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March 13, 2025
Expedition finds H5N1 in 13 bird and seal species on the Antarctic Peninsula
When the H5N1 avian influenza virus began killing seabirds on the Antarctic Peninsula 1 year ago, scientists wondered how fast the deadly pathogen would spread on the remote continent and how much damage it would do to its rich wildlife.
Now, they have some answers. In the past 6 weeks, the sailboat Australis has traveled along the shores of the peninsula, whose northern tip is just 650 kilometers from South America. Eight researchers dressed from head to toe in protective gear disembarked at 27 sites to swab animals and test carcasses. They found the virus in all but three locales, affecting a total of 13 bird and mammal species. “The virus has reached every corner [of the peninsula] and is infecting almost every animal species,” says expedition leader Antonio Alcamí, a microbiologist with the Spanish National Research Council (CSIC).
So far there is no evidence that the virus has spread beyond the peninsula, a tongue of land extending north from the continent that makes up less than 5% of its land mass. Surveillance elsewhere has been limited, however. Large parts of the mainland are rarely visited and most research stations there do not have the capability to test for the virus.
“The situation in Antarctica is a bit of a black box,” says virus ecologist Michelle Wille of at the University of Melbourne, who was not involved in the expedition. “We’re still very much in the learning phase, so this new data is really important for us to better understand what is possibly going on.”
-snip-
Since January, the Australis has been on a new expedition funded by CSIC and the Spanish Association of Insurers. The ship, which has a lab that can detect viral RNA in samples, visited sites all along the peninsula’s west coast and in the Weddell Sea, on the eastern side. Researchers collected cloacal and tracheal swabs from live animals and brain tissue from carcasses. Out of 846 samples, 188 tested positive, from nine bird and four seal species.
Most of the dead animals were skuas, likely because they feed on infected carcasses. Skua populations appeared to have dwindled at sites the team visited last year.
-snip-
Another wave of infections could hit the continent from the Indian Ocean. In October 2024, hundreds of king penguins and elephant seal pups were found dead from H5N1 in the subantarctic Crozet and Kerguelen islands, equidistant from South Africa and Australia in the southern Indian Ocean. (Genetic analyses published in a preprint last week revealed the virus arrived there from the South Georgia Islands.) The archipelagos could serve as a springboard to other parts of Antarctica, but also to Australia, now the world’s only region free of H5N1 in the wild. “It’s a massive range expansion of the virus,” Wille says, “which is very, very concerning and shows that it has the capacity to spread more.
Expedition finds H5N1 in 13 bird and seal species on the Antarctic Peninsula
When the H5N1 avian influenza virus began killing seabirds on the Antarctic Peninsula 1 year ago, scientists wondered how fast the deadly pathogen would spread on the remote continent and how much damage it would do to its rich wildlife.
Now, they have some answers. In the past 6 weeks, the sailboat Australis has traveled along the shores of the peninsula, whose northern tip is just 650 kilometers from South America. Eight researchers dressed from head to toe in protective gear disembarked at 27 sites to swab animals and test carcasses. They found the virus in all but three locales, affecting a total of 13 bird and mammal species. “The virus has reached every corner [of the peninsula] and is infecting almost every animal species,” says expedition leader Antonio Alcamí, a microbiologist with the Spanish National Research Council (CSIC).
So far there is no evidence that the virus has spread beyond the peninsula, a tongue of land extending north from the continent that makes up less than 5% of its land mass. Surveillance elsewhere has been limited, however. Large parts of the mainland are rarely visited and most research stations there do not have the capability to test for the virus.
“The situation in Antarctica is a bit of a black box,” says virus ecologist Michelle Wille of at the University of Melbourne, who was not involved in the expedition. “We’re still very much in the learning phase, so this new data is really important for us to better understand what is possibly going on.”
-snip-
Since January, the Australis has been on a new expedition funded by CSIC and the Spanish Association of Insurers. The ship, which has a lab that can detect viral RNA in samples, visited sites all along the peninsula’s west coast and in the Weddell Sea, on the eastern side. Researchers collected cloacal and tracheal swabs from live animals and brain tissue from carcasses. Out of 846 samples, 188 tested positive, from nine bird and four seal species.
Most of the dead animals were skuas, likely because they feed on infected carcasses. Skua populations appeared to have dwindled at sites the team visited last year.
-snip-
Another wave of infections could hit the continent from the Indian Ocean. In October 2024, hundreds of king penguins and elephant seal pups were found dead from H5N1 in the subantarctic Crozet and Kerguelen islands, equidistant from South Africa and Australia in the southern Indian Ocean. (Genetic analyses published in a preprint last week revealed the virus arrived there from the South Georgia Islands.) The archipelagos could serve as a springboard to other parts of Antarctica, but also to Australia, now the world’s only region free of H5N1 in the wild. “It’s a massive range expansion of the virus,” Wille says, “which is very, very concerning and shows that it has the capacity to spread more.