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August 7, 2004
ATLANTA -- The number of West Nile virus cases
has tripled to at least 164 since last week and
will likely break last year's record, a top
federal health official said Thursday in the latest
warning about the rapid advance of the mosquito-borne
disease.
"The
numbers are starting to change very, very quickly,"
said Dr. Julie Gerberding, head of the Centers for
Disease Control and Prevention. "That is very
concerning."
State
health officials report seven people -- all of them
elderly -- have died from the virus. Four of the
deaths were reported in Colorado, the hardest-hit
state.
Health
officials had expected the disease to spread this
year to all corners of the country, invading Western
states previously unscathed. But they appeared somewhat
surprised at its speed.
"It
indicates we are starting the epidemic with more
cases than last year," Gerberding said. She
warned of "a great number of infected people."
Nationwide,
the CDC said at least 164 people in 16 states are
infected, compared with 59 a week ago. The latest
figures do not include new cases reported by Colorado
health officials, which the CDC had not verified.
Last
year, 4,156 people caught the virus, and 284 died.
There were 112 cases in four states at this point
in 2002, when the United States suffered the biggest
reported outbreak of West Nile encephalitis in the
world.
West
Nile virus rarely kills, but about 1 in 150 people
who get it will develop its potentially deadly encephalitis
or meningitis. Most often, it affects the elderly.
Of its seven victims this year, the youngest was
68.
West
Nile virus, a virus known to be hosted by 18 species
of native wild birds and spread by mosquitoes, was
first confirmed in the United States August 1999.
An outbreak of West Nile encephalitis was contained
within the New York City and Long Island regions between
August 5, 1999 and September 16, 1999. Since then,
the virus has been found in Connecticut, Maryland
and Eastern Upstate New York. In July of this year
dead birds in the Boston area have been confirmed
as having the disease. West Nile encephalitis is an
infection of the brain caused by the virus and can
be fatal to humans.
The
disease is transmitted to humans when a mosquito feeds on
an infected bird and then feeds on a human during the virus
incubation period, which is 10 to 14 days. Most infections
are mild and symptoms of West Nile encephalitis include
fever, headache, body aches, skin rash and swollen lymph
glands. More severe infections may be marked by high fever,
neck stiffness, stupor, disorientation, coma, tremors, convulsions,
muscle weakness, paralysis, and in some cases, death. The
Centers for Disease
Control and Prevention (CDC) recommends that immediate
medical care should be sought if you believe you may have
contracted West Nile encephalitis.
According
to the CDC
case fatality rates range from 3% to 15% and are highest
in the elderly population. In the New York epidemic of 1999
seven deaths occurred in sixty-two cases of severe disease.
People who are most at risk for contracting severe symptoms,
in addition to the elderly, are young children and those
with weakened immune systems. The CDC
recommends reducing the risk of becoming infected by:
- limiting
time outdoors during dawn, dusk and early evening
- wearing
long-sleeved shirts and long pants when outdoors
- using
an effective insect repellent
David
Kern of DAK Pharmaceuticals, maker of GreenHead
repellent adds that "because mosquitoes will bite through
thin clothing, repellent should be applied to clothing as
well as to exposed skin." The choice of insect repellent
should be based on three factors; the level of mosquito
infestation, the length of time one will be exposed to them
and the age of the person. Using a 20 30% concentration
of a DEET-based repellent will provide effective protection
for up to 4 hours exposure to heavy infestations. Higher
concentrations of DEET will give
longer-lasting protection according to Kern whose company
markets GreenHead Tick and Insect Repellent
in a formula of 30% DEET.
Plant-derived
formulas, such asthose with a 5 or 10% citronella concentration,
will provide effective mosquito repellency for short periods
of time and need to be reapplied to maintain protection.
Studies show that citronella can be an effective repellent,
but it provides much shorter protection time than most DEET-based
products. Frequent reapplication of the repellent can partially
compensate for this. but Deet-based products are by far
and away the most effective repellent.
Because
the West Nile virus had never been reported in the United
States before last year, and the migration of the disease
from the New York area to Boston, Kern emphasized the importance
of protection against mosquito bites. He especially recommends
that people who could be most seriously affected by West
Nile encephalitis, keep insect repellent in their automobiles,
recreation vehicles, and with the tools and other items
they use outdoors during mosquito season.
More
information can be found online at http://www.cdc.gov.
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