SPRINGFIELD – Chronic wasting disease, or CWD, has been detected in Putnam, Marshall, Adams, and Peoria counties, expanding the geographic presence of the disease in free-ranging deer populations in northern Illinois, the Illinois Department of Natural Resources announced today.

Adams County is the first documented case recorded outside of the leading edge of the CWD endemic region.

CWD is an always-fatal neurological disease that affects the long-term health of white-tailed deer in Illinois. First documented in Illinois in 2002 near Roscoe, CWD has been detected in 25 counties across northern Illinois and now as far south as Adams County in west-central Illinois.

In early February 2025, CWD was detected and confirmed through diagnostic testing in Putnam, Marshall, and Adams counties from routine surveillance of hunter-harvested deer. Peoria County was confirmed in a 2-year-old deer exhibiting clinical signs consistent with CWD infection using the same diagnostic testing procedures. Following standard protocol, samples from Adams County underwent genetic testing to ensure genetic matches between submitted tissue samples and source deer.

Affected Illinois counties now include Adams, Boone, Bureau, Carroll, Cook, DeKalb, DuPage, Ford, Grundy, Jo Daviess, Kane, Kankakee, Kendall, Lake, LaSalle, Lee, Livingston, Marshall, McHenry, Ogle, Peoria, Putnam, Stephenson, Will, and Winnebago.

CWD management is important to the overall health of Illinois’ deer herd. A primary goal of ongoing CWD management in Illinois includes lowering prevalence in affected areas to slow the spread of the disease. Those management efforts have kept prevalence low in the state for almost an entire generation of deer hunters.

“Illinois is a national leader in managing and slowing the spread of CWD, and over the past two decades IDNR’s program has served as a model for other states,” said IDNR Director Natalie Phelps Finnie.

While the World Health Organization and the Centers for Disease Control and Prevention have not linked CWD to human transmission, they recommend against eating meat from CWD-positive deer. Hunters are encouraged to have their deer tested and avoid consuming brain, spinal cord, eyes, and other tissues known to harbor the CWD agent.

Go online for additional information about CWD management in Illinois, including updates made to the program in 2024. For more information about these detections or about CWD, contact Chris Jacques, wildlife disease program manager, at [email protected].

IDNR wildlife biologists will be available to discuss current management strategies and answer questions about CWD in public meetings anticipated to occur later this year. Meeting dates and locations will be released at a later date. Landowners, hunters, and interested citizens are encouraged to attend.

Illinois e-News Release

Chronic wasting disease detected in four additional Illinois counties

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