- From within the glossy, feathered bodies of crows, scientists
have discerned an unsettling clue to the virulence of the West Nile virus
sweeping the United States.
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- The preliminary research suggests the germ is a mutated
strain far deadlier to birds than West Nile strains in most other parts
of the world.
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- Whether it's more dangerous to humans, too, is an open
question, but the virus has already caused more cases of neurological illness
in people in this country than anywhere else, ever.
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- That combination of facts has public health officials
on edge as warm weather brings forth new legions of mosquitoes carrying
West Nile virus between birds, humans and other susceptible animals.
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- West Nile virus is a new disease for the United States,
first identified in this country in 1999 with an outbreak in New York.
It's been a recognized illness since 1937, when the West Nile pathogen
was found in the African country of Uganda.
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- But there and in most parts of the world where it has
surfaced, the virus typically causes illness akin to the flu, bringing
fever, headache, muscle aches and fatigue -- unpleasant, but rarely fatal.
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- It wasn't until 1996 in Romania that an outbreak of West
Nile virus caused a significant number of cases of encephalitis and meningitis,
life-threatening inflammations of the brain and central nervous system
-- 500 cases in that event, according to Dr. Grant Campbell, an epidemiologist
with the national Centers for Disease Control and Prevention.
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- That incidence of West Nile virus "neuroinvasive"
disease stood as the world's largest until 2002, when the United States
logged nearly 3,000 such cases. Last year was almost equally bad, with
nearly 3,000 more. The virus has killed about 550 people in the United
States in the past two years. No human cases have been confirmed in the
country so far this year.
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- "We don't know what to expect in 2004, frankly,"
said Campbell, who works at the CDC's Arbovirus Diseases Branch in Fort
Collins, Colo.
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- But, he added, the outlook isn't good.
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- "One of the ominous things that happened last year
... was that the Northeast had more cases than it ever had. That's ongoing
(disease) activity for five years," Campbell said. "It may suggest
that that's the way the world's going to be over the next few years."
Trying to decipher what distinguishes the U.S. epidemic from others in
the world, researcher Aaron Brault focuses on the virus's effect on birds,
which are the hardest-hit of its victims. West Nile virus is mainly a disease
of birds; people and other susceptible animals, such as horses, are merely
passers-by.
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- Now an assistant professor of pathology, microbiology
and immunology at the University of California-Davis, Brault worked until
a year ago for the CDC in Colorado, where he studied the effects of three
different strains of West Nile virus on small groups of crows.
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- One strain came from Africa, one from Australia and one
from the United States. The differences were pronounced.
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- Looking at the crows, you wouldn't have known their bodies
were infected with the same bug. "You walk into one room and every
bird's hunched over and sick. You walk into another room and every bird's
flying around and squawking," Brault said.
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- He said the birds infected with the Australian strain
didn't appear sick, for the most part. The birds infected with the African
strain became somewhat ill, and a few died after a bout of sickness lasting
more than a week.
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- All the birds infected with the United States strain
died. And quickly, on the order of five days. Despite the risk to public
health, West Nile virus is not a danger to most individuals. Researchers
believe that out of 150 people infected with the virus, 120 people won't
feel sick at all.
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- Copyright © 2004 by the Casper Star-Tribune published
by Lee Publications, Inc., a subsidiary of Lee Enterprises, Incorporated
http://www.casperstartribune.net/articles/2004/05/19/news/wyomi
ng/0d94c697aea90dfa87256e9900089bc8.txt
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