- NEW YORK (AP) -- As
bad as this year's flu season is, it hasn't brought the worldwide outbreak
known as a pandemic. But experts warn that a pandemic is coming, it's just
a question of when. "It's going to happen," said Dr. Greg Poland
of the Mayo Clinic. "For the American public in particular, I think
it will be horrific."
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- Many Americans haven't experienced the overwhelming crush
of patients at hospitals and doctors' offices and the widespread fear a
flu pandemic could bring. And by historical pattern, Poland said it's about
time for the next one.
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- There have been three in the past 100 years, igniting
in 1918, 1957 and 1968. There's no way to predict when the next one will
appear, but the pattern does give experts pause.
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- It's all up to a virus that is variable and fickle, constantly
changing its genetic makeup, and the time when it hits upon a combination
that lets it take off worldwide is a "roll of the genetic dice,"
said Dr. William Schaffner of Vanderbilt University.
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- So the lack of a pandemic in the past 35 years basically
means "the genetic dice haven't been rolled that way," Schaffner
said. "While we're grateful for that, it makes us nervous."
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- There's plenty to be nervous about. It's estimated that
in the industrialized nations alone, the next pandemic is likely to send
1 million to 2.3 million people to the hospital and kill 280,000 to 650,000,
according to the World Health Organization. Its impact will probably be
greatest in developing countries.
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- As a practical matter, flu shots probably could not be
counted on to prevent a pandemic. For one thing, pandemic virus strains
emerge unexpectedly, and there would probably not be enough time to recognize
the threat and then provide vaccines that target them, Schaffner said.
What's more, many countries outside the United States wouldn't have the
means to give enough flu shots to stop the spread, Poland said.
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- Dr. Robert Couch of the Baylor College of Medicine noted
that health authorities are making major efforts to prepare for controlling
a pandemic, including putting an emphasis on developing and manufacturing
vaccines faster and in greater quantities.
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- The pandemic of 1918-19, known as the Spanish flu, sickened
an estimated 20 percent to 40 percent of the worldwide population, with
a death toll believed to exceed 20 million. In the United States alone,
some 500,000 people died. An ordinary flu epidemic kills an average of
36,000 Americans.
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- The next pandemic, the Asian flu of 1957-58, killed about
70,000 in the United States, while the 1968-69 Hong Kong flu led to about
34,000 deaths in the United States.
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- New strains of the flu virus, and so potential pandemics,
get their start in rural Asia, where the various strains that infect chickens
and other birds, pigs and humans can mingle. That gives them a chance to
swap genetic information as well as mutate on their own.
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- The potential spark for a pandemic occurs when that environment
produces a new virus that infects people and bears surface proteins that
people's bodies have never seen before. That means people have no natural
defense against it.
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- In contrast, ordinary outbreaks like this year's come
from a virus that has changed only slightly from previous ones, so that
the population it enters still has some natural immunity from encounters
with the previous germs.
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- But the genetic shift alone is not enough to launch a
pandemic. In addition, the new virus must acquire the ability to pass easily
from person to person, either by random genetic change or by picking up
genetic material from a previous human flu virus.
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- The world has had some close calls in the past few years,
says Richard Webby of St. Jude's Children's Research Hospital in Memphis.
In 1997, a bird flu in Hong Kong jumped to people, killing six. But the
virus never developed the ability to pass easily from person to person,
Webby said. Hong Kong authorities slaughtered 1.4 million chickens to end
the threat.
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- Just this year, authorities became alarmed when a father
and son in Hong Kong were hospitalized because of a bird flu virus, and
when flu virus infected some workers in the Netherlands who had slaughtered
infected chickens. The Netherlands outbreak was contained by anti-flu drugs
and fast vaccination, and slaughter of the poultry, Webby said.
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- Scientists have been noticing a lot of flu virus in chickens
and pigs globally, and a lot of variety in the strains, which is worrisome,
Webby said. It's impractical to develop vaccines against all the animal
strains in case they jump to humans, and there's no reliable way to identify
the most hazardous ones, he said.
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- When the next pandemic shows up, experts say, it will
find a population with many more vulnerable people like the elderly, infirm
and those with weakened natural defenses than were living 35 years ago.
It will also find a trimmed-down hospital system with fewer beds to handle
a surge of patients. And while today's anti-flu drugs will probably attack
the new strain, that's not yet clear. Supplies of the drugs and vaccines
would be strained.
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- But still, with the improvements in health care since
the last pandemic, might the next one be less serious?
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- "I want to believe that," Poland said, "but
we won't know until it happens."
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