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What
is West Nile encephalitis? |
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Who
gets West Nile encephalitis? |
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How
is West Nile virus spread? |
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Where
is West Nile virus found? |
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What
are the symptoms of West Nile encephalitis? |
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How
soon after infection do symptoms appear? |
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How
is West Nile encephalitis diagnosed? |
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How
is West Nile encephalitis treated? |
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Is
a woman's pregnancy at risk if she gets West Nile encephalitis? |
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What
proportion of people with severe illness due to West Nile virus die? |
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Is
there a vaccine against West Nile encephalitis? |
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What
can I do to reduce my risk of becoming infected with West Nile virus? |
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What
is West Nile encephalitis? |
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Encephalitis
is an inflammation of the brain and can be caused by viruses and bacteria,
including viruses transmitted by mosquitoes. West Nile encephalitis
is an infection of the brain caused by West Nile virus. |
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Who
gets West Nile encephalitis? |
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People
who live in or traveled to areas where West Nile virus activity has
been identified are at risk of getting West Nile encephalitis; persons
older than 50 years of age have the highest risk of severe disease.
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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How
is West Nile virus spread? |
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West
Nile virus is transmitted when mosquitoes become infected when they
feed on infected birds. Infected mosquitoes can then transmit West
Nile virus to humans and animals. West Nile virus is not transmitted
from person to person. There is no evidence that that a person can
get the virus from handling live or dead infected birds. However,
persons should avoid bare-handed contact when handling any dead animals
and use gloves or double plastic bags. |
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Where
is West Nile virus found? |
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West
Nile virus has been commonly found in humans and birds and other vertebrates
in Africa, Eastern Europe, West Asia, and the Middle East. It had
not previously been documented in the Western Hemisphere until 1999.
The continued expansion of West Nile virus in the United States indicates
that it is permanently established in the Western Hemisphere. West
Nile encephalitis cases occur primarily in the late summer or early
fall. In the southern climates where temperatures are milder, West
Nile virus can be transmitted year round. |
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What
are the symptoms of West Nile encephalitis? |
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Most
infections are mild, and symptoms include fever, headache, and body
aches, occasionally with skin rash and swollen lymph glands. More
severe infection may be marked by headache, high fever, neck stiffness,
stupor, disorientation, coma, tremors, convulsions, muscle weakness,
paralysis, and, rarely, death. Persons older than 50 years of age
have the highest risk of severe disease. |
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How
soon after infection do symptoms appear? |
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Usually,
3 to 15 days. |
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How
is West Nile encephalitis diagnosed? |
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People
who live in or traveled to areas where West Nile virus activity has
been identified are at risk of getting West Nile encephalitis; persons
older than 50 years of age have the highest risk of severe disease.
If you are determined to be at high risk and have symptoms of West
Nile encephalitis, your physician will draw a blood sample and send
it to a commercial or public health laboratory for confirmation. If
you have any of the above symptoms, contact your health care provider. |
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How
is West Nile encephalitis treated? |
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There
is no specific therapy. In more severe cases, intensive supportive
therapy is indicated, often involving hospitalization, intravenous
fluids, airway management, respiratory support (ventilator), prevention
of secondary infections (pneumonia, urinary tract, etc.), and good
nursing care. |
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Is
a woman's pregnancy at risk if she gets West Nile encephalitis? |
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There
is no documented evidence that a pregnancy is at risk due to infection
with West Nile virus. |
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What
proportion of people with severe illness due to West Nile virus die? |
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First,
remember that less than 1% of people who get bitten by an infected
mosquito become infected and get severely ill. Case-fatality rates
range from 3% to 15% among
those with severe illness due to West Nile virus, and are highest
among the elderly. |
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Is
there a vaccine against West Nile encephalitis? |
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No,
but several companies are working towards developing a vaccine. |
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What
can I do to reduce my risk of becoming infected with West Nile virus? |
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- Stay indoors
at dawn, dusk, and in the early evening.
- 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 to
the hands of children.
- Whenever
you use an insecticide or insect repellent, be sure to read and
follow the manufacturer's DIRECTIONS FOR USE, as printed on the
product.
- Note: Vitamin
B and "ultrasonic" devices are NOT effective
in preventing mosquito bites.
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For more information, please visit the CDC web site on West Nile virus
at:
http://www.cdc.gov/ncidod/dvbid/westnile/2001spotlight.htm
and the Metro
St. Louis West Nile Virus Information Center at http://scchealth.org/docs/wnv/wnv_info.html
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