BEACHPORT, AUSTRALIA / RankWire.AI / – Australia has confirmed H5N1 bird flu in a long-nosed fur seal found dead at Beachport in South Australia. The case marks the first confirmed mammal infection linked to the outbreak on mainland Australia. Authorities announced the laboratory result after urgent testing of samples from the animal. The finding extends the mainland outbreak beyond wild birds for the first time. Officials said they had found no evidence of a cluster involving other sick or dead marine mammals nearby.
A member of the public reported the dead seal on August 19 after finding it without visible signs of injury. Initial state testing produced an inconclusive result, prompting officials to send samples for further examination. CSIRO’s Australian Centre for Disease Preparedness later confirmed H5 bird flu in the seal. Beachport sits on South Australia’s Limestone Coast, where authorities have recorded infections among wild seabirds. The area has become one of several coastal locations affected since H5N1 reached mainland Australia earlier this year.
South Australia had recorded 194 confirmed H5 bird flu events by August 23, following 11 new confirmations that day. Those events included infections involving greater crested terns, a gannet, a little penguin, a silver gull and a black-faced cormorant. State authorities now count outbreaks as events, which can involve one or more animals at a location. Australia had recorded 298 positive H5 bird flu events nationally by Sunday. South Australia accounted for the largest share of those reported detections.
Mainland outbreak spreads beyond wild birds
The mainland outbreak began after H5N1 appeared in migratory seabirds in June 2026. Testing later confirmed the virus in native, non-migratory seabirds, including greater crested terns. Authorities subsequently recorded growing numbers of affected wild birds across several states. South Australia also reported mass mortality involving more than 1,000 greater crested terns during August. The virus circulating in Australia belongs to H5N1 clade 2.3.4.4b, which has affected wild birds, poultry and mammals in other parts of the world.
Despite the wildlife detections, authorities have reported no H5 bird flu infections in Australian poultry or other livestock. The Australian Centre for Disease Control continues to classify the risk to the general population as low. Australia has recorded no locally acquired human cases involving the H5N1 strain detected in the current outbreak. Health authorities say human infection generally requires close contact with infected animals or contaminated environments. They also advise people to avoid touching sick or dead birds and other wildlife.
Earlier H5N1 cases occurred on remote territory
Australia had previously confirmed H5N1 in southern elephant seals on Heard Island, a remote Australian external territory in the Southern Ocean. Laboratory testing confirmed those infections in November 2025, months before the virus reached the Australian mainland. Further testing later detected H5 bird flu in additional wildlife on the island, including Antarctic fur seals and gentoo penguins. The Beachport case therefore represents the first confirmed mammal infection connected with the current mainland outbreak. It also marks the first such detection in a mainland native mammal.
Authorities continue wildlife surveillance as H5N1 circulates among seabirds along parts of Australia’s coast. Officials have asked the public to keep away from sick or dead wildlife and record the location of any sightings. Reports can help animal health teams identify possible new events and direct testing to affected areas. Authorities have maintained monitoring across wildlife, agriculture and public health systems as the outbreak develops. The confirmed Beachport seal case adds a mammal to the range of species affected by Australia’s mainland H5N1 outbreak.