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Protect Yourself from West Nile Virus

As outdoor activities increase with the warm Colorado weather, remember to protect yourself, and your family, from West Nile Virus.

What is West Nile Virus?

West Nile Virus is a mosquito-borne viral disease that first appeared in the U.S. in 1999 in New York. It has since traveled across the U.S. and is now in Colorado. While most people infected only experience mild flu-like symptoms, West Nile can cause encephalitis or meningitis, and can be fatal.

How is the Virus Spread?

West Nile Virus is spread by the bite of an infected mosquito. The mosquito becomes infected after feeding on a bird that carries the virus. The virus is not spread by person-to-person contact. A human vaccine is being developed, but won’t be available for several years. There is currently a vaccine for horses. Dogs and cats can be infected but rarely become ill and do not spread the virus.

Prevention Tips:

Mosquito season in Colorado is from late spring to mid-September.
Limit time spent outdoors at dawn or dusk, when mosquitoes are most active.
Wear light colored clothing and spray skin and clothes with insect repellent containing DEET. (Use products with 10 percent DEET or less for children.)
Install or repair window screens.
Remove any standing water in flower pots, ditches, garden equipment, birdbaths or wading pools. Mosquitoes lay eggs in still water which hatch in seven to 10 days.
Trim shrubs and don’t over-water lawns.

What are the Symptoms of West Nile Virus?

Symptoms of West Nile usually appear 3 to 14 days after exposure. Most people will have mild flu-like symptoms including fever, headache, body aches, skin rashes or swollen lymph nodes.

The virus can cause encephalitis (swelling of the brain), and/or meningitis (swelling of the brain’s lining). Serious symptoms include high fever, neck stiffness, muscle weakness, tremors, or convulsions. If you suspect symptoms of West Nile, seek medical attention immediately by calling 911, or your physician.

Finding Dead Birds

Early in the season, local health agencies may track reports of dead birds to determine where the virus is active in Colorado. Contact your local health department for more information. Dead birds should not be handled directly, in order to avoid exposure to the virus.

For more information contact the Colorado Department of Public Health and Environment Disease information line at 303-692-2700 or visit



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