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Bird flu virus mutating into
human-unfriendly form
Maggie
Fox
Reuters
Sunday October 07, 2007
The H5N1 bird flu virus
has mutated to infect people more easily, although it still has
not transformed into a pandemic strain, researchers said on Thursday.
The changes are worrying, said Dr. Yoshihiro Kawaoka of the University
of Wisconsin-Madison.
"We have identified a specific change that could make bird
flu grow in the upper respiratory tract of humans," said
Kawaoka, who led the study.
"The viruses that are circulating in Africa and Europe are
the ones closest to becoming a human virus," Kawaoka said.
Recent samples of virus taken from birds in Africa and Europe
all carry the mutation, Kawaoka and colleagues report in the Public
Library of Science journal PLoS Pathogens.
(Article continues below)
"I don't like to scare the public, because they cannot do
very much. But at the same time it is important to the scientific
community to understand what is happening," Kawaoka said
in a telephone interview.
The H5N1 avian flu virus, which mostly infects birds, has since
2003 infected 329 people in 12 countries, killing 201 of them.
It very rarely passes from one person to another, but if it acquires
the ability to do so easily, it likely will cause a global epidemic.
All flu viruses evolve constantly and scientists have some ideas
about what mutations are needed to change a virus from one that
infects birds easily to one more comfortable in humans.
Birds usually have a body temperature of 106 degrees F, and humans
are 98.6 degrees F usually. The human nose and throat, where flu
viruses usually enter, is usually around 91.4 degrees F.
"So usually the bird flu doesn't grow well in the nose or
throat of humans," Kawaoka said. This particular mutation
allows H5N1 to live well in the cooler temperatures of the human
upper respiratory tract.
H5N1 caused its first mass die-off among wild waterfowl in 2005
at Qinghai Lake in central China, where hundreds of thousands
of migratory birds congregate.
That strain of the virus was carried across Asia to Africa and
Europe by migrating birds. Its descendants carry the mutation,
Kawaoka said.
"So the viruses circulating in Europe and Africa, they all
have this mutation. So they are the ones that are closer to human-like
flu," Kawaoka said.
Luckily, they do not carry other mutations, he said.
"Clearly there are more mutations that are needed. We don't
know how many mutations are needed for them to become pandemic
strains."
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INFOWARS:
BECAUSE THERE'S A WAR ON FOR YOUR MIND
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