DuPage County health officials said the first mosquito batches of the 2026 season tested positive for West Nile virus, prompting residents to take prevention steps. The county said the positive pools were found in Roselle, Glendale Heights and Wheaton, and no human cases had been reported at the time of the release.
DuPage County health officials said the first mosquito batches of the 2026 season have tested positive for West Nile virus, marking the county's first confirmed mosquito detections of the year.
The DuPage County Health Department said the positive pools were collected in Roselle, Glendale Heights and Wheaton. Officials said no human West Nile cases had been reported in the county at the time of the announcement.
The county said the first positive mosquito batches were identified on May 12, 2026. CBS Chicago and NBC Chicago later reported the warning on May 18.
Health officials urged residents to reduce standing water around homes, use insect repellent and take other standard precautions to limit exposure as mosquito activity increases.
West Nile virus is commonly tracked through mosquito surveillance in Illinois each season, and county health departments typically issue warnings once positive pools are found.
Officials also asked residents to report stagnant water concerns that may help mosquitoes breed. Further updates would depend on whether additional positive mosquito batches or any human cases are reported later in the season.
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