DuPage County reports first mosquitoes carrying West Nile virus for 2026

The DuPage County Health Department has confirmed its first positive tests for West Nile virus in pools of mosquitoes this year.

The first pools of West Nile-positive mosquitoes were found in Roselle, Glendale Heights, and Wheaton, on Tuesday, May 12. County health officials advise residents to prevent mosquito bites and reduce the risk of getting the virus.

Statewide in Illinois, three counties have reported West Nile-positive mosquitoes. In addition to DuPage, Cook County has reported eight batches of mosquitoes that have tested positive for mosquitoes, while downstate Madison County in the Metro East region opposite St. Louis has reported one, according to the Illinois Department of Public Health.

There have been no human cases so far this year.

The DuPage County Health Department and other public health departments have come up with three R's for West Nile prevention — and words that require dropping a letter to start with an R such as "'riting" and "'rithmetic" are not among them.

The department advises that people:

• Reduce your exposure and ethe number of mosquitoes by removing outdoor containers that can hold water.
• Repel mosquitoes with insect repellent.
• Report stagnant water seen longer than a week or other concerns regarding West Nile to health officials. DuPage County residents should use the county health department website.

The public is also advised to wearing loose-fitting clothing, and, if possible, avoid peak mosquito feeding times, typically around dusk and dawn. 

West Nile virus is spread to humans through bites from mosquitoes that have contracted the virus by feeding on infected birds.

Most cases of West Nile virus in humans are either mild, or show no symptoms, meaning many cases go unreported. Eight out of 10 people infected do not develop symptoms, according to the Centers for Disease Control and Prevention.

Individuals over the age of 60, and those with certain medical conditions, such as cancer, diabetes, hypertension, kidney disease, and organ transplants are at greater risk for serious illness and rarely may progress to permanent neurological damage, coma, and death. Anyone who experiences symptoms that cause concern should contact their doctor.

The worst year in Illinois for West Nile was 2002, when there were 884 cases across the state, and 67 deaths — 42 of them in Cook County.