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Last month, Spanish researchers confirmed that H5N1, the highly pathogenic form of avian influenza, had finally turned up—as long feared—in Antarctica, in two dead birds called skuas near an Argentine research station. And last week, a Chilean-led expedition reported the virus in Adélie penguins and a cormorant (see map, below). The full extent of the outbreak is unknown, but the arrival of the virus “is a really big issue,” says Thierry Boulinier, a disease ecologist with the French national research agency CNRS. “It is likely that it will spread in Antarctica among densely breeding seabirds, notably penguins, and be responsible for further dramatic die-offs.”
In remote Antarctica, the scattered reports so far suggest far fewer bird deaths than expected. Still, concern remains high. At Beagle Island off the Antarctic Peninsula, researchers from the University of Chile and other institutions have found seven Adélie penguins that were infected yet have remained healthy. An Antarctic cormorant on western Graham Land was also infected yet apparently unharmed. This raises the chances that these birds could transmit the virus to new locations, especially if these or other birds are contagious when they congregate in the austral spring for breeding. “A healthy carrier of the virus could be much more dangerous than an animal that gets infected and dies,” says Marcela Uhart, a wildlife veterinarian at the University of California, Davis.