Niles's First West Nile Virus Positive Mosquitoes Found, Evanston Leads In Season Totals

NILES, IL — The North Shore Mosquito Abatement District this week confirmed the first West Nile virus positive mosquitoes found in Niles during the 2024 season.

A batch of mosquitoes collected on July 24 from an NSMAD trap in Niles tested positive for the virus on Tuesday, district officials said.

This year, West Nile-positive mosquitoes have also been detected in NSMAD traps across all 12 municipalities in the district, with 111 batches out of the 795 sampled testing positive.

The largest number of tests were conducted on mosquitoes from Evanston, where 21 percent tested positive for the virus, and Skokie, where 19 percent tested positive.

The towns with the lowest percentage of mosquitoes turning up positive for West Nile virus so far this year are Wilmette, Winnetka, Glencoe and Glenview/Golf, all of which had fewer than five West Nile-positive batches.

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For humans, data show the current risk level for West Nile virus infection is low. The vector index measurement of infected Culex mosquitoes stands at 0.4, and anything below 1.0 indicates low risk, district officials said.

West Nile virus infections can cause a range of health effects in humans. Although most cases are asymptomatic, severe symptoms can develop in some cases, potentially leading to serious diseases such as encephalitis or meningitis.

About one in every 150 people who get infected with the virus end up suffering a serious illness, according to the Centers for Disease Control and Prevention,

Residents have been advised residents to take preventive measures to reduce mosquito bites, including using EPA-registered insect repellent, wearing loose-fitting clothing, avoiding outdoor activities during peak mosquito feeding times around dawn and dusk and eliminating standing water on properties, which can serve as mosquito breeding sites.

Historically, the last significant human outbreak of West Nile virus in Cook County occurred in 2012, with 20 reported cases. In the past decade, there have only been 34 cases recorded in the northern Cook County mosquito control district.