Is West Nile Virus?
West Nile virus (WNV) is a potentially serious illness.
Experts believe WNV 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.
Can I Do to Prevent WNV?
The easiest and best way to avoid WNV is to prevent mosquito bites.
mosquitoes are most active at dusk and dawn. Be sure
to use insect repellent and wear long sleeves and
pants at these times or consider staying indoors during
sure you have good screens on your windows and
doors to keep mosquitoes out.
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 holes in tire swings so
water drains out. Keep children's wading pools
empty and on their sides when they aren't being
Are the Symptoms of WNV?
Serious Symptoms in a Few People. About one in
150 people infected with WNV 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.
Symptoms in Some People. Up to 20 percent of the people
who become infected have symptoms such as fever, headache,
and body aches, nausea, vomiting, and sometimes swollen
lymph glands or a skin rash on the chest, stomach and
back. Symptoms can last for as short as a few days, though
even healthy people have become sick for several weeks.
Does West Nile Virus Spread?
Mosquitoes. Most often, WNV is spread by the bite
of an infected mosquito. Mosquitoes become infected
when they feed on infected birds. Infected mosquitoes
can then spread WNV to humans and other animals when
Transplants, and Mother-to-Child. In a very small
number of cases, WNV also has been spread through blood
transfusions, organ transplants, breastfeeding and even
during pregnancy from mother to baby.
through touching. WNV is not spread through casual
contact such as touching or kissing a person with the
Soon Do Infected People Get Sick?
People typically develop symptoms between 3 and 14 days after
they are bitten by the infected mosquito.
Is WNV Infection Treated?
There is no specific treatment for WNV infection. In cases
with milder symptoms, people experience symptoms such as
fever and aches that pass on their own, although even healthy
people have become sick for several weeks. 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.
Should I Do if I Think I Have WNV?
Milder WNV illness improves on its own, and people do not
necessarily need to seek medical attention for this infection
though they may choose to do so. If you develop symptoms
of severe WNV illness, such as unusually severe headaches
or confusion, seek medical attention immediately. Severe
WNV illness usually requires hospitalization. Pregnant women
and nursing mothers are encouraged to talk to their doctor
if they develop symptoms that could be WNV.
Is the Risk of Getting Sick from WNV?
over 50 at higher risk to get severe illness. People
over the age of 50 are more likely to develop serious
symptoms of WNV if they do get sick and should take special
care to avoid mosquito bites.
outside means you're at risk. The more time you're
outdoors, the more time you could be bitten by an infected
mosquito. Pay attention to avoiding mosquito bites if
you spend a lot of time outside, either working or playing.
through medical procedures is very low. All donated
blood is checked for WNV before being used. The risk of
getting WNV 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
and nursing do not increase risk of becoming infected
with WNV. The risk that WNV may
present to a fetus or an infant infected through breastmilk
is still being evaluated. Talk with your care provider
if you have concerns.
Is the CDC Doing About WNV?
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 WNV.
Some things CDC is doing include:
a nation-wide electronic database where states share
information about WNV
states develop and carry out improved mosquito prevention
and control programs
better, faster tests to detect and diagnose WNV
new education tools and programs for the media, the
public, and health professionals
new testing laboratories for WNV
with partners on the development of vaccines
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.
may tell you to dispose of the bird after they log your
more information call the CDC public response hotline
at (888) 246-2675 (English), (888) 246-2857 (Español),
or (866) 874-2646 (TTY)