West Nile Virus & Mosquito-Borne Diseases

Mosquito Surveillance Program

The Lake County Health Department actively conducts a multi-faceted mosquito surveillance program in Lake County. Beginning in late-spring and continuing into the autumn, a series of traps are set around the county, including within the Lake County Forest Preserves. At each site a pool, or batch, of mosquitoes is tested weekly for West Nile virus. Areas of stagnant water are also investigated throughout the season for the presence of mosquito larvae, specifically from the Culex mosquito which is the primary carrier of West Nile in Illinois. Finally, the locations of dead birds are monitored to assist in the assessment of potential West Nile virus activity. The Health Department works closely with the municipalities, townships, and the Lake County Forest Preserve District in monitoring the mosquitoes that may pose a public health threat.

Man Looking for Mosquitos

West Nile Virus

West Nile Virus (WNV) was first discovered in the U.S. in New York in 1999. September 2001 marked the first time the virus was identified in Illinois. In 2002, the first human cases of WNV infection in Lake County were confirmed. Since then, there have been a total of 74 human cases in the county with 4 confirmed deaths. The Health Department and Community Health Center continues to work with the Illinois Department of Public Health and other agencies to prevent and minimize this infection in humans.

For more information regarding current and past West Nile Virus activity in Illinois and Lake County, please click here.

County residents may report areas of stagnant water (conducive for mosquito breeding) as well as locations of dead birds, or learn more about the signs and symptoms of West Nile encephalitis by calling the West Nile hotline number: (847) 377-8300.

Zika Virus

Zika virus disease (Zika) is a disease caused by the Zika virus, which is spread to people primarily through the bite of an infected Aedes species mosquito. Anyone who lives in or travels to an area where Zika virus is found and has not already been infected with Zika virus can get it from mosquito bites. The main mosquito that transmits Zika, Aedes aegypti, has not been found in Lake or surrounding counties. The Lake County Health Department and others actively monitor mosquito populations to determine the types of mosquitoes present and if they may be carrying diseases.