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DuPage County Health Department News

Posted on: August 5, 2021

Increase in West Nile Virus Activity in DuPage County Prompts Health Department Advisory

A Mosquito on a Leaf

DuPage County— Reports of increased mosquito pools testing positive for the presence of West Nile virus (WNV) has prompted the DuPage County Health Department (DCHD) to encourage residents to protect themselves from mosquito bites and the risk of contracting WNV.

The Health Department operates a countywide WNV surveillance program, and recent positive reports from mosquitoes trapped in the county are in line with similar reports of WNV activity elsewhere in northeastern Illinois.

Residents are encouraged to check the Personal Protection Index (PPI), at The PPI provides residents with a current snapshot of WNV activity, with risk levels ranging from zero to three, with zero being no activity and three announcing multiple human cases of WNV in DuPage County. The current risk level is one, with “Localized abundance of active mosquitoes, climate conditions favorable for development of virus.” The PPI is updated every Wednesday by Health Department staff during the surveillance season and will change to match the risk level determined for that period.

The weather forecast for the next week includes warmer temperatures, which increases the potential for the increased presence of WNV.

The best way to prevent WNV is to avoid mosquito bites and follow the four Ds of defense:

• Drain: Drain those items that collect standing water around your home, yard, or business. Scrub and refill pet water dishes and bird baths regularly.

• Defend: Use an insect repellent containing DEET when outdoors and reapply according to directions.

• Dress: Wear long pants, long sleeves, and closed-toe shoes when outside to cover the skin.

• Dusk and Dawn: Wear repellent outdoors during these prime times for mosquito activity.

Find more prevention tips and ways to protect yourself, protect your family on the DuPage County Health Department’s “Fight the Bite” page:

Approximately one in five people who are infected with WNV will develop symptoms such as fever, headache, body aches, joint pains, vomiting, diarrhea, or rash. Less than one percent will develop a serious neurologic illness such as encephalitis or meningitis (inflammation of the brain or surrounding tissues).

WNV activity generally decreases in the fall when cooler temperatures arrive and especially after the first frost of the season. More information on WNV activity in Illinois is available at

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