Two States, Opposite Bets: How Wisconsin and Missouri Manage CWD

ISame disease, two doctrines

Contrasting CWD management philosophies

Wisconsin and Missouri have chosen opposing paths for managing chronic wasting disease, reaching different answers to a shared question. CWD has been detected over a broad area in each state. Throughout Wisconsin's testing program, positives have appeared in 52 of 73 counties. Missouri reports that most of its counties either have recorded a case or sit within a 10 miles radius of one. Each state must weigh aggressive management against what hunters will tolerate. During their 2026 seasons, Wisconsin is tightening its approach as Missouri relaxes its own. Disease stages and settings differ between these states, making this a policy comparison rather than a controlled experiment.

IIWisconsin: manage the density

Banking on intervention

Wisconsin bases its strategy on the idea that fewer deer per acre means slower transmission. The Southern Farmland zone is the epicenter, accounting for roughly 87% of Wisconsin's positive results. No other zone in Wisconsin has a more liberal antlerless allocation. Many counties there allow antlerless harvest without a practical limit. Sampling is required where affected, and testing is free at over 240 sites. This approach is costly and intrusive, demanding considerable effort from hunters. Survival figures help explain the choice: infected does have about half the annual survival rate of healthy does (41% versus 83%). With prevalence beyond the model's threshold for herd decline, Wisconsin is placing its main bet on reducing density.

IIIMissouri: simplify the rules

Banking on fewer regulations

Missouri is taking the opposite approach. For 2026 to 27, the Department of Conservation is eliminating the formal CWD Management Zone designation altogether. The zone had expanded to 83 counties by 2025 to 26. Counties with detected CWD will instead be listed in the regulation booklet. Missouri is also lifting antler-point restrictions across the state and ending the firearms season’s separate CWD portion. MDC says the zone designation is no longer necessary because most Missouri counties have recorded a CWD case or are within 10 miles of one. It also says removing the designation makes regulations easier for hunters to follow. Mandatory sampling shifts to a four-year cycle covering every county. Targeted measures remain, including feed and mineral bans within ten miles of any positive case and deer removal after the season in hot spots. The extensive zone-based framework is being taken away.

Wisconsin is calling on hunters to help lower deer density. Missouri is simplifying regulations while rotating mandatory sampling through every county. Each approach offers a defensible way to limit herd declines linked to CWD. Different stages of the disease may call for different policies.

IVWhy it is a real experiment

What deserves a closer look

Disease conditions differ across these herds. Southwestern Wisconsin is much further into CWD than most Missouri areas, and those conditions shape each state's choices. If Missouri's approach, with fewer rules and surveillance as its priority, keeps prevalence steady while reducing hassles for hunters, other states will adopt it as a model. If prevalence in southern Wisconsin drops under its density-reduction approach, that result by itself would neither demonstrate a policy effect nor reveal the outcome deregulation would have produced. Adult-female prevalence is a useful measure to follow: it means the proportion of adult female deer infected with CWD. The estimated threshold for herd decline comes from modeling in a particular study. It is no universal dividing line that determines whether a policy works.