BEACHPORT, AUSTRALIA / RankWire.AI / – Australia has identified 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 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 analysis, which confirmed the presence of the virus, expanding the known range of affected species during this outbreak.
Initial testing by the state yielded an inconclusive result, prompting further investigation. CSIRO’s Australian Centre for Disease Preparedness subsequently verified H5 bird flu in the seal. Officials clarified that no cluster of sick or dead marine mammals has been observed around Beachport. Situated on South Australia’s Limestone Coast, the town has seen intensified wildlife surveillance during the outbreak. In addition, authorities have documented infections among several seabird species along the coast and other affected regions.
As of August 23, South Australia had recorded 194 confirmed H5 events, with 11 new cases announced that day. Recent detections included 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 particular location. Across Australia, authorities reported a total of 298 positive H5 events by Sunday, with South Australia accounting for the majority of those confirmed cases.
H5N1 Outbreak Extends to Mainland Mammal
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, 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 infected 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 this current outbreak. The Australian Centre for Disease Control continues to assess the risk to the general population as low. No locally acquired human cases linked to the strain circulating in wildlife have been documented in Australia. Health officials recommend avoiding direct contact with sick or dead animals and advise reporting unusual wildlife deaths to authorities for testing and monitoring purposes.
Previous Seal Infections Detected on Heard Island
H5N1 was previously confirmed in southern elephant seals on Heard Island, an Australian external territory located in the Southern Ocean. The laboratory findings were announced in November 2025, several months before the virus was identified on mainland Australia. Follow-up testing revealed H5 bird flu in additional wildlife, including Antarctic fur seals and gentoo penguins. The Beachport fur seal thus represents the first confirmed mammal infection associated with Australia’s current H5N1 outbreak on the mainland, and the first detection in a native terrestrial mammal.
Authorities continue to monitor coastal wildlife as H5N1 spreads among seabirds across parts of Australia. The public is advised to maintain distance from sick or deceased birds and marine mammals. Officials also encourage documenting locations and reporting unusual deaths to animal health authorities, aiding in testing efforts and tracking the distribution of confirmed cases. The Beachport case adds a mammal to the list of wildlife affected during Australia’s ongoing H5N1 bird flu outbreak on the mainland.