West Nile Basics
Most mosquitoes are simply annoying. But a small percentage can
carry diseases like West Nile virus. Over the past few years, cases
of West Nile virus have been found in animals, birds, and humans in
all continental states in the United States.
West Nile virus is transmitted to humans from the bite of
mosquitoes that probably picked up the virus after feeding on
infected birds. Pets and other animals can also become infected
with West Nile virus. But you can't get the virus from touching
(or other casual contact with) people or animals.
Most people are unlikely to become seriously ill from West Nile
virus. In fact, someone who does get infected with West Nile virus
may not even know it. That's because most people who do get the
virus usually have few or no symptoms. A small number may have
symptoms like those of the flu, such as fever and body aches.
But they usually get better quickly.
The Centers for Disease Control and Prevention (CDC) believes
that, after becoming infected, a person becomes immune and
won't get sick from the virus again.
A small number of people (less than 1%) who are infected with
West Nile virus do become seriously ill, though. They are
usually people over the age of 50 who are at greater risk of
developing a more severe form of the infection, such as
encephalitis or meningitis.
These more serious forms of infection can cause long-term
illness, brain damage, permanent disability, and - in rare cases -
even death. Symptoms usually begin 2 to 15 days after a person has
been infected.
Severe West Nile virus infection causes symptoms such as:
- high fever
- very stiff neck and back (people are unable to bend their
necks)
- severe headache
- confusion or disorientation
- weak muscles
- convulsions or seizures
People who think they may have symptoms of West Nile virus
should see a doctor right away. Diagnosing the infection early can
help improve a person's chances of recovery.
Tips for Protecting Yourself
Although it's unlikely you'll be infected with West Nile
virus, mosquito bites can still be an itchy nuisance. The CDC
advises people to protect themselves from mosquito bites by using
mosquito repellent, especially at times when mosquitoes are most
active, such as at dusk and dawn.
The CDC recommends mosquito repellents that include one of the
following ingredients:
- DEET (N,N-diethyl-meta-toluamide) - those that contain
between 10% and 30% of DEET are best
- picaridin (KBR 3023)
- oil of lemon eucalyptus (p-menthane 3,8-diol or PMD)
You should reapply these according to the directions on the
product label, which is often not more than once a day. Follow the
manufacturer's instructions for applying the product. Don't
use a sunscreen that includes an insect repellent - sunscreen
should be reapplied frequently but insect repellents should
not.
The Environmental Protection Agency (EPA) offers the following
tips for using insect repellents:
- Don't use insect repellent on skin that is already
covered by clothing.
- Don't spray products directly onto your face (spray the
repellent onto your hands first and then rub it onto your face)
and don't use repellent on your eyes or mouth.
- Wash repellent off once you get back indoors.
- Don't use repellent on areas of the skin that are
irritated or cut.
- Stop using a repellent if it gives you a rash or other skin
reaction, wash it off, and call the doctor.
- Don't let little kids touch the repellent.
You can also take the following precautions to avoid mosquito
bites and West Nile virus:
- Wear long-sleeved shirts and pants that cover your skin. You
can now buy clothing that has been treated with an insect
repellent called permethrin. (This repellent is meant for
clothing, not for applying directly to the skin.) Manufacturers
say that the insect repellent stays on the clothing even after it
has been washed a couple of times.
- Don't hang out near puddles or other pools of standing
water like gutters or wading pools - they are common breeding
grounds for mosquitoes.
- Get rid of mosquito breeding sites by emptying standing water
found in flower pots, buckets, old tires, etc.
- If you find a dead bird, don't touch it with your bare
hands or try to move it. Let your parents know so they can
contact your local health department right away.
Reviewed by:
Larissa Hirsch, MD
Date reviewed: July 2007
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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