When you think of bird flu, you may conjure up images of chickens being slaughtered to stem an outbreak, or of migrating ducks, which can carry flu viruses from one continent to the next. Well, it's time to add penguins to your list of mental images.
Yes, Adelie penguins, which breed in huge colonies on the rocky Antarctic Peninsula, also harbor a version of the avian influenza virus, according to a study published in the journal, mBio.
Fret not. If a penguin happens to sneeze on you, you aren't going to get the flu. And, happily for the crowded colonies of nesting penguins, the avian influenza virus in their midst doesn't seem to make penguins sick, either.
But the discovery does raise intriguing questions about how flu viruses spread. And the finding leaves no doubt that the flu can get just about anywhere on Earth.
Researchers at a World Health Organization flu lab in Australia, led by Aeron Hurt, trekked down to the Antarctic Peninsula a year ago to look for the virus in the throats and, well, other cavities of Adelie penguins.
Previous research had hinted that penguins have come in contact with flu viruses. And researchers returned from the southern continent with proof positive. About 3 percent of the penguins they swabbed, from two distinct colonies, were infected but not suffering any obvious effects of a novel flu virus.
The scientists report that the virus is unlike any other flu virus found on the planet. That suggests that it has been isolated for many decades — presumably hiding out in the penguins' digestive and respiratory tracts, or possibly frozen in Antarctic ice.
How did it get there? Nobody can say for sure. But birds including the Arctic tern do migrate many thousands of miles, and might have brought a relative of this virus to Antarctica more than 50 years ago. Another possible suspect is the yellow-billed pintail duck, which is known to stray from South America and end up on the Antarctic Peninsula.
And don't assume that the black-and-white penguins are as tidy as their tuxedoed persona might suggest.
"The large amount of penguin feces in colonies during summer, which in some cases is so significant it can be observed on satellite images, presumably facilitates (viral) transmission by the fecal-oral route," the scientists note.
It's also possible that the virus can end up in seals and whales, they write. That means the virus could be carried around Antarctic waters. They speculate that the virus might mix and exchange genes inside these marine mammals, the way avian flu viruses found around human settlements sometimes recombine into nastier viruses inside pigs.
And while the scientists looked at the penguins in order to understand the myriad ways that flu can reach human beings, they came away more worried about the penguins themselves. Noting that South American birds do carry avian viruses that can be deadly to wildlife, "it is not inconceivable that such viruses could be transferred to the Antarctic continent by migratory birds, potentially resulting in catastrophic mass mortality," they write.
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