Salt Lake Valley Health Department
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Bureau of Epidemiology
Bureau of Epidemiology
610 South 200 East #218
Salt Lake City, Utah 84111
385-468-4222
West Nile Virus Fact Sheet
What is West Nile virus?
West Nile virus (WNV) infection is a mosquito-borne illness that can be very serious and, in some cases, cause death. West Nile virus was first found in the United States in 1999 in Queens, New York.
Stats about WNV in Salt Lake County
What are the symptoms of West Nile virus infection?
A few people will have serious illness. About one in 150 people infected with WNV will develop severe illness. These symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness, and paralysis. These symptoms can last several weeks to months, and neurological effects may be permanent.
Some people will have milder illness. Up to 20 percent of the people who become infected will display symptoms that may include fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands. They may also develop a skin rash on the chest, stomach or back. Some people are sick for a few days, but even previously healthy persons have been sick for several weeks with infection.
Most people will have no symptoms at all. Approximately 80 percent of people infected with WNV will not have any signs or symptoms, but there is no way to know in advance if you will develop severe illness or not.
How does West Nile virus spread?
- Infected mosquitoes- mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread WNV to humans when they bite.
- Transfusions and Transplants- WNV also has been spread through blood transfusions and organ transplants when the donor was infected with WNV.
- Mother-to-Child- Rarely, infants have acquired illness from the mother during pregnancy or from breastfeeding.
- Not through touching. WNV is not spread from person to person.
What is the treatment for West Nile virus infection?
There is no specific treatment for WNV infection. People with mild infections recover on their own. People with severe symptoms require hospitalization. Some people who develop severe illness may die from the infection.
How soon do infected people get sick?
People usually develop symptoms within 3 to 14 days after they are bitten by an infected mosquito.
Who is at risk of getting severe West Nile infection?
People who are over the age of 50, are immunocompromised, or have diabetes are at higher risk of having serious symptoms and illness from WNV. These individuals should be careful to avoid mosquito bites.
What can I do to protect myself from West Nile virus infection?
- Mosquitoes that transmit disease bite from dusk to dawn. When you are outdoors during these hours, wear long pants, a long sleeved shirt and socks. To avoid mosquito bites.
- Use a repellent with DEET, permethrin, picaridin, IR3535 or oil of lemon eucalyptus according to package directions.
CDC Repellent Information. - Regularly get rid of standing water in your yard such as old tires, potted plant trays, pet dishes, toys, buckets, etc.
- Keep roof gutters clear of debris
- Clean swimming pools often or drain them
- Clean and stock garden ponds with mosquito-eating fish or mosquito dunks
- Make sure screen doors and window screens are in good condition so that mosquitoes cannot get indoors
- Keep weeds and tall grass cut short; adult mosquitoes look for these shady places to rest during the hot daylight hours.
What should I do if I think I have a WNV infection?
If you develop sign and symptoms of WNV infection you should see your doctor. If the signs and symptoms are severe, such as unusually severe headaches or confusion, seek medical attention immediately. Severe WNV illness usually requires hospitalization. Pregnant women and nursing mothers are especially encouraged to talk to their doctor if they develop symptoms that could be WNV.