- The bird flu virus that has raised the spectre of a new
flu pandemic causes 10 times as much inflammation in human lung cells as
regular flu, according to new research.
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- The finding could explain why H5N1 avian influenza is
so adept at causing fatal pneumonia and respiratory distress in people.
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- "This is the sort of thing you don't want a human
(influenza) strain to have," says University of Ottawa virologist
Earl Brown.
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- Scientists from the University of Hong Kong, working
with researchers in Vietnam, looked at the amounts of a group of proteins
called cytokines in human lung cells infected with the H5N1 bird flu virus,
which has infected at least 125 people so far in Southeast Asia, killing
64 of them.
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- When a virus or bacterium invades the body, the immune
cells kick out inflammatory chemicals called cytokines. But if the immune
system is over-stimulated, it can unleash a "cytokine storm,"
causing massive damage to tissues.
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- The researchers compared the levels of cytokines produced
by strains of the H5N1 bird flu that circulated in Hong Kong in 1997, and
in Vietnam in 2004, with a human flu virus.
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- Twenty-four hours after infection with H5N1, the human
lung cells contained 10 times the levels of the inflammatory proteins as
lung cells infected with a regular flu.
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- "This tells you what people (infected with bird
flu) are dying from," Mr. Brown said. "It's the same thing people
died from with SARS, this cytokine storm."
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- Finding a way to dampen down the immune response could
reduce the risk of life-threatening pneumonia and acute respiratory distress
in people infected with H5N1.
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- The research, published today in the journal Respiratory
Research, comes as Vietnam confirmed a 35-year-old man from Hanoi who was
hospitalized on Oct. 26 died three days later of H5N1 avian flu. It was
Vietnam's first confirmed case since late July. Since mid-December 2004,
the country, which is seeing new outbreaks of bird flu in poultry, has
reported 65 human cases, of which 22 were fatal.
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- Earlier this week, Indonesia confirmed two more cases
of human infection with H5N1 -- a 19-year-old woman from Tangerang, near
Jakarta, who died Oct. 28, and her eight-year-old brother, who was in hospital.
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- According to an update posted on the World Health Organization
website, investigators on the ground found signs of sick and dying chickens
in the area where the boy lived.
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- Meanwhile, the Canadian Food Inspection Agency said yesterday
it is still not known what type of bird flu strain has infected wild migratory
ducks in Quebec and Manitoba. Preliminary results found the birds were
infected with the H5 subtype. Officials are still awaiting tests to determine
the "N" type of the virus.
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- The birds -- 28 in Quebec and five in Manitoba -- were
healthy and there is no evidence of flu-related sickness among domestic
or wild birds in the areas where they were found.
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- Flu pandemics result when a bird and human flu mix genes,
or when bird flu adapts on its own to spread efficiently from humans to
humans.
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- Understanding what makes H5N1 bird flu so dangerous to
people "will lead to new strategies for managing human H5N1 disease
and enhance our preparedness to confront pandemic influenza, whether from
H5N1 or other influenza A subtypes," the researchers write in Respiratory
Research.
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- © The Ottawa Citizen 2005
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- http://www.canada.com/ottawa/ottawacitizen/news/story.html
?id=ef1848d9-6a93-4fc5-a0a5-687c30dde398
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