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.

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How soon do symptoms appear?

Symptoms can appear between 3 and 15 days after a mosquito bite from an infected mosquito.

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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.

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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.

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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.

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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.

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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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Katie Mullaly
Public Information Officer
Summit County Health Department
6505 N. Landmark Drive
Park City, Utah
Phone: 435-615-3951
Fax: 435-615-3926
kmullaly@lhd.utah.gov

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