H10N8 is the latest bird flu to come out of China and, potentially, decimate humanity like in that Gwyneth Paltrow movie. You may have previously been mortally frightened by news about H1N1, which killed up to 100 million people in 1918 and another 15,000 in 2009 and 2010. Or maybe you’ve been reading about H7N9, which has been connected to just about 100 human deaths and is the cause of a massive poultry cull in Hong Kong this week:
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A health officer packs dead chickens at a wholesale poultry market in Hong Kong.
Reuters/Tyrone Siu
Is
H10N8 10 times more deadly than H1N1—or is it eight times, or 80? Not
at all. The names refer to the two kinds of spiky protein that influenza
A viruses wear on their surfaces, all the better to burrow into the
hosts’ cells. H is for hemagglutinin and there are 16 varieties; N is for neuraminidase and there are nine different kinds. All told there are 144 different types of influenza A, from H1N1 to H16N9, all of which are found in birds and some of which are also found in horses, pigs, and humans.
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Information is beautiful
So
why do new versions keep popping up to infect humans? That’s where
promiscuous virus behavior comes in. The influenza A virus is fond of a
little trick known as reassortment, which means that two viruses
infecting the same cell can swap genetic components such as
hemagglutinin and neuraminidase proteins. So a chicken in China
(virtually all new influenza strains arise in southeast and eastern Asia
because of the close contact between humans and livestock) that has two
known flu types can give rise to a novel third strain.
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CDC
To
complicate matters, a virus can mix and match any of its eight
genes—not just the H and N proteins—and can incorporate genetic material
from swine, avian, and human flu strains.
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virology.ws