West Nile Virus Prevention

The best way to prevent West Nile encephalitis and other mosquito-borne illnesses is to reduce the number of mosquitoes around your home and neighborhood and to take personal precautions to avoid mosquito bites.Some of the steps to reducing your exposure to mosquito bites include:

• Throw away all trash that can hold water, such as tin cans, jars, and old tires.
• Clean out rain gutters; be certain no water remains on flat roofs after rains.
• Change water in birdbaths at least once a week.
• Clean out and fill in tree holes with concrete.
• Stock decorative ponds with goldfish or mosquito-fish.
• Empty children’s wading pools weekly.
• Fill in or drain low areas in your yard.
• Empty your pet’s water bowl daily.
• Keep weeds and tall grass cut short; adult mosquitoes look for these shady places to rest during the hot daylight hours.

The Health Department offers other preventative measures that you can protect yourself from mosquito bites:

• Avoid places and times when mosquitoes bite. Generally, the peak biting periods occur just before and after sunset and again just before dawn. Each species, however, has its own peak period of biting. Tree-hole and Asian tiger mosquitoes, for example, feed during daylight hours in or near shaded or wooded areas.
• Be sure door and window screens are tight-fitting and in good repair.
• Wear appropriate clothing. Long-sleeved tops and long pants made of tightly woven materials keep mosquitoes away from the skin. Be sure, too, that your clothing is light colored. Keep trouser legs tucked into boots or socks.
• Use mosquito netting when sleeping outdoors or in an unscreened tent.
• Check to see that your mosquito repellent contains DEET, a chemical commonly found in these products. Generally, repellents with about 30% DEET work best for adults; use lower concentrations for children. When outdoors, apply repellent sparingly to exposed skin or clothing, as indicated on the product’s label.

What Type Of Mosquitoes Are Found In Illinois?

Two different kinds of mosquitoes plague Illinois. Floodwater (temporary pool) mosquitoes lay their eggs in low lying areas that will be flooded later. Under normal summer temperatures, large numbers of biting mosquitoes will emerge a couple of weeks after heavy rains and can be a major nuisance for several weeks.

Disease-carrying mosquitoes lay their eggs in anything that hold stagnant water such as, old tires, clogged gutters, cans, ditches, sewage treatment plant ponds, unkept swimming pools and birdbaths. Eggs will hatch within a few days.

In Illinois, the most common human illness carried by mosquitoes is encephalitis. Encephalitis is an inflammation of the brain caused by a virus. Severe symptoms include rapid onset of severe headaches, high fever, and mental disturbances such as confusion, irritability, tremors, stupor, and coma. Cases sometimes end in death or with survivors suffering permanent physical and mental disabilities.

Mosquitoes do not carry all types of encephalitis virus, but they do carry at least three that can cause illness. The Culex mosquito, which bites from dusk till dawn, is a vector of St. Louis encephalitis and West Nile virus; it becomes infected by feeding on birds that carry these viruses. The tree-hole mosquito, which bites during the day, is the main vector of California (LaCrosse) encephalitis in Illinois.