A highly lethal strain of avian influenza is rapidly spreading through Antarctica, threatening vulnerable wildlife populations, according to Chilean scientist Víctor Neira. The virus, detected initially in skuas on James Ross Island in April 2024, has now been confirmed in a dozen species along 900 kilometers of the continent’s western coastline.
Neira, a researcher at the University of Chile and the Chilean Antarctic Institute (INACH), warned that the observed strain is “capable of killing 100 percent” of infected fauna. Recent expeditions have identified cases in Antarctic cormorants, kelp gulls, Adelie and gentoo penguins, and, alarmingly, Antarctic fur seals.
“The virus has completely spread throughout the Antarctic region where we have the capacity to go and study,” Neira told AFP. The speed of the outbreak is particularly concerning, with the potential to decimate populations that, in some cases, number only around 20,000 individuals, such as Antarctic cormorants and skuas.
Genetic analysis of the virus, a clade 2.3.4.4b H5N1 strain, suggests it arrived in Antarctica via South America, according to a study published in Emerging Infectious Diseases in July 2025. The study, led by Neira, sequenced genomes isolated from the initial five infected skuas.
While the species currently affected are not classified as endangered by the International Union for Conservation of Nature, Neira cautioned that continued viral strengthening could rapidly change that status. A global wave of bird flu has impacted birds and mammals worldwide since 2021, including a significant outbreak that killed thousands of Humboldt penguins in Chile in 2023.
The spread of the virus is particularly worrisome given the unique vulnerability of Antarctic ecosystems. The continent, while hosting temporary scientific teams, lacks a permanent human population, making monitoring and intervention challenging. The outbreak at Bird Island, South Georgia, in 2024, marked the first documented case in the subantarctic region, highlighting the virus’s expanding reach.
