Lodi Township, Michigan

Fact Sheet: West Nile Virus (WNV)

What is West Nile Virus?

WNV is a mosquito-borne virus that can cause
encephalitis or meningitis in humans and other animals.
People get West Nile Virus from the bite of a mosquito
that is infected with the virus.

How is it spread?

Mosquitoes become infected with WNV when they feed
on infected birds that carry the virus in their blood.
After 10-14 days the mosquitoes can transmit the virus
to humans and animals while biting to take blood.
Once the virus is in someone’s bloodstream, it
multiplies and may cause illness. You cannot “catch”
the virus from touching someone with the disease.

What is the risk of illness in humans?

The risk of getting West Nile encephalitis/meningitis is
limited to people who are in areas where WNV is
present. The chance you will become seriously ill from
any one mosquito bite is extremely small. The risk of
getting sick is higher for people who are over 50 years
of age, or persons with a weakened immune system.

What are the symptoms?

Most people infected with WNV do not have any
symptoms of illness, but some (1 in 4) may become ill
3-15 days after the bite of an infected mosquito. In a
few cases, mostly among the elderly, death may occur.

Mild illness: Slight fever, headache, body aches, and
sometimes a skin rash & swollen glands.

Serious illness: High fever, severe headache, stiff
neck, mental confusion, convulsions, muscle
weakness and paralysis.

How is it treated?

There is no specific treatment for West Nile
encephalitis/meningitis since antibiotics are not
effective against this virus. Hospitalization is usually
necessary for supportive care, which may include
intravenous fluids, prevention of pneumonia, and
breathing assistance, if necessary.

This fact sheet is for information only and is not meant
to be used for self -diagnosis or as a substitute for
consultation with a health care provider. For more
information, call your health care provider or call
Washtenaw County Public Health at 734-544-6700.

How is West Nile infection prevented?

There is no vaccine for humans available, but there are
many steps that you can take to reduce your risk of
becoming infected:

• Avoid areas where there are large numbers of
mosquitoes and at the times when they are most
active, typically around sunrise and sunset.
• Wear long-sleeved shirts and long pants whenever
you are in mosquito-filled areas.
• Apply insect repellent that contains DEET, picaridin,
or oil of lemon eucalyptus to exposed skin; spray
clothing with repellent because mosquitoes may bite
through thin clothing. Wash repellent off after coming
back indoors. Note: whenever you use an insect
repellent, be sure to read and follow the label
directions for safe use.
• CAUTION: Do not use DEET repellent on children
under 2 months of age.
• Avoid applying repellent to the hands of children
because repellents may irritate the eyes and mouth.
• Repair and maintain window and door screens to
keep mosquitoes out of buildings.
• Limit mosquito breeding sites by draining standing
water in your yard. Empty water from flower
pots/saucers, clogged gutters, wading pools,
swimming pool and patio furniture covers, discarded
tires, pails and buckets and other similar items that
can collect water. Change the water in birdbaths and
horse troughs at least two times a week.
• Cut tall weeds and grass to remove mosquito hiding
and resting areas.
How do we monitor for the disease?

We collect and test dead crows and blue jays for WNV.
We also monitor and test ill humans and horses for
WNV, St. Louis Encephalitis (SLE) and Eastern Equine
Encephalitis (EEE).

Can West Nile Virus infect other animals?

Although the vast majority of infections have been
identified in birds, the Centers for Disease Control have
received reports of WNV in horses, dogs, cats, bats,
chipmunks, skunks, squirrels, domestic rabbits and
raccoons.

Need to report a dead crow or blue jay?

Please call Washtenaw County’s

West Nile Virus Hotline at:

(734) 544-6750
Visit our website at: http://westnile.eWashtenaw.org or the State website at: www.michigan.gov/westnilevirus
Washtenaw County Public Health 555 Towner Ypsilanti, MI 48198 revised 4/06