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West
Nile (WN) virus. You’ve heard a lot about it in the news over
the past
year or so, but what is WN
virus, and should we be concerned about it here in Arkansas?
Fatal encephalitis,
an infection of the brain in humans, horses, other animals and
many types of birds, is the most serious complication of WN
virus. The virus was first discovered in the West
Nile District of Uganda in 1937. It was the source of
severe human meningoencephalitis (an infection of the spinal cord
and brain) during a 1957 outbreak in Israel.
How does the WN virus spread?
We know that the virus can be found in many wild and domesticated
animals including cattle, sheep, pigs, goats, camels, rabbits,
dogs, rodents, primates and bats. Experts believe that wild
and domestic birds are the primary host. Spread from birds
to man and other animals results from mosquitos feeding on an
infected bird and then biting a host (man).
Each year, from mid-August to
November, hundreds of millions of birds cross Israel as they
migrate from Europe to the warmer African climates. Some of them
carry WN virus, which is picked up by mosquitoes and spread
quickly to humans, causing sickness ranging from flu-like illness
to encephalitis. Over 120 cases of WNV and eight deaths have
occurred in Israel during the year 2000 alone.
Hundreds of additional cases are
suspected.
In the summer and fall of 1999, the
first cases ever of WN virus infection occurred
in the northeastern United States. The original eight diagnosed
cases, all previously healthy adults between the ages of 58 and
85, were found to be within a four-mile area of Queens, New York.
What was the outcome of the 1999
outbreak?
- Seven deaths and 62 people
clinically ill;
- 25 cases in horses with nine
deaths;
- and, at that time, at least 14
different species of birds dead of the infection.
Unfortunately, the disease did not
die out over the winter months. Mosquito control efforts
didn’t prevent the virus from spreading during the year
2000. The affected states where human or other animal
infection has been recognized are Connecticut, Delaware, Maryland,
Massachusetts, New Hampshire, New Jersey, New York, North
Carolina, Pennsylvania, Rhode Island, Vermont, Virginia and the
District of Columbia. Experts predict that within a few
years, WN virus will be nationwide.
During the year 2000, there were 18
cases reported in humans in the U.S.; New York reported 14 of the
cases and New Jersey had four (one of these 18 cases resulted in
death). In addition, WN virus infected animals included
4,139 WN birds in 12 states and 65 horses in seven states.
The WN virus comes on
suddenly. Symptoms may include:
- fever;
- stomach pain;
- stiff neck, headache, slurred
speech, blurred vision, memory loss, confusion and
coordination loss;
- and muscle weakness.
However, most infected people show
little or no symptoms and recover completely. The elderly are more
susceptible are more likely to develop encephalitis or meningitis.
What’s being done in Arkansas to
prepare for the possibility of WN virus? The Centers
for Disease Control has provided grant money to the Arkansas
Department of Health to develop a program to detect WNV
encephalitis in humans, birds and horses in Arkansas.
If the disease appears in Arkansas,
the best way to combat it is to reduce the mosquito population by
spraying with a synthetic product. Standing water must be treated
and stagnant water should be eliminated.
Remember that WN virus has not made
it to Arkansas, but if it does, you can protect yourself by
wearing long sleeve shirts and pants when outdoors in mosquito
infested areas. Also, it may be necessary to spray your exposed
skin areas and clothes with an insect repellant.
The Livestock
and Poultry Commission, in cooperation with the Arkansas
Department of Health, will be testing dead birds and horses for
the virus. If you should see a clustering of dead birds,
especially crows, call Dr.
Thomas McChesney, state epidemiologist, Arkansas Department of
Health at (501) 661-2597 or 661-2143, or 1-800-482-5400 ext. 2597
or 2143.
For more information about the WN
virus, visit the Arkansas Department of Health Web site at www.healthyarkansas.com.
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Related
Links:
Pennsylvania's West
Nile Virus Surveillance Program
New
York City Department of Health West Nile Virus Page
New York State Department of Health West Nile Virus Page
Virginia Department of Health West Nile Virus Page
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