BEACHPORT, AUSTRALIA / RankWire.AI / – Australia has identified H5N1 avian influenza in a long-nosed fur seal found deceased at Beachport in South Australia. This marks the first confirmed case of a mammal infected in connection with the outbreak on mainland Australia. The authorities announced the laboratory findings following urgent testing of the animal’s samples. The discovery broadens the scope of the outbreak on the mainland beyond wild bird populations for the first time. Officials clarified that no evidence of a cluster involving other ill or deceased marine mammals in the vicinity has been found.
A member of the public reported the dead seal on August 19, noticing it showed no visible injuries. Initial tests by the state yielded inconclusive results, leading officials to send samples for additional analysis. CSIRO’s Australian Centre for Disease Preparedness later confirmed H5 bird flu in the seal. Beachport is located on South Australia’s Limestone Coast, an area where infections among wild seabirds have been documented. Since H5N1 reached mainland Australia earlier this year, this region has become one of several coastal zones impacted by the virus.
By August 23, South Australia had reported 194 confirmed H5 bird flu cases, including 11 new cases on that day. These outbreaks involved various species such as greater crested terns, a gannet, a little penguin, a silver gull, and a black-faced cormorant. The state now categorizes outbreaks as events, which may include one or multiple animals at a single site. Across Australia, a total of 298 positive H5N1 bird flu events had been recorded by Sunday, with South Australia accounting for the majority of those detections.
Mainland outbreak extends beyond wild avian populations
The outbreak on the mainland began after H5N1 appeared in migratory seabirds in June 2026. Subsequent testing confirmed the presence of the virus in native, non-migratory seabirds, including greater crested terns. As the situation developed, authorities observed a rise in affected wild bird populations across several states. During August, South Australia experienced a mass mortality event involving more than 1,000 greater crested terns. The virus circulating in Australia belongs to H5N1 clade 2.3.4.4b, a strain that has impacted wild birds, poultry, and mammals in different parts of the world.
Despite these wildlife detections, no infections have been reported among Australian poultry or other livestock species. The Health authorities continue to consider the risk to the general population as low. Australia has not recorded any locally acquired human cases involving the H5N1 strain linked to the current outbreak. Human infections typically require close contact with infected animals or contaminated environments, according to Health officials, who also advise avoiding contact with sick or dead birds and wildlife.
Previous H5N1 cases found in remote wildlife territories
In the past, Australia confirmed H5N1 in southern elephant seals on Heard Island, a remote external territory in the Southern Ocean. Laboratory results in November 2025 verified those infections, months before the virus was detected on the mainland. Further testing identified H5 bird flu in additional wildlife on the island, including Antarctic fur seals and gentoo penguins. The Beachport case is thus the first confirmed mammal infection associated with the current mainland outbreak. It also represents the first detection in a native mammal on the Australian mainland.
Wildlife surveillance continues as H5N1 circulates among seabirds along parts of Australia’s coast. Officials have urged the public to stay away from sick or dead wildlife and to report sightings, which can aid animal health teams in identifying new potential events and guiding testing efforts. Monitoring remains active across wildlife, agriculture, and public health sectors as the outbreak persists. The confirmed case involving the Beachport seal extends the range of species impacted by Australia’s ongoing H5N1 outbreak on the mainland.