BEACHPORT, AUSTRALIA / RankWire.AI / – Australia has verified the presence of H5N1 bird flu in a long-nosed fur seal discovered dead at Beachport in South Australia. This incident marks the first confirmed mammal case associated with the outbreak on mainland Australia. Following urgent testing of the animal’s samples, authorities announced the laboratory results, which confirmed the infection. This discovery expands the outbreak on the mainland beyond wild birds for the first time, though officials reported no signs of a cluster involving other sick or deceased marine mammals nearby.
A member of the public found the dead seal without apparent injuries on August 19 and reported it. Initial tests conducted by the state yielded inconclusive results, leading officials to send samples for additional analysis. CSIRO’s Australian Centre for Disease Preparedness later confirmed the presence of H5 bird flu in the seal. Beachport is located on South Australia’s Limestone Coast, an area where infections among wild seabirds have previously been recorded. Since H5N1 reached mainland Australia earlier this year, several coastal locations, including this one, have been affected.
By August 23, South Australia had documented 194 confirmed H5 bird flu incidents, including 11 new cases reported on that day involving greater crested terns, a gannet, a little penguin, a silver gull, and a black-faced cormorant. The state now considers outbreaks as events, which may involve one or multiple animals at a specific location. Across Australia, 298 positive H5N1 bird flu events had been recorded by Sunday, with South Australia accounting for the majority of these detections.
Outbreak Extends Beyond Wild Bird Cases on Mainland
The mainland outbreak began when H5N1 was identified in migratory seabirds in June 2026. Subsequent testing confirmed the virus in native, non-migratory seabirds, including greater crested terns. As a result, authorities observed increasing numbers of affected wild birds across various states, with South Australia reporting the mass death of over 1,000 greater crested terns during August. The circulating virus in Australia belongs to H5N1 clade 2.3.4.4b, which has previously impacted wild birds, poultry, and mammals elsewhere in the world.
Despite these wildlife infections, there have been no reports of H5 bird flu affecting Australian poultry or other livestock. The Australian Centre for Disease Control continues to assess the risk to the general public as low. Australia has yet to record any locally acquired human cases of the H5N1 strain involved in this outbreak. Health authorities note that human infection generally requires close contact with infected animals or contaminated environments and recommend avoiding touching sick or dead birds and wildlife.
Previous H5N1 Cases Found on Remote Territories
H5N1 was previously confirmed in southern elephant seals on Heard Island, an isolated Australian external territory in the Southern Ocean, with laboratory tests confirming these infections in November 2025—several months before the virus appeared on the mainland. Additional testing identified H5 bird flu in other wildlife on the island, including Antarctic fur seals and gentoo penguins. The Beachport incident is therefore the first confirmed mammal case linked to the current mainland outbreak and the first detection in a native mainland mammal.
Wildlife surveillance continues as H5N1 circulates among seabirds along parts of Australia’s coastline. Authorities have urged the public to avoid contact with sick or dead wildlife and to report sightings, which assist animal health teams in identifying new potential cases and directing testing efforts. Monitoring remains active across wildlife, agriculture, and public health systems as the outbreak progresses. The confirmed case involving the Beachport seal adds a mammal to the list of species affected by Australia’s ongoing mainland H5N1 outbreak.