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West Nile Virus

What is West Nile virus infection?

The West Nile virus infection is one that is spread by the bite of infected mosquitoes and usually causes a mild illness, but may also cause encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the brain and spinal cord). This virus is named after the West Nile region of Uganda where the virus was first isolated in 1937. It caused an outbreak in New York in 1999.

Who gets West Nile virus infection?

Anyone can get West Nile virus infection if bitten by an infected mosquito; however, even in areas where transmission of West Nile virus is known to be occurring only a small proportion of mosquitoes are likely to be infected. Even if a person is bitten by an infected mosquito, the chance of developing illness is approximately 1/200. People who are over age 50 are at greater risk of severe illness.

How is West Nile virus spread?

West Nile virus is spread by infected mosquitoes. A mosquito is infected by biting a bird that carries the virus. West Nile virus is not spread from one person to another, or directly from birds to humans.

I've gotten a mosquito bite. Should I be tested for West Nile virus infection?

No, most mosquitoes are not infected with West Nile virus. See a physician if you develop the symptoms below.

What are the symptoms of West Nile virus infection?

The disease may be mild or serious. Mild illness includes fever and muscle aches, swollen lymph glands and sometimes a skin rash. In the elderly, infection may spread to the nervous system or bloodstream and cause sudden fever, intense headache, and stiff neck and confusion, possibly resulting in encephalitis or meningitis. Healthy children and adults may not have any symptoms.

How soon after exposure do symptoms appear?

The symptoms generally appear about 3 to 15 days after exposure but may appear as soon as 1 day after exposure or as late as 7 or more days.

Does past infection with West Nile virus make a person immune?

Yes, a person who gets West Nile virus probably cannot get it again.

What is the treatment for West Nile virus infection? Is there a vaccine for West Nile virus?

There is no specific treatment. Supportive therapy will be used in more severe cases. Most people recover from this illness. There is no vaccine.

How can West Nile virus infection be prevented?

It can be prevented by controlling the mosquito population and protecting against mosquito bites.

  • Wear long, loose and light-colored clothing.
  • If possible, stay indoors when mosquitoes are biting.
  • Use insect repellent products with no more than 35 percent DEET for adults and less than 10 percent for children.
  • Turn over or remove containers in your yard where water collects, such as old tires, potted plant trays, buckets and toys.
  • Eliminate standing water on tarps or flat roofs.
  • Clean out birdbaths and wading pools once a week.
  • Clean roof gutters and downspout screens.

What should hunters do if they harvest a game bird?

Hunters should follow the usual precautions when handling any wild game animal. Here are a few recommended precautions:

  • Do not harvest or handle sick game birds.
  • When cleaning game or handling live or dead birds, use gloves in order to prevent blood to blood contact.
  • Cook game birds until well done.
  • Soak utensils used to prepare game birds in a solution of one part household bleach and 10 parts water for 20 minutes.
  • Most importantly, hunters should avoid mosquitoes as they are the most likely means of acquiring West Nile virus.

Where can I get more information on West Nile virus?

Call your local health department or visit the following web sites: