Scientists have discovered a new strain of avian influenza virus (AIV) in Antarctic penguins, suggesting that the frozen continent may be more vulnerable to introduced pathogens than had been thought.
The virus, which was discovered in a chinstrap penguin on the Antarctic Peninsula, was highly similar to a North American strain, meaning it was introduced recently. The discovery, by a team led by Aeron Hurt of the Melbourne-based Peter Doherty Institute for Infection and Immunity, was published in the Journal of Virology.
It's not the first time that bird flu has been found in Antarctic penguins. In 2013, after collecting swabs, blood and feces from several species, Hurt and colleagues found a different strain in Adélie penguins; they also found it the following year, which Hurt said might mean that the virus can survive an Antarctic winter and resurface the following summer as migrating penguins return.
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Genetic analysis of that virus suggested it diverged from other strains between 49 and 80 years ago, meaning it had likely been in the Antarctic for decades. Its discovery prompted Hurt and colleagues to hypothesize that Antarctica was the "ultimate 'AIV evolutionary sink', whereby new strains are introduced into the region only on rare occasions, but once introduced, can become endemic within the local bird population and over time become highly diverged from other AIVs on the planet." However, the latest discovery suggests that Antarctica may be more vulnerable to introductions of new strains than previously thought.
The scientists also found bird flu virus in a snowy sheathbill, a scavenging bird that steals krill and fish from penguins and also preys on chicks. That species sometimes flies north to the Falkland Islands and the southern tip of South America, suggesting that it or other migratory species like Arctic terns or skuas are the most likely pathways of infection.
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The authors emphasize that the percentage of samples in which viruses were found was very low -- and of three penguin species studied, no gentoo penguins have been found to be infected -- and the virus does not appear to have made any of the birds ill. But the fact that such viruses can apparently find their way to Antarctica is a cause for some concern.
"The impact of a pathogenic influenza virus, one that causes death or severe illness in birds, would have a really devastating impact," Hurt said.
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