Authorities in South Australia have identified a second long-nosed fur seal suspected of carrying the H5 high-pathogenicity avian influenza virus [1].
The discovery raises urgent concerns that the virus could spread to other marine mammals, including the endangered Australian sea-lion population. Officials said such a spread could trigger a mass-mortality event across the region's coastline [3, 5].
This suspected case was reported on Monday, coming just one day after the first confirmed mammal case in the country [2, 4]. The second seal was found on the same island as the first identified animal [1, 3]. This sequence of events marks the first detection of H5 bird flu in a mammal within Australia [3].
Wildlife experts and government officials are monitoring the situation closely as the virus moves through the animal population. The proximity of the two cases suggests a localized cluster on the island, though the risk of wider transmission remains high. The H5 strain is known for its high pathogenicity, meaning it can cause severe disease and death in susceptible species [1, 2].
While the first case was confirmed, the second remains a suspected infection. Testing and surveillance are ongoing to determine the extent of the viral load, and the possibility of further transmission to other species in the South Australian waters [1, 3].
“The discovery raises urgent concerns that the virus could spread to other marine mammals.”
The jump of H5 avian influenza from birds to mammals is a critical biological milestone. While the current cases are limited to seals, the potential for the virus to enter endangered populations like the Australian sea-lion could lead to irreversible biodiversity loss. This pattern of infection suggests the virus is adapting to mammalian hosts, which typically increases the surveillance priority for public health officials monitoring zoonotic risks.
