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Communicable
Disease Control
Epidemiology
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West
Nile Virus Fact Sheet
(PDF
version) for printing.
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What is West Nile virus?
West Nile virus is a virus commonly found in Africa, West Asia, and the Middle East. It is carried by mosquitoes. West Nile can cause disease in humans, birds, horses, and some other mammals. The virus was found in the U.S. in 1999 and in Utah in August 2003. |
How do people get West Nile virus?
• The most common way is through the bite of an infected mosquito. That’s why prevention is key!
• Very rarely it can be transmitted by:
• Blood transfusion or transplant
• Mother to baby (no baby has died)
• Lab workers through a needle stick (bird sample not human) |
Is there a vaccine available to protect humans from West Nile virus?
No. Currently there is no West Nile virus vaccine available for humans. Many scientists are working on this issue, and there is hope that a vaccine will become available in the next few years.
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Who gets West Nile virus?
Anyone who is bitten by an infected mosquito can get the disease. Persons over the age of 50 or those with poor immune systems are more likely to develop a serious illness if they are infected. |
How does the disease spread?
Wild birds can carry West Nile virus, and the virus is spread to birds by mosquitoes. Infected mosquitoes can give West Nile virus to humans or other animals while biting them. Not all mosquitoes carry West Nile virus. |
Can you get West Nile virus from another person or animal?
No. There is no proof that West Nile virus can be passed between humans or from animals. You get West Nile virus from mosquitoes.
I like to do outdoor activities. Am I at greater risk for West Nile virus?
Outdoor activities are an important part of a healthy lifestyle. Just because West Nile virus is in Utah does not mean that people should stay indoors! You can continue to enjoy the outdoors and easily protect yourself by using mosquito repellent with DEET. |
How can I tell if I was bitten by a mosquito carrying West Nile virus?
Mosquitoes carrying West Nile virus do not look or act differently than any other mosquito. The bite from a mosquito carrying West Nile virus does not look different than any other mosquito bite. You can’t tell when you are bitten by a mosquito that is carrying West Nile virus. |
I have some really large mosquitoes at my house, do they carry West Nile virus?
There are some insects that look just like mosquitoes but are a lot larger. They are not mosquitoes and do not carry West Nile virus. |
Common West Nile virus myths?
Visit this Web site: www.cdc.gov/ncidod/dvbid/westnile/Westnilespotlight2003.htm |
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Horses, Dogs, and Cats |
Can West Nile virus cause illness in horses?
Yes. The West Nile virus can cause serious illness or death
in horses. It is important to fully vaccinate all horses against
West Nile virus. Vaccine will help protect horses against West
Nile virus. For further information, talk to your veterinarian
or call the Utah Department of Agriculture
and Food at 801-538-7161. |
Can West Nile virus cause illness in dogs
or cats?
Dogs and cats can become infected, but they rarely show any
symptoms or unusual behavior. |
Is there a vaccine for cats or dogs?
No. |
Can my I get West Nile virus from my horse,
dog, or cat?
There is no evidence that horses, dogs, or cats will spread
West Nile virus to humans. |
Should a dog or cat infected with West Nile virus be
killed?
No. There is no reason to kill an animal just because it has
been infected with West Nile virus. Full recovery from the infection
is likely. Talk to your veterinarian for more information.
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Can I use insect repellent on my pets?
DEET-based repellents, which are recommended for humans, are
not approved for use on pets (largely because animals tend to
lick their fur.) Talk with your veterinarian for advice about
the right product to use on your pet.
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Human Prevention
and DEET Info |
Protect from Dusk to Dawn
That is when mosquitoes that carry the virus are most active,
so protect yourself and your family and prevent mosquito bites. |
Protect yourself from mosquitoes
Use mosquito repellents that contain DEET* when outdoors from
dusk to dawn. (Follow the label instructions carefully.) For
adults, use repellents containing up to 35% DEET. (Concentrations
higher than 50% do not provide additional protection.) For children
2 months–12 years, use repellents containing up to 10%
DEET. Do not put DEET on children’s hands or feet. For
children under the age of 2 months, do not use DEET. |
Use DEET when doing any outdoor activity – even sitting on your porch in the evening or taking
a morning walk around the block.
* DEET is short for N,N-diethyl-m-toluamide
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Take Cover
For extra protection, wear long-sleeved shirts and long pants
while outdoors. Use mosquito netting when sleeping outdoors
or in an unscreened structure and to protect small babies any
time they are outdoors. |
Reduce mosquitoes around your house
Control mosquitoes – Get rid of all standing water.
· Turn over or remove containers in your yard where water
collects, such as old tires, potted plant trays, buckets, toys,
etc.
· Clean out birdbaths and wading pools at least once
a week.
· Remove standing water on tarps or flat roofs.
· Clean clogged rain gutters and downspouts.
· Clean and stock garden ponds with mosquito-eating fish
or mosquito dunks.
· Recycle old bottles, buckets, and cans.
· Repair leaky faucets and sprinklers.
· Keep swimming pools clean or drain them.
· Make sure screen doors and window screens are in good
condition.
· Keep weeds and tall grass cut short; adult mosquitoes
look for these shady places to rest during the hot daylight
hours.
· Keep window screens on campers, tents, and boats "bug-tight".
· Keep campsites neat. Get rid of mosquito breeding sites.
(Electric "bug zappers" do not help since they usually
attract more mosquitoes than they kill.)
If you can’t get rid of the water (for example,
ornamental ponds, stock tanks, etc.):
· Use “mosquito dunks”. These are small round
disks of Bacillus thurengensis that prevent mosquito larvae
from hatching. They are available in many garden stores and
supply catalogs.
· Use mosquito fish. These are fish known as Gambusia
affinis, and are available from mosquito abatement districts.
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Why should I use a mosquito repellent that contains DEET?
DEET is the most effective insect repellent available. The more
DEET an insect repellent contains, the longer it will protect
you. A higher percentage of DEET does not mean it will protect
you better, just that it will last longer. For example, a product
containing approximately 10% DEET will last about 2 hours, and
24% DEET will last about 5 hours. However, DEET concentrations
higher than 50% do not increase the length of protection. |
Is DEET safe?
Yes, products containing DEET are safe when used according to
the directions. Always follow these steps:
· Use enough repellent to cover exposed skin or clothing.
Don't apply repellent to skin that is under clothing. Heavy
application is not necessary for protection.
· Do not apply repellent to cuts, wounds, or irritated
skin.
· After returning indoors, wash treated skin with soap
and water.
· Do not spray aerosol or pump products in enclosed areas.
· Do not apply aerosol or pump products directly to your
face.
· Spray your hands and then rub them carefully over the
face, avoiding eyes and mouth.
See http://npic.orst.edu/factsheets/DEETgen.pdf for more scientific information. |
Should pregnant or nursing women use DEET?
Women who are pregnant or nursing can use DEET. Be sure to follow
the directions carefully. |
Is there a vaccine for West Nile virus?
There is no vaccine for West Nile virus at this time for humans,
however there is a vaccine for horses. |
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Dead Bird
Information
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What should you do if you find a dead
or ill bird?
A. What kind of bird is it?
Only some kinds of birds are appropriate for testing for WNV. These
birds are ravens, crows, jays, owls, hawks, falcons, and eagles.
You can also check out this link for help in identifying birds: http://www.wildlife.utah.gov/wnv/bird_id.php. If you see a
dead bird that is not one of the above types, carefully throw
the bird in the trash (click here for how to properly dispose of a dead bird).
B. Did lots of birds die at one time?
West Nile virus will not kill a large group of birds in the same area at the same time. If
you see a lot of dead birds in your backyard or in one area, they were probably
poisoned. Check out the Division of Wildlife Resources Web site for
more information.
C. How long has the bird been dead?
Only freshly-dead birds can be tested for WNV. Make sure that
the feathers are shiny, and that there are no maggots or other
signs of rot. If the bird isn't freshly-dead, then carefully
throw the bird in the trash (click here for how to properly dispose of a dead bird).
D. How do you report the dead bird?
At this time the State of Utah is no longer doing dead bird testing for West Nile virus. However, the Salt Lake Valley Health Department is doing a special study on dead birds that are found within Salt Lake County. If you live in Salt Lake County and have a dead bird that fits testing criteria, call the Salt Lake Valley Health Department at 534-4600.
E. What happens after I report the dead
bird?
Collect the dead bird, but do not place it in the garbage can.
Instead, place it in a cool, shaded area. If possible, someone
will come within 24 hours and test the bird for West Nile virus.
If no one comes within 24 hours, discard the bird in an OUTSIDE
garbage container.
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How do I dispose of the dead bird?
· Avoid touching the dead bird with your bare hands.
· Use rubber gloves or put a double plastic bag over
your hand.
· Invert the bag over your hand, grab the bird, wrap
it up, and tie off or seal the bag.
· Throw the double bag and dead bird into an OUTSIDE
garbage container
· Wash your hands thoroughly with soap and water.
· You cannot get West Nile virus from the dead bird. |
Bird Feeder Cleaning Instructions
For routine cleaning: Clean feeders once a week using a bleach
solution - use one part bleach to nine parts water. Rinse feeder
thoroughly with water after cleaning and allow it to dry completely
before refilling it with fresh seed. Remove waste grains from
below feeders. |
If you have had birds die near your feeder:
Use a stronger bleach solution to clean your feeder - one part
bleach to three parts water. Rinse feeder thoroughly with water
after cleaning and allow it to dry completely before refilling
it with fresh seed. Also, remove waste grains from below feeders
and empty water for 7-10 days after an incident where birds
have died near your feeder. |
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Human Symptoms
and Treatment
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What are the symptoms of West Nile virus?
· Most people will not even know they are infected.
· About 20% of infected people develop flu-like symptoms.
This is called West Nile fever. These people may have a fever,
body aches, and possibly a rash.
· Of those that become infected, 1 in 150 will go on
to have the more severe form of the disease. They may have a
stiff neck, and muscle weakness, and they may become confused
or disoriented. Such people may have seizures, go into a coma,
and, in rare occasions, may die. People over the age of 50 are
at highest risk of getting the severe infection. |
How soon do symptoms appear?
Symptoms can appear between 3 and 15 days after a mosquito bite
from an infected mosquito. |
How long do symptoms last?
Symptoms of West Nile fever will generally last a few days,
although even some healthy people report being sick for several
weeks. Symptoms of severe disease (encephalitis or meningitis)
may last several weeks, and some symptoms may become permanent. |
How do I know if I have West Nile virus?
Other illnesses can cause symptoms just like those described
above for West Nile virus. The only way to know if you have
West Nile virus is to see your health care provider. Your health
care provider will need to run laboratory tests to find out
if you have West Nile virus or not. If you are concerned about
your health or about the health of someone in your family, please
contact your health care provider. |
What is the treatment for West Nile virus?
There is no specific treatment for disease caused by West Nile
virus. Antibiotics do not work. There is no vaccine for humans.
You must try and prevent infection. |
If bitten by a mosquito, should I be tested
for West Nile virus?
No. People rarely become sick from a mosquito bite. However,
people with a high fever, severe headache, and muscle weakness
or confusion should see a doctor immediately. People with flu-like
symptoms are likely to recover completely and do not need to
visit a doctor. Even in areas where mosquitoes carry the virus,
very few mosquitoes are infected. The chance that one mosquito
bite will be from an infected mosquito is very small. |
If I have West Nile fever, can it turn
into West Nile Encephalitis?
Usually no. West Nile fever generally goes away after several
days. Some people may develop a brief, West Nile fever-like
illness (early symptoms) before they develop more severe disease,
although it is not known how often this occurs. |
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Virus
Spread to Humans
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How do people get infected with West Nile
virus?
The main way that humans become infected with West Nile virus
is through the bite of an infected mosquito. Mosquitoes become
infected when they feed on infected birds. Humans do not become
infected through direct contact with other humans, horses, birds,
or other animals. |
Can West Nile virus be spread through
blood transfusions?
Yes, but it occurs rarely. Blood banks are now screening blood
to make sure that it does not contain the virus. |
I am pregnant. If I get West Nile virus,
is my baby at risk?
In the United States, one case where a mother gave her baby
West Nile virus was documented during 2002. Experts don’t
yet know how much risk there is to an unborn baby. Pregnant
women should try to avoid infection by wearing protective clothing
and using repellents containing DEET. Pregnant women who become
sick with a high fever and stiff neck should see their doctor
as soon as possible.
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Are hunters who field dress wild game
birds at risk for West Nile virus?
There is no evidence that West Nile virus can be spread directly
from birds or mammals to humans through direct blood contact.
However, hunters are always urged to take proper precautions
and wear rubber gloves when field dressing game. |
Can a person get West Nile virus by eating
infected game birds?
Proper cooking kills the virus. There is most likely no danger
associated with eating well-cooked wild game that might be infected. |
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West Nile virus Cases in Utah from 2003 - 2007 |
2003 |
2004 |
2005 |
2006 |
2007 |
Total |
Average Per Year |
1 |
11 |
54 |
174 |
70* |
310 |
62 |
*2007 data are preliminary and subject to change.
Utah Department
of Health
Office of Epidemiology
May, 2008
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