West Nile virus (WNV) 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 reported infant deaths)
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 continue to work on vaccine development. It is hopeful that a vaccine will become available in the next few years.
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 spread West Nile virus to humans or other animals through biting. 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 spread between humans or from animals. West Nile virus is spread from infected 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?
You can’t tell when you are bitten by a mosquito that is 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.
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 much larger. They are not mosquitoes and do not carry West Nile virus.
Human Prevention and DEET information
Protect from dusk to dawn
That is when mosquitoes that carry the virus are most active. Protect yourself and your family during these times to prevent mosquito bites.
Protect yourself from mosquitoes
Use mosquito repellents that contain DEET (N, N-diethyl-m-toluamide) when outdoors from dusk to dawn. Follow the label instructions carefully. For adults and children over two months of age, use repellents containing up to 30% DEET. Concentrations higher than 50% do not provide additional protection. Do not use DEET on children’s hands or feet.
Use DEET when outdoors
Use it even sitting on your porch in the evening or taking a morning walk around the block.
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.
Should pregnant or nursing women use DEET?
Women who are pregnant or nursing can use DEET. Be sure to follow the directions carefully.
For extra protection, wear long-sleeved shirts and long pants while outdoors. Use mosquito netting when sleeping outdoors or in an unscreened structure. 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 (ornamental ponds, stock tanks, etc.):
Use “mosquito dunks.” These are small round disks containing Bacillus thurengensis that prevent mosquito larvae from hatching. They are available in many garden stores and
Use mosquito fish. These are fish known as Gambusia affinis, and are available from mosquito abatement districts.
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 two hours, and 24% DEET will last about five hours. However, DEET concentrations higher than 50% do not increase the length of protection.