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What is West Nile Virus
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What kinds of birds carry the West
Nile virus?
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Where did West Nile virus come from?
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What are the symptoms of West Nile
virus infection?
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How soon after exposure do symptoms
appear and who is at highest risk for serious illness?
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What if I am pregnant?
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How do people get West Nile virus?
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If I live in an area where birds or
mosquitoes with West Nile virus have been reported and a mosquito
bites me, am I likely to get sick?
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Can I get West Nile virus directly
from birds?
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How can I discard a dead bird?
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What will happen if my dog or cat
eats an infected bird?
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How can I report a sighting of dead
bird(s) in my area?
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Can West Nile virus be spread from
person-to-person?
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How can I protect myself and my family
from West Nile virus?
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What should hunters do to protect
themselves against West Nile virus?
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How is West Nile virus diagnosed?
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What is the treatment?
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Is there a West Nile virus vaccine
for humans?
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Additional Sources of Information
Regarding West Nile Virus
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What is West Nile Virus?
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The West Nile virus is transmitted by mosquitoes
to birds, various animals, and humans. Most persons infected with
this virus show no symptoms, although occasional infections can
result in serious illness and even death.
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What kinds of birds carry the
West Nile virus?
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Any wild or domestic bird can be infected with this
virus, but some species are particularly susceptible to disease
and death from this infection. These species include crows, blue
jays, and birds of prey such as hawks, owls, and eagles. However,
based on our current understanding of this virus, it appears that
the only significant risk to humans is through the bite of an infective
mosquito (see “How do people get West Nile
virus?” below).
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Where did West Nile virus come
from?
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West Nile virus has been commonly found in humans,
birds, and other animals in Africa, Eastern Europe, Western Asia,
and the Middle East, but until 1999 had not previously been documented
in the Western Hemisphere. The U.S. viral strain is most closely
related genetically to strains found in the Middle East.
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What are the symptoms of West
Nile virus infection?
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Most people infected with this virus do not have
any symptoms. Some people experience a mild illness characterized
by slight fever, headache, body aches, skin rash, and swollen lymph
nodes. More severe illness can include encephalitis (inflammation
of the brain) and is marked by a rapid onset of a high fever, head
and body aches, neck stiffness, muscle weakness, disorientation,
coma, tremors, convulsions, and in the most severe cases, death.
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How soon after exposure do symptoms
appear and who is at highest risk for serious illness?
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Symptoms usually appear 3 to 15 days after exposure.
Persons who are at highest risk for serious illness are persons
over the age of 50. Healthy children and adults are at very low
risk for infection.
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What if I am pregnant?
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There is no evidence that pregnant women are at increased
risk due to West Nile virus infection.
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How do people get West Nile virus?
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The West Nile virus, like most mosquitoborne viruses,
is found in wild and domestic birds. When a mosquito feeds on an
infected bird, it can pick up the virus and transmit it to other,
noninfected birds. Occasionally, infective mosquitoes will feed
on mammals such as horses, dogs, cats, and humans, and transmit
the virus to them.
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If I live in an area where birds
or mosquitoes with West Nile virus have been reported and a mosquito
bites me, am I likely to get sick?
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No, even in areas where mosquitoes do carry the virus,
very few mosquitoes—much less than 1%—are infected. If
the mosquito is infected, less than 1% of people who get bitten
and become infected will get severely ill. The chances you will
become severely ill from any one mosquito bite are extremely small.
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Can I get West Nile virus directly
from birds?
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There is no evidence that a person can get the virus
from handling live or dead infected birds. However, persons should
avoid barehanded contact when handling any dead animals and use
gloves or double plastic bags to discard dead animals.
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How can I discard a dead bird?
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Place the dead bird in double plastic bags (using
gloves or the plastic bags to prevent skin contact) and discard
in a garbage can. Birds can also be buried or incinerated, taking
care to prevent direct skin contact with the birds.
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What will happen if my dog or
cat eats an infected bird?
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There is no evidence that West Nile virus infection
can be acquired by ingestion. Very few dogs and cats have been found
to be infected with the West Nile virus even in those parts of the
country where infected mosquitoes are found.
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How can I report a sighting of
dead bird(s) in my area?
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Contact your local or state health department if
you observe dead birds, particularly crows and blue jays. Health
officials will determine whether the event should be investigated
and whether bird specimens should be submitted to a laboratory for
testing.
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Can West Nile virus be spread
from person-to-person?
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West Nile virus infection is not transmitted
from person to person. For example, you cannot get West Nile virus
from touching or kissing a person who has the disease, or from a
health care worker who has treated someone with the disease.
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How can I protect myself and
my family from West Nile virus?
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It is not necessary to limit any outdoor activities.
However, you can and should try to reduce your risk of being bitten
by mosquitoes. Mosquitoes are most active at dawn and dusk. Reducing
the mosquito population around your home and property can be accomplished
by eliminating standing water:
- Dispose of tin cans, plastic containers, ceramic
pots or similar water-holding containers.
- Remove all discarded tires on your property. Used
tires are very significant mosquito breeding sites.
- Drill holes in the bottoms of recycling containers
that are kept outdoors.
- Make sure roof gutters drain properly, and clean
clogged gutters in the spring and fall.
- Turn over plastic wading pools and wheelbarrows
when not in use.
- Change the water in birdbaths at least weekly.
- Clean vegetation and debris from edges of ponds.
- Clean and chlorinate swimming pools, outdoor saunas,
and hot tubs.
- Drain water from pool covers.
- Use landscaping to eliminate standing water that
collects on your property.
In addition to reducing standing water in your yard,
make sure all windows and doors have screens, and that all screens
are in good repair. If West Nile virus is found in your area:
- Wear long-sleeved shirts and long pants whenever
you are outdoors.
- Spray clothing with repellents containing permethrin
or DEET since mosquitoes may bite through thin clothing.
- Apply insect repellent sparingly to exposed skin.
An effective repellent will contain 35% DEET (N,N-diethyl-meta-toluamide).
DEET in high concentrations (greater than 35%) provides no additional
protection. Repellents may irritate the eyes and mouth, so avoid
applying repellent directly to the face and hands of children.
No definitive studies exist in the scientific literature about
what concentration of DEET is safe for children and pregnant women.
The American Academy of Pediatrics has recommended that a cautious
approach is to use products with a low concentration of DEET,
10% or less, on children aged 2 - 12. Whenever you use an insecticide
or insect repellent, be sure to read and follow the manufacturer's
DIRECTIONS FOR USE.
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What should hunters do to protect
themselves against West Nile virus?
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Hunters should follow the usual precautions when
handling wild animals. They should wear gloves when handling and
cleaning animals to prevent blood exposure to bare hands and meat
should be cooked thoroughly. If hunters anticipate being exposed
to mosquitoes, they should apply insect repellents to clothing and
skin according to label instructions.
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How is West Nile virus diagnosed?
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If you or your family members develop symptoms such
as high fever, confusion, muscle weakness, and severe headache,
you should see your health care provider immediately. Your health
care provider will assess your risk for West Nile virus infection.
If you are determined to be at high risk, your provider will draw
a blood sample and send it to a laboratory for confirmation.
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What is the treatment?
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There is no specific treatment for viral infections,
other than to treat the symptoms and provide supportive care. In
more severe cases, intensive supportive therapy is indicated, often
involving hospitalization, intravenous fluids and nutrition, respiratory
support, prevention of secondary infections, and good nursing care.
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Is there a West Nile virus vaccine
for humans?
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No, but several companies are working towards developing
a vaccine.
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Additional Sources of Information
Regarding West Nile Virus
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Missouri
Department of Health and Senior Services web site
Centers
for Disease Control (CDC) and Prevention web site
CDC Hotline: live person!
Monday – Friday, 8 am – 11 pm ET; Saturday, Sunday, 10
am – 8 pm ET
1-888-246-2675 (English), 1-888-246-2857 (Spanish).
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