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 represents the first confirmed case of mammal infection associated with the outbreak on mainland Australia. The authorities disclosed the laboratory findings following urgent testing of the sample from the animal. This discovery extends the scope of the mainland outbreak beyond wild birds for the first time. Officials also stated they had found no signs of a cluster involving other ill or deceased marine mammals nearby.
A member of the public reported the deceased seal on August 19, noting it showed no visible injuries. Initial testing by the state yielded an inconclusive result, prompting further sample analysis. CSIRO’s Australian Centre for Disease Preparedness later confirmed H5 bird flu in the seal. Beachport, located on South Australia’s Limestone Coast, is an area where authorities have documented infections among wild seabirds. Since H5N1 arrived on mainland Australia earlier this year, this region has become one of several coastal zones affected by the virus.
As of August 23, South Australia had reported 194 confirmed H5 bird flu incidents, with 11 new cases on that day alone. These cases involved greater crested terns, a gannet, a little penguin, a silver gull, and a black-faced cormorant. The state now tracks outbreaks as events, which can include one or multiple animals at a site. By Sunday, Australia had recorded a total of 298 positive H5 bird flu events nationwide, with South Australia accounting for the majority of these detections.
Mainland outbreak extends beyond wild bird populations
The outbreak on the mainland began after H5N1 emerged in migratory seabirds in June 2026. Subsequent testing confirmed the virus in native, non-migratory seabirds such as greater crested terns. Authorities then observed an increase in infected wild birds across multiple states. During August, South Australia experienced mass mortality events involving over 1,000 greater crested terns. The circulating virus in Australia belongs to H5N1 clade 2.3.4.4b, which has affected wild birds, poultry, and mammals in various parts of the world.
Despite wildlife detections, there have been no reported cases of H5 bird flu among Australian poultry or other livestock. The Health authorities maintain that the risk to the general population remains low. To date, no locally acquired human infections involving the H5N1 strain related to the current outbreak have been reported in Australia. Human infections typically require close contact with infected animals or contaminated environments, and officials advise avoiding touching sick or dead birds and other wildlife.
Previous H5N1 Cases Reported in Remote Australian Territories
Australia previously confirmed H5N1 in southern elephant seals on Heard Island, an isolated Australian external territory in the Southern Ocean. Laboratory tests verified these infections in November 2025, months before the virus appeared on the mainland. Further testing later identified H5 bird flu in additional wildlife on the island, including Antarctic fur seals and gentoo penguins. Consequently, the Beachport case is notable as the first confirmed mammal infection tied to the current mainland outbreak, as well as the first in a native mainland mammal.
Wildlife monitoring persists as H5N1 continues circulating among seabirds along Australia’s coast. Authorities have urged the public to avoid contact with sick or dead wildlife and to record any sightings. Such reports assist animal health teams in identifying new potential outbreaks and focusing testing efforts. Continuous surveillance across wildlife, agriculture, and public health sectors remains ongoing as the outbreak develops. The identification of the Beachport seal as infected adds a new mammalian species affected by Australia’s ongoing H5N1 outbreak on the mainland.