BEACHPORT, AUSTRALIA / RankWire.AI / – Australia has confirmed the presence of H5N1 bird flu in a long-nosed fur seal discovered dead in Beachport, South Australia. This marks the initial confirmed case of a mammal infected during the ongoing outbreak on the mainland. The animal was reported by a member of the public on August 19, who noted it showed no visible injuries. Authorities then collected samples for laboratory testing, which broadened the known range of affected species in the current outbreak.
Initial tests conducted by state officials yielded inconclusive results, 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 deceased marine mammals has been identified around Beachport. The town, located on South Australia’s Limestone Coast, has seen increased wildlife surveillance amid the outbreak. Authorities have also documented infections among various seabird species along the coast and in other affected regions.
As of August 23, South Australia had recorded 194 confirmed H5 events, with 11 new cases announced that day. Recent detections include greater crested terns, a gannet, a little penguin, a silver gull, and a black-faced cormorant. The authorities now categorize outbreaks as events, which can involve one or multiple animals at a particular site. Across the country, Australia had reported 298 positive H5 events by Sunday, with South Australia accounting for the largest proportion of these confirmed cases.
H5N1 Outbreak Extends to Mainland Mammal
The outbreak on the mainland started in June 2026 following the detection of H5N1 in migratory seabirds. Subsequent testing identified 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 strain circulating in Australia belongs to H5N1 clade 2.3.4.4b, the same clade responsible for recent outbreaks affecting 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 related to this outbreak. The Australian Centre for Disease Control continues to assess the risk to the public as low. No locally acquired human cases linked to the strain circulating in wildlife have been documented in Australia. Health officials advise the public to avoid direct contact with sick or dead animals and recommend reporting unusual wildlife deaths for testing and monitoring purposes.
Seal Cases Previously Detected on Heard Island
Australia 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 prior to the virus reaching the mainland. Additional testing later identified 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 detection in a native mainland mammal.
Authorities continue to monitor coastal wildlife as H5N1 spreads among seabirds in parts of Australia. The public has been urged to maintain distance from sick or dead birds and marine mammals. Officials also encourage reporting locations and unusual deaths to animal health authorities, supporting testing and tracking of the outbreak’s spread. The case at Beachport adds a mammalian species to the growing list of wildlife affected during Australia’s ongoing mainland H5N1 bird flu crisis.