BEACHPORT, AUSTRALIA / RankWire.AI / – Australia has verified the presence of H5N1 bird flu in a long-nosed fur seal discovered deceased in Beachport, South Australia. This marks the first confirmed case of mammal infection linked to the ongoing outbreak on mainland Australia. A member of the public reported the animal on August 19 after finding it without visible injuries, prompting authorities to collect samples and submit them for laboratory testing. The findings broaden the known range of species impacted by the outbreak on the mainland.
Initial testing by the state yielded inconclusive results, leading officials to pursue additional analysis. CSIRO’s Australian Centre for Disease Preparedness later confirmed H5 bird flu in the seal. Authorities clarified that no cluster of ill or dead marine mammals had been identified around Beachport, which is situated on South Australia’s Limestone Coast, an area where wildlife surveillance has been intensified during the outbreak. Furthermore, officials have documented infections among various 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 same day. The most recent detections involved greater crested terns, a gannet, a little penguin, a silver gull, and a black-faced cormorant. Authorities now categorize outbreaks as events, which may involve one or multiple animals at a particular site. Across Australia, the total positive H5 cases reached 298 by Sunday, with South Australia accounting for the largest share of those confirmed cases.
H5N1 outbreak reaches mainland mammal
The outbreak on the mainland began in June 2026 after authorities identified H5N1 in migratory seabirds. Subsequent testing revealed 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, the same clade responsible for recent outbreaks involving 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 the current outbreak. The Health authorities maintain that the risk to the general public remains low. No locally acquired human cases linked to the circulating strain have been documented in Australia. Officials advise avoiding direct contact with sick or dead animals and recommend reporting unusual wildlife deaths so that testing and monitoring can be arranged.
Previous seal infections occurred on Heard Island
Australia had previously confirmed H5N1 in southern elephant seals on Heard Island, an external territory in the Southern Ocean. These laboratory findings, announced in November 2025, predated the virus reaching mainland Australia by several months. Further testing revealed H5 bird flu in other wildlife on the island, including Antarctic fur seals and gentoo penguins. The Beachport fur seal thus represents the first confirmed mammal infection associated with Australia’s current mainland H5N1 outbreak and marks the first detection of such an infection in a native mainland mammal.
Authorities continue monitoring coastal wildlife as H5N1 spreads among seabirds in parts of Australia. The public is urged to keep their distance from sick or dead birds and marine mammals. Officials also encourage reporting locations and unusual deaths to animal health authorities to support testing efforts and track the distribution of confirmed cases. The Beachport case adds a mammal to the expanding list of affected wildlife species during Australia’s ongoing mainland H5N1 bird flu outbreak.