A top World Health
Organization official says a new strain of bird flu in China that has already
killed 22 people and spread throughout seven provinces and municipalities is
one of the most lethal of its kind to date.
A group of WHO
specialists spoke with reporters Wednesday about the H7N9 virus, which has
already infected more than 100 people in China. The WHO team arrived late last
week for a five-day visit to learn more about the new virus.
According to Keiji
Fukuda, the WHO assistant director for health security, at this point, there is
still not enough evidence to show the virus can spread easily from human to
human.
“When we look at
influenza virus this is an unusually dangerous virus for humans…Based on the
evidence that we see we think that this virus is more easily transmitted from
poultry to humans than H5N1," he said.
The H5N1 strain of bird
flu surfaced in 2003. In the past decade, it has swept across three
continents and killed more than half of the 622 people it has infected.
WHO and Chinese health
officials stress the effort to understand the new strain is still in its early
stages.
Liang Wannian of the
National Health and Family Planning Commission says just how effective the
government’s prevention measures will be remains unclear. He says the extent of
the public health risk from the virus remains uncertain, as well.
"There are many
unknown factors, including the source of the virus, the mutation of the virus,
the pathogenicity, the virulence, the migration, the clinical symptoms and the
epidemiological situation of the virus, so we need to study a lot, there are so
many things that remained to be studied and learned," he said.
Chinese and WHO
scientists all agree that birds infected by the virus, especially poultry, are
the likely sources of human infection.
Nancy Cox, director of
the Flu Division at the U.S. Centers for Disease Control and Prevention was
also part of the WHO team.
"So far, no
samples from migratory birds or their habitats have been positive for
H7N9," Cox said. "In contrast, samples from chickens, ducks and
pigeons have been positive for H7N9 from poultry markets. Also
environmental samples taken from poultry markets have been positive."
So far, the majority of
deaths and infections from the new strain have occurred in Shanghai. Like many
other cities where the virus has cropped up, authorities there have closed down
live poultry markets, in response.
Anne Kelson, director
of the WHO Flu Research center in Melbourne Australia said the market closings
appear to be helping.
“We know that Shanghai
rapidly on April 6 closed down their poultry markets in that municipality and
it's been very encouraging to see that almost immediately there was a decline
in the detection of the new cases and the cases that did occur all occurred in
the next week, which you might expect to be within the incubation period of the
virus," she noted.
Still, Kelson added
that this is no reason to relax. She said close monitoring of the impact the
closure of such facilities should continue in the weeks and months to come.
Although Chinese
authorities said more than half of those infected have been individuals who had
direct contact with poultry or birds, how the remaining number of those
infected contracted the virus is less certain.
The government has
carried out tens of thousands of tests on birds but only several dozen have
turned up positive.
And, in one of the two
cases of bird flu in Beijing so far, a young boy contracted the virus, without
showing any symptoms of H7N9.
Sources :
http://www.voanews.com/content/who-describes-new-chinese-bird-flu-strain-as-lethal/1647796.html
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