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 time a mammal infection has been confirmed in connection with the current outbreak on mainland Australia. A member of the public reported the animal on August 19 after noticing it was without visible injuries. Authorities collected samples and dispatched them for laboratory analysis. The findings expanded the known range of affected species associated with the mainland outbreak.
Initial testing at the state level yielded an inconclusive result, prompting further testing. CSIRO’s Australian Centre for Disease Preparedness subsequently confirmed H5 bird flu in the seal. Officials clarified that they had not identified a cluster of sick or deceased marine mammals around Beachport. The town is situated on South Australia’s Limestone Coast, where wildlife surveillance efforts have increased during the outbreak. Authorities have also 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 day. The most recent detections involved greater crested terns, a gannet, a little penguin, a silver gull, and a black-faced cormorant. Now, outbreaks are recorded as events that may involve one or multiple animals at a location. Throughout Australia, authorities reported a total of 298 positive H5 events by Sunday. South Australia accounted for the largest share of these confirmed cases.
H5N1 outbreak extends to mammal on mainland Australia
The outbreak on the mainland started 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. This same clade has caused infections in wild birds, poultry, and mammals in multiple regions outside Australia during recent outbreaks.
Authorities have not found any infections in Australian poultry or other livestock linked to the current outbreak. The Australian Centre for Disease Control continues to evaluate the risk level to the general population as low. Australia has not reported any locally acquired human cases related to the strain currently circulating among wildlife. Health officials advise avoiding direct contact with sick or dead animals and recommend reporting unusual wildlife deaths to enable testing and monitoring efforts.
Previous H5N1 infections found in seals on Heard Island
Australia previously confirmed H5N1 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 before the virus reached the mainland. Later testing identified H5 bird flu in additional wildlife on the island, such as Antarctic fur seals and gentoo penguins. The Beachport fur seal therefore represents the first confirmed mammal infection linked to Australia’s current mainland H5N1 outbreak and the first such detection in a native mainland mammal.
Authorities continue to monitor coastal wildlife as H5N1 spreads among seabirds across regions of Australia. The public has been advised to keep their distance from sick or deceased birds and marine mammals. Officials also encourage reporting unusual deaths and locations of affected animals. These reports facilitate testing and tracking the spread of confirmed events. The case at Beachport adds a mammal species to the expanding list of wildlife affected during Australia’s ongoing mainland H5N1 bird flu outbreak.