News of an epidemic of West Nile virus in the U.S. probably has you
on high alert. But don't let worries about mosquitoes keep you and your
family from enjoying the outdoors. The chances of anyone in your family
becoming sick with the West Nile virus are extremely low, no matter what
part of the country you live in.
Taking precautions against mosquito bites can help lessen the fear,
but so can learning about the virus. Here's what you need to know:
- Less than 1% of mosquitoes in any area where carrier mosquitoes have been found are actually infected with West Nile virus.
- Fewer than 1% of people who are bitten and infected with West Nile virus will become seriously ill.
- Kids and adults younger than 50 are less likely to become sick from the infection if they do get it.
- Fewer than 1% of people who get West Nile virus develop severe illness.
About West Nile Virus
West Nile is a virus that is spread by the Culex species of
mosquito. Mosquitoes become infected by feeding on infected birds, and
then transmit the virus to humans and animals through bites. It is not
transmitted from person to person, animal to animal, or animal to
person.
Once in the bloodstream, the virus multiplies and spreads. If the
virus reaches the brain, the result is encephalitis - an inflammation of
the brain that can affect the entire nervous system. Although rare,
encephalitis is the most serious complication associated with the virus;
those at greatest risk are people older than 50.
West Nile virus has been around a long time. It is commonly found in
Africa, Eastern Europe, West Asia, and the Middle East, but until 1999
had not been found in the Western Hemisphere. It's unknown how the West
Nile virus entered the United States, but experts say it's most similar
to the strains found in the Middle East.
Since that time, the Centers for Disease Control and Prevention (CDC)
has verified reports of West Nile virus infection in birds, mosquitoes,
or humans throughout most of the country. There is no evidence to
suggest that West Nile virus is transmitted by ticks, birds, or any
other insect besides mosquitoes. It is possible for your pet to become
infected, but your pet cannot transmit the virus to you.
Although the risk of infection is very low due to routine screening
of donated blood, the infection has been transmitted through blood
transfusion in a few cases. There have also been a few reports of
fetuses of pregnant women becoming infected when the mother developed
West Nile virus infection.
Signs and Symptoms
Most of the time, a person bitten by an infected mosquito does not
get sick. Most people who do get sick from the virus become only mildly
ill. A person may experience flu-like symptoms such as fever, headache,
body aches, and sometimes skin rash and swollen glands.
About 1 person in 150 infected with the West Nile virus will get
severely ill. Severe infection can result in encephalitis; symptoms can
include severe headache, high fever, neck stiffness, disorientation, and
sometimes convulsions. Although very rare, severe West Nile infection
in healthy, younger people can be fatal, but the elderly are at greatest
risk for severe complications.
The incubation period for West Nile virus is usually 3 to 14 days. In
the northern United States, infections occur mainly in the summer and
early fall, but in the warmer southern regions, the virus can be
transmitted all year.
Prevention
What can you do to protect yourself from West Nile virus? The CDC recommends these precautions:
- Try to stay indoors at dusk and dawn, when mosquitoes are most active.
- Use screens on doors and windows to keep mosquitoes from entering your home. You should also repair broken or damaged screens.
- Wear long-sleeved shirts and long pants whenever you are outdoors.
- Because mosquitoes can bite through thin clothing, spray your
clothes with insect repellents containing permethrin or DEET (look for
N,N-diethyl-meta-toluamide). For children, choose a repellent that
contains no more than a 30% concentration of DEET; in higher
concentrations, the chemical, which is absorbed through the skin, can be
toxic. Be sure to read and follow the directions on the label. Repellents with
picaridin and oil of lemon eucalyptus also offer long-term protection.
- If you apply insect repellent to exposed skin, do so sparingly. Do
not apply repellent to your child's hands, as it can cause irritation if
transmitted to the eyes or mouth.
- Don't rely on vitamin B or ultrasonic devices to prevent mosquito bites - neither has been proven effective.
- Be sure to eliminate mosquito-breeding areas around your home by
removing standing water from gutters, old tires, wading pools, tarps,
potted plants, and other outside buckets and pails. Also, be sure the
water in pet dishes and birdbaths is changed regularly.
Diagnosis
If anyone in your family has any symptoms of West Nile virus, contact
your doctor right away. The doctor will determine your risk based on
where you live or whether you've traveled to an area where infected
mosquitoes have been found. If the doctor suspects West Nile virus, a
blood sample will be drawn and sent to a lab to be tested for infection.
Treatment
There is no specific treatment for West Nile encephalitis other than
supportive therapy (such as hospitalization, intravenous fluids, and
respiratory support) for severe cases. Antibiotics will not work because
a virus, not bacteria, causes West Nile disease. No vaccine for the
virus is currently available.
The public has played a large role in helping track West Nile
infection patterns by reporting the appearance of dead birds to the
authorities. Continued surveillance is essential to keep the virus in
check.
If you see a dead bird in your area, do not handle the body with your
bare hands. Instead, contact your state or local health department
immediately. Once virus activity is discovered in an area - even before
the first case of human disease is reported - mosquito control measures
can go into effect, including the widespread spraying of pesticides
against adult mosquitoes and larvae.
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