What
Is West Nile Virus?
West Nile virus (WNV) is a potentially serious illness.
Experts believe West Nile Virus is established as a seasonal epidemic
in North America that flares up in the summer and continues
into the fall. This fact sheet contains important information
that can help you recognize and prevent West Nile virus.
What
Are the Symptoms of West Nile Virus?
West Nile Virus affects the central nervous system. Symptoms vary.
-
No
Symptoms in Most People. Approximately 80 percent
of people who are infected with West Nile Virus will not show any
symptoms at all.
-
Mild
Symptoms in Some People. Up to 20 percent of the
people who become infected will display mild symptoms,
including fever, headache, and body aches, nausea, vomiting,
and sometimes swollen lymph glands or a skin rash on
the chest, stomach and back. Symptoms typically last
a few days.
-
Serious Symptoms in a Few People. About one in
150 people infected with West Nile Virus will develop severe illness.
The severe symptoms can include high fever, headache,
neck stiffness, stupor, disorientation, coma, tremors,
convulsions, muscle weakness, vision loss, numbness
and paralysis. These symptoms may last several weeks,
and neurological effects may be permanent.
How
Does West Nile Virus Spread?
-
Infected
Mosquitoes. Generally, West Nile Virus is spread by the bite
of an infected mosquito. Mosquitoes are West Nile Virus carriers
that become infected when they feed on infected birds.
Infected mosquitoes can then spread West Nile Virus to humans and
other animals when they bite.
-
Transfusions,
Transplants, and Mother-to-Child. In a very small
number of cases, West Nile Virus also has spread through blood transfusions,
organ transplants, breastfeeding and even during pregnancy
from mother to baby.
- Not
through touching. West Nile Virus is not spread through casual
contact such as touching or kissing a person with the
virus.
How
Soon Do Infected People Get Sick?
People typically develop symptoms between 3 and 14 days after
they are bitten by the infected mosquito. How
Is West Nile Virus Infection Treated?
There is no specific treatment for West Nile Virus infection. In cases
with mild symptoms, people experience symptoms such as fever
and aches that pass on their own. In more severe cases,
people usually need to go to the hospital where they can
receive supportive treatment including intravenous fluids,
help with breathing and nursing care.
What
Should I Do if I Think I Have West Nile Virus?
Mild West Nile Virus illness improves on its own, and people do not
necessarily need to seek medical attention for this infection.
If you develop symptoms of severe West Nile Virus illness, such as unusually
severe headaches or confusion, seek medical attention immediately.
Severe West Nile Virus illness usually requires hospitalization. Pregnant
women and nursing mothers are encouraged to talk to their
doctor if they develop symptoms that could be West Nile Virus.
What
Is the Risk of Catching West Nile Virus?
For most, risk is low. Less than 1 percent of people
who are bitten by mosquitoes develop any symptoms of the
disease and relatively few mosquitoes actually carry West Nile Virus.
Greater
risk for those outdoors a lot. People who spend a
lot of time outdoors are more likely to be bitten by an
infected mosquito. They should take special care to avoid
mosquito bites.
People
over 50 can get sicker. People over the age of 50
are more likely to develop serious symptoms of West Nile Virus if
they do get sick and should take special care to avoid
mosquito bites.
Risk
through medical procedures is low. The risk of getting
West Nile Virus through blood transfusions and organ transplants is
very small, and should not prevent people who need surgery
from having it. If you have concerns, talk to your doctor
before surgery.
Pregnancy
and nursing do not increase risk of becoming infected
with West Nile Virus.
What
Can I Do to Prevent West Nile Virus?
The easiest and best way to avoid West Nile Virus is to prevent mosquito
bites.
-
When
you are outdoors, use insect repellents containing DEET
(N, N-diethyl-meta-toluamide). Follow the directions
on the package.
-
Many
mosquitoes are most active at dusk and dawn. Consider
staying indoors during these times or use insect repellent
and wear long sleeves and pants. Light-colored clothing
can help you see mosquitoes that land on you.
-
Make
sure you have good screens on your windows and doors
to keep mosquitoes out.
-
Get
rid of mosquito breeding sites by emptying standing
water from flower pots, buckets and barrels. Change
the water in pet dishes and replace the water in bird
baths weekly. Drill drainage holes in tire swings so
water drains out. Keep children's wading pools empty
and on their sides when they aren't being used.
What
Is the CDC Doing About West Nile Virus?
CDC is working with state and local health departments,
the Food and Drug Administration and other government agencies,
as well as private industry, to prepare for and prevent
new cases of West Nile Virus.
Some things CDC is doing include:
-
Coordinating
a nation-wide electronic database where states share
information about West Nile Virus
-
Helping
states develop and carry out improved mosquito prevention
and control programs
-
Developing
better, faster tests to detect and diagnose West Nile Virus
-
Creating
new education tools and programs for the media, the
public, and health professionals
- Opening
new testing laboratories for West Nile Virus
What
Else Should I Know?
If you find a dead bird: Don't handle the body with
your bare hands. Contact your local health department for
instructions on reporting and disposing of the body.
For
more information call the CDC public response hotline
at (888) 246-2675 (English), (888) 246-2857 (Español),
or (866) 874-2646 (TTY)
