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DuPage County Health Department News

Posted on: September 2, 2021

First 2021 Human Case of West Nile Virus in DuPage County

A Culex Pipiens Mosquito

The DuPage County Health Department is reporting the first human case of West Nile virus (WNV) in DuPage County for 2021. An Aurora resident in his 60s became ill in mid-August.

A recent increase in mosquito batches testing positive for the presence of WNV prompted the DuPage County Health Department to encourage county residents to protect themselves from mosquito bites and the risk of contracting WNV.

WNV is transmitted to people by infected mosquitoes. 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).

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 to Dawn: Wear repellent outdoors during these prime times for mosquito activity.

Residents are encouraged to check the Personal Protection Index (PPI) on the Health Department’s website at for the most up-to-date information on WNV activity.

The current level is 2: Moderate Risk, defined as high numbers of infected mosquitoes in most areas, at least one human case. The recommended actions: Drain, Defend, Dusk to Dawn.

The Health Department monitors WNV activity by collecting and testing mosquitoes in traps located throughout the county. The PPI widget will be updated by 3 p.m. each Wednesday throughout the WNV season. These weekly updates will be determined by the Health Department’s vector-borne disease surveillance experts.

WNV activity generally decreases in the fall when cooler temperatures arrive and especially after the first frost of the season.  Additional information and resources on WNV prevention are available at


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