A deadly strain of H5N1 avian influenza has been blazing through poultry farms and flocks of wild birds around the world, infecting mammals and even killing at least one polar bear. Now it’s knocking at the gates of Antarctica, just as dozens of species that have likely never experienced any strain of avian influenza are congregating to raise their next generation.

Avian influenza is currently causing big outbreaks on islands around the southern tip of South America, about 1,000 miles from the Antarctic Peninsula. The virus has led to clusters of illness in Gentoo Penguins on the Falkland Islands in January and in fur seals, elephant seals and other animals on the island of South Georgia last December. Scientists fear it will just require a short jump for the virus to hit the Antarctic Peninsula and spread into the rest of the continent.

Avian influenzas come in two varieties. Typically, wild birds catch mild cases of what scientists call “low-pathogenicity” flu, whereas farmed poultry species such as chickens and ducks can develop much more serious infections with “high-pathogenicity” strains. These different flavors can mix, creating more infectious viruses such as the one currently ravaging South America.

That combination, a substrain called clade 2.3.4.4b that developed within the past decade, comes from a lineage identified in China in the mid-1990s that has led to occasional outbreaks around the world. But clade 2.3.4.4b has now become a Frankenstein virus that combines the severe disease of poultry strains with a particular affinity for infecting wild birds. In addition to hitting South America, the virus has devastated seabird colonies in Europe, followed migratory birds south into Africa and jumped the Atlantic Ocean to infect even the regal California Condor.