Illinois Chronic Wasting Disease Update: Spring 2026

This year, chronic wasting disease (CWD) was detected in the state’s deer herd in three new counties: Effingham, Scott, and Stark. Effingham and Scott join Adams County as the first documented cases outside of the leading edge of the northern Illinois CWD endemic region, resulting in 28 counties where the disease has been detected.

These recent detections are clear indicators that the disease has expanded beyond IDNR’s capacity to manage it effectively through a long-term sharpshooting program. After a valiant 23-year effort by biologists to control CWD in Illinois’ deer herd, IDNR will suspend its targeted culling (sharpshooting).

Illinois’ free-ranging deer herd is an incredibly valuable and cherished public resource and the heart of outdoor culture in the state. Protecting the health of the herd has always been the goal of IDNR’s CWD management program. CWD is fatal in every case and can impact white-tailed deer populations.

The disease was first detected in Illinois deer in 2002 when it was discovered in Boone County. Since 2003, IDNR has employed active CWD management through sharpshooting, coupled with liberalized hunting opportunities and baiting restrictions, to lower prevalence in affected areas and slow the spread of the disease.

The program IDNR developed earned national recognition for its ability to slow the spread. These efforts kept CWD prevalence low in Illinois – below 2% – and confined to the northern part of the state for almost an entire generation of deer hunters

However, during the past seven years, Illinois saw a rapid increase in prevalence rates – up to 9.2% in 2025 – and a continued spread southward into central Illinois. The expanded geographic distribution, along with growing fatigue among cooperating landowners and the public, prompted IDNR to suspend its targeted culling efforts.

CWD can be transmitted between deer and is caused by misfolded proteins called a prion, which can damage brain and nerve tissue in deer, elk, moose, and other members of the Cervid family.

CWD has been documented in 36 states and five Canadian provinces. Illinois joined other fish and wildlife agencies, the federal government, and universities in providing research and knowledge about the disease. Through management efforts and collaboration, experts have learned a great deal about the disease.

All available information indicates CWD prevalence will continue to increase and the disease will spread into new areas. White-tailed deer population declines and age-structure impacts have been documented in areas of high CWD prevalence. A relatively small increase in harvest and removal of deer at the local level can help keep CWD prevalence low.

Although 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.

IDNR staff will continue to monitor CWD within the state, provide sampling opportunities for hunters, and engage with the public to help address management of the disease.

IDNR also will host public open houses with hunters and landowners around the state this summer to update them on the status of the disease in Illinois and encourage continued vigilance and testing when harvesting deer.

Illinois hunters and landowners have been valuable partners from the beginning and will continue to play a vital role in CWD monitoring and management by:

• Continuing to hunt and harvest deer
• Encouraging deer hunting on private property
• Increasing the number of deer taken – particularly antlerless deer – in and around areas with CWD
• Having harvested deer tested for CWD

The IDNR thanks the many partners and organizations that continue to help battle this disease: the cooperating hunters and landowners, US Fish and Wildlife Service, USDA Wildlife Services, the Illinois Natural History Survey, Wildlife Veterinary Epidemiology Laboratory, the SIU Cooperative Research Laboratory, and the Illinois Department of Agriculture.