Illinois ends chronic wasting disease deer culls after 20 years

The Night the Deer Stopped Coming

The cornfield near Lowden-Miller State Forest was quiet. Daniel Skinner, the forest wildlife manager for the Illinois Department of Natural Resources, had poured a pile of dried corn onto the ground at dusk, a practice repeated across the state for years. His .308 Remington rifle, equipped with a thermal scope, rested against his shoulder as he settled into a camouflaged blind. Eight hours later, the tally was one deer—down from ten the previous year. By midnight, the team called it off.

The decline in deer encounters during culls suggested shifts in population dynamics or movement patterns, though the exact causes remained unclear. Skinner noted the unique challenges posed by the disease, which officials have described as particularly difficult to manage. The decision to halt targeted culls in April reflected a reassessment of the strategy’s effectiveness after years of effort.

Chronic wasting disease, caused by misfolded proteins called prions, does not behave like a typical pathogen. It lingers in soil and water, transmitted through saliva, urine, and feces. It can take 18 months to manifest symptoms—emaciation, stumbling, a vacant stare—by which point the animal is already a potential source of transmission. Illinois had tested thousands of deer since 2003, with no confirmed cases detected. The absence of positive results did not rule out the presence of the disease but highlighted the limitations of existing detection methods.

The $5 Samples That Went Nowhere

In Connecticut, Andrew Labonte, a wildlife biologist with the Department of Energy and Environmental Protection, has spent two decades collecting samples from taxidermists. The process is straightforward: hunters bring in deer heads for mounting, unaware that the brain stem and lymph nodes are sent to a lab in Pennsylvania. The state pays a small fee per sample. Labonte noted that most hunters do not realize their deer are being tested for chronic wasting disease.

The system has yielded thousands of negative tests since 2003. However, the disease’s long incubation period means infected deer can appear healthy for years. While Connecticut has not confirmed any cases, the disease has been detected in neighboring states like New York and Pennsylvania. Labonte’s team tests a portion of the state’s deer population annually, raising questions about whether current testing can detect the disease before it becomes widespread.

The samples, like the Illinois culls, were part of a broader surveillance effort to track the disease’s spread. The approach relied on monitoring rather than eradication, a strategy that has faced scrutiny as the disease continues to expand. Labonte acknowledged the uncertainty surrounding the disease’s arrival in Connecticut, emphasizing the importance of vigilance in states where it has not yet been detected.

A Disease That Defies the Playbook

Chronic wasting disease does not follow the rules of conventional pathogens. Prions, the misfolded proteins that drive it, are not alive and cannot be neutralized with heat, disinfectants, or antibiotics. They persist in the environment for years, binding to soil and vegetation. When healthy deer graze in contaminated areas, the cycle of transmission continues.

The disease’s persistence has led wildlife managers to reconsider traditional approaches to disease control. Researchers at the University of Minnesota have explored potential transmission pathways, including the possibility that vampire bats could spread prions as their range expands northward. While no cases of bat-to-deer transmission have been documented, the scenario highlights the unpredictable nature of the disease. Officials have described chronic wasting disease as a significant threat to deer populations, with implications for hunting and rural economies that rely on wildlife-related revenue.

The challenges of managing the disease have drawn comparisons to other prion diseases, though chronic wasting disease presents unique difficulties due to its spread through wild populations. In Illinois, culls were intended to reduce deer numbers in areas where the disease was detected, but transmission continued. The economic impact of the disease extends beyond ecology, as hunting licenses, gear sales, and tourism contribute substantially to local economies.

The Hunters Left in the Dark

The gap between policy and on-the-ground reality is evident among hunters. In Illinois, those who participated in culls often did so without full awareness of the disease’s complexities. Similarly, in Connecticut, hunters may not realize their deer are being tested for chronic wasting disease when they submit heads for taxidermy. The system depends on passive participation, which may not be sustainable if the disease becomes more widespread.

Labonte encouraged hunters to report deer exhibiting unusual behavior or signs of emaciation. However, early-stage infections are difficult to detect, as symptoms may not appear until the disease has progressed. By the time an animal shows visible signs, it has likely already spread the disease to others.

The ethical questions surrounding culling have grown more pressing as the disease spreads. If eradication is no longer feasible, the purpose of killing deer becomes less clear. Surveillance remains the primary tool, but without a clear path forward, hunters, taxidermists, and wildlife managers face uncertainty. In Illinois, officials have not yet outlined a new strategy, leaving some hunters frustrated while others accept the limitations of current approaches. Skinner emphasized that the decision to end culls was not an abandonment of efforts but a recognition of the need for better tools.

What Happens If It Jumps?

The potential for chronic wasting disease to affect human health remains a concern. The Centers for Disease Control and Prevention has stated that no confirmed cases of transmission to humans have been reported. However, the agency also notes that prion diseases can cross species barriers, as seen with mad cow disease in the 1990s. The incubation period for such diseases can span decades, meaning any human cases might not emerge for years.

Research into potential transmission pathways, including the role of vampire bats, underscores the uncertainties in monitoring the disease. Most states test only a fraction of their deer populations, and while thousands of negative samples may seem reassuring, a single infected deer could contaminate a large area. The disease’s spread has already prompted shifts in wildlife management strategies, with some states moving from eradication efforts to mitigation.

States like Delaware, Pennsylvania, and New York have reported cases, and the geographic range of the disease continues to expand. For now, hunters remain a critical part of the response, reporting sick deer and submitting samples. But as Illinois’ experience demonstrates, even aggressive measures may not be enough. The question is not whether other states will face similar challenges but when—and how prepared they will be.