BEACHPORT, AUSTRALIA / RankWire.AI / – Australia has identified H5N1 avian influenza in a long-nosed fur seal discovered dead in Beachport, South Australia. This marks the initial confirmed case of a mammal infection linked to the ongoing outbreak across mainland Australia. The animal was reported by a member of the public on August 19 after it was found without visible injuries. Authorities collected samples for laboratory testing, which confirmed the virus’s presence and expanded the known range of species impacted by the outbreak on the mainland.
Initial testing by the state produced an inconclusive result, prompting further analysis. CSIRO’s Australian Centre for Disease Preparedness later verified H5 bird flu in the seal. Officials stated that there was no evidence of a cluster of sick or dead marine mammals around Beachport. Located on South Australia’s Limestone Coast, Beachport has seen intensified wildlife surveillance during the outbreak. Additionally, authorities have documented infections among multiple 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 most recent detections involved greater crested terns, a gannet, a little penguin, a silver gull, and a black-faced cormorant. Officials now categorize outbreaks as events that may include one or multiple animals at a specific location. Across Australia, the total confirmed positive H5 cases reached 298 by Sunday, with South Australia accounting for the largest share of these detections.
H5N1 outbreak extends to mainland mammals
The outbreak on the mainland began in June 2026 following the detection of H5N1 in migratory seabirds. Subsequent testing found 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, a lineage that has infected wild birds, poultry, and mammals in several 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 population as low. To date, no locally acquired human cases linked to the strain circulating in wildlife have been recorded in Australia. Health officials recommend avoiding direct contact with sick or dead animals and advise reporting unusual wildlife deaths to authorities to facilitate testing and monitoring.
Previous seal cases occurred on Heard Island
Australia 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 was detected on the mainland. Additional testing later identified H5 bird flu in more wildlife on the island, including Antarctic fur seals and gentoo penguins. The Beachport fur seal therefore represents the first confirmed mammal infection associated with 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 has been advised to maintain distance from sick or dead birds and marine mammals. Officials also encourage reporting locations and unusual deaths to animal health authorities. These reports assist with testing efforts and tracking the distribution of confirmed cases. The Beachport incident adds a mammal to the growing list of wildlife species affected during Australia’s ongoing mainland H5N1 bird flu outbreak.