- HONG KONG (Reuters) -- The
unusually large number of ducks dying from bird flu in southern China indicates
the bug has become more virulent, which will put more people at risk of
contracting it, Hong Kong scientists said on Wednesday.
-
- They also raised the alarm about chilled and frozen poultry
meat, saying the deadly H5N1 virus could survive for years in temperatures
as low as minus 70 degrees Celsius (-94 F), but repeated that it can be
killed if meat is cooked properly.
-
- China confirmed on Tuesday that H5N1 had killed ducks
in southern Guangxi province, making it the tenth place in Asia to be afflicted
with a disease that has killed eight people in the region in the last few
weeks.
-
- "H5 viruses are generally less fatal to ducks, so
it is uncommon for so many ducks to die. This means this particular H5N1
strain has become more virulent," said virologist Leo Poon from the
University of Hong Kong.
-
- "This means it can cause extensive deaths in poultry
and this may in turn increase the chance of more people contracting it
(if they come in direct contact with sick birds)."
-
- The flu has devastated poultry populations wherever it
has appeared, and the greatest fear is that the H5N1 avian flu virus might
latch onto human influenza and unleash a pandemic among people with no
immunity to it.
-
- The avian flu strain first jumped from chicken to human
in 1997 in Hong Kong, infecting 18 people and killing six of them. Then,
experts considered ducks to be the original host of the H5N1, although
the waterfowl were usually not taken ill by the bug.
-
- Scientists said they could not rule out the possibility
that the new, more powerful bird flu strain might make the jump from human
to human less difficult. So far, most of those infected were in close contact
with chickens at home or on farms.
-
- "If virulence goes up, it would trigger larger outbreaks
and more poultry deaths...and this increases the chance of human to human
transmission," Poon said.
-
- SIGNS VIRUS HAS MUTATED
-
- Hong Kong has already banned the import of chicken from
places affected by the bird flu, and Poon urged the government to begin
stringent checks on chilled and frozen chicken and ducks in stores and
warehouses and on future imports.
-
- "We must check the source of chilled and frozen
chicken and we must do it at once," Poon said.
-
- Although the virulence of the current strain indicates
the virus has mutated, experts were divided over whether the vaccine used
in Hong Kong and parts of mainland China to inoculate chickens against
the bird flu is still useful.
-
- The vaccine was cultured from the milder H5N2 virus.
-
- "It still serves to prevent H5N1," Poon said.
-
- But Frederick Leung, dean of science at the University
of Hong Kong, was more circumspect.
-
- "This H5N2 vaccine provides cross-protection and
effectiveness in 80 percent of chickens. But it is based on the 1997 strain.
If there has been a mutation, any scientist will tell you the protection
will be less than 80 percent, or even none," Leung said.
-
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