A deadly animal epidemic is on the verge of global spread. Scientists have officially documented the presence of the highly pathogenic avian influenza virus (HPAIV) in several species of birds and mammals in Antarctica, the most remote region of our planet, an icy refuge that has never before been surrounded by such a deadly species.

The H5N1 2.3.4.4b strain has spread rapidly from Europe to North America and South America, decimating wild bird and mammal populations worldwide since 2021.

Genetic analysis of the virus suggests it is likely to have begun to seep into the Antarctic region via birds migrating south. Scientists have long feared this moment would come. Iconic species of the region, such as albatrosses and penguins, are facing an existential crisis.

“Antarctica and sub-Antarctic islands have unique ecosystems that support populations of diverse bird species and marine mammals,” write the authors of a recent paper based on data from the British Antarctic Survey (BAS).

“Disease outbreaks with high mortality rates therefore pose a significant threat to already vulnerable seabird populations.”

It all started on September 17, 2023, when BAS researchers working on the South Georgia Islands noticed a giant petrel twitching and struggling to move, about halfway between Argentina and Antarctica.

When the bird died, brown skunks had eaten its carcass. On October 8, they too began twitching. Two days later, researchers recorded the largest number of bird deaths ever recorded among non-breeding birds on the islands. In early December, colonies of southern elephant seals and Antarctic fur seals were seen coughing, gasping, and taking short, sharp breaths.

Between October 8 and December 9, researchers counted a total of 33 bird carcasses and 17 mammal carcasses at eight different locations around the South Georgia Islands. Approximately 66 percent tested positive for HPAIV H5N1.

In the neighboring Falkland Islands, closer to Argentina in the southern Antarctic region, two more bird species, including black-browed albatrosses and southern fulmars, have tested positive for the virus. The virus has not yet officially reached the Antarctic mainland, but some researchers working on the western peninsula believe the animal outbreak has already reached the remote continent.

In March 2024, an international team of scientists presented research that has not yet been peer-reviewed on suspected cases of H5N1 in Adélie penguins and Antarctic crested penguins “at the southernmost latitude of Antarctica.”

Between December 2023 and January 2024, the team detected the virus in two breeding sites on the Antarctic Peninsula and the west coast of Antarctica. If confirmed, Australia would be the only continent where this strain of bird flu has not been found. There has also been no sign of spread in the wider Oceania region.

Benyard and colleagues explained that the animal outbreak was “particularly severe” in South America, causing mass mortality of both birds and marine mammals. Unlike other parts of the world, wildlife in South America has not been exposed to highly pathogenic avian viruses in recent history. Population mortality due to infection reaches 40 percent among some species.

The tragedy highlights “the significant ecological impact of HPAIV and the ongoing threat it poses to naive hosts,” the authors say. For some isolated species in Antarctica, this threat could be the nail in the coffin. Antarctic fur seals on Bird Island are already facing severe population declines, and penguin colonies on the mainland are experiencing catastrophic losses.

The last thing these birds and mammals need is a pandemic knocking on their door. The study was published in the journal Nature Communications.