South Australia holds the bulk of the infections, where testing confirmed the first mass mortality event from bird flu in Australian wildlife on an island off the state’s south-east coast.
Geographic Spread and Wildlife Impact
The outbreak spans five states, driven primarily by migratory seabirds bringing the virus across coastal regions. Avian influenza primarily impacts birds and poultry, causing severe disease and high mortality rates in high pathogenicity strains, though it can also spill over into mammals such as seals, cats, and cows.
Risk to Domestic Animals and Livestock
Domestic cats are particularly susceptible to the virus through contact with infected wild birds or by scavenging carcasses, according to University of Sydney wildlife and avian medicine specialist Michelle Campbell-Ward. The RSPCA advises pet owners to keep cats indoors and dogs on a lead in areas where the virus is active, noting that infected mammals can exhibit neurological symptoms such as tremors, seizures, walking in circles, drooling, or a runny nose. The RSPCA also recommends avoiding raw or unpasteurized animal-based diets.
Federal authorities report that the virus has not been detected in the Australian commercial livestock industry. However, a separate H7 bird flu outbreak in 2024 resulted in the cull of more than 10 percent of Australia’s laying hens—approximately 2.4 million birds—to contain that specific strain.
Human Health Risks and Global Context
Human infections with bird flu remain rare. According to the Australian Centre for Disease Control, transmission occurs when individuals come into contact with infected animals, their body fluids, or contaminated environments and subsequently touch their eyes, nose, or mouth, or breathe in contaminated dust.
Data from the US Centers for Disease Control and Prevention (CDC) shows that over a thousand global human cases of the H5 strain have been recorded since 1997. During a recent outbreak in the United States between February 2024 and late 2025, authorities logged 71 human cases and two deaths, largely linked to dairy herds and poultry farms. Globally, between August 2025 and the present, the CDC recorded 12 human cases of H5N1 in Bangladesh, Cambodia, and India, resulting in three deaths.
Most human cases result in mild illness rather than severe respiratory distress. NC State University virologist and immunologist Matthew Koci notes that the vast majority of US cases manifest as conjunctivitis, commonly known as “pink eye,” though global cases have occasionally led to severe pneumonia and death.
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