Australia confirms first H5 bird flu case in a mammal as dairy industry remains on alert

First mammal detection confirmed in South Australia

Australia has recorded its first confirmed H5 bird flu infection in a mammal after testing a long-nosed fur seal found dead at Beachport, 300 kilometres south of Adelaide. ABC News reported that the animal showed no signs of injury and was reported to the Emergency Animal Disease Hotline on August 19. Initial state testing was inconclusive before the infection was confirmed.

Federal Agriculture Minister Julie Collins described the case as concerning but not unexpected in an area with high infection rates among wild birds. Authorities believe the individual seal was probably exposed to infected birds or a shared environment. The detection was not associated with other sick or dead marine mammals at the time of the announcement.

ABC News reported 298 positive H5 bird flu events in Australia, including 194 in South Australia. The state had also recorded three mass-mortality events on remote offshore islands involving more than 1,000 greater crested terns. A suspected infection in a little penguin on Kangaroo Island was subsequently confirmed.

No infection detected in agricultural production

Despite the mammal case, Australian authorities say there is no evidence of H5 infection in poultry, dairy cattle or the wider agricultural production system. The Department of Agriculture, Fisheries and Forestry lists wildlife detections in Western Australia, South Australia, New South Wales, Queensland, Victoria and Tasmania.

An independent assessment commissioned by the Australian government and Dairy Australia rated the risk to the dairy industry as low. Completed in September 2025, it rated the risk to beef cattle, sheep and goats as negligible and the risk to pigs as low. A Parliamentary Library review nevertheless said the consequences of a dairy outbreak would be high and likely to be nationally significant.

Dairy Australia said the United States remained the only country where H5 bird flu had spread to dairy cattle. The organisation noted that the H5 genotype within clade 2.3.4.4b associated with US dairy outbreaks had not been detected in Australia when it issued its July 7 update. It said the available evidence did not justify changing the low-risk assessment for Australian herds.

Biosecurity becomes the immediate priority

The first mammal infection does not establish that Australian dairy cattle are infected or that the virus is moving between mammals. It does, however, demonstrate that the virus has crossed from its principal wild-bird hosts into another class of animal on the mainland. Authorities say H5 cannot be eradicated from wildlife, making surveillance and early detection central to protecting agricultural production.

Dairy Australia has formed an H5 Bird Flu Monitoring Team with Australian Dairy Farmers and the Australian Dairy Products Federation. Farmers have been advised to review their biosecurity plans, apply existing controls consistently and watch livestock and nearby wildlife for unusual illness.

Symptoms reported in infected dairy cattle overseas include:

• reduced milk production;
• loss of appetite;
• lethargy or reduced activity;
• thickened or abnormal milk;
• fever and other signs of illness.

Any outbreak in cattle could therefore affect farm output and impose additional testing, quarantine and animal-movement requirements. For now, there is no reported disruption to Australian milk production or supply. The market risk remains prospective, while the confirmed impact is concentrated in wildlife and the biosecurity workload facing governments and livestock producers.