It is easy to picture a wildlife disease spreading like a stain from its starting point. Missouri's CWD history shows a different pattern: 933 positive deer from 2011 to 2025, each mapped to the section of land where it was killed. For three years, the disease remained within half a mile of a single site in Macon County. Of the counties it now occupies that have mapped locations, most (39 of the 55) had their first detections more than 75 miles from where it began. The farthest was about 240 miles away. There is a cause behind that pattern, and it changes where a hunter should expect the disease to appear next.
KEY FINDINGS
- During 2011 to 2013, Missouri's earliest CWD cluster remained within a half-mile of its starting point in Macon County. It was a classic example of nearby spread: one county and a few survey sections.
- Positive deer have now turned up in 56 counties. Locations are mapped for 55; these data provide no mapped site for the remaining county. Starting in 2014, the first detections in 39 of 55 occurred in separate pockets over 75 miles from the starting point. The most distant was about 240 miles away.
- From 2011 to 2016, the number of newly identified positive locations stayed in the single digits each year. It reached 140 in 2024, showing that the disease is turning up more frequently over time. The count fell in 2019, and the 2025 count covers only part of the year. These totals have not been adjusted for how much sampling was done.
- Movement aided by people is a leading suspected route behind distant, separate clusters of detected cases. That includes hauling carcasses and moving animals through the captive-deer business, although the map cannot establish which route occurred. The county infected next need not be the neighboring county.
IThe half-mile years
2011 to 2013: CWD followed the expected pattern
Macon County, in northern Missouri, was where the state confirmed CWD in free-ranging deer during the early 2010s. The positives from the opening three years of sampling fit precisely what you would expect of a contagious illness carried by an animal on foot: all were within roughly half a mile of one another. Had that pattern held, the current Missouri CWD map would show one expanding patch around Macon. Managing it would mean laying out concentric circles. The pattern broke.
IIThe jumps
Detected cases form separate clusters far apart
In 2014, positives began appearing far beyond the original area. A new focus emerged in Franklin County, 143 miles away, followed by Jefferson at 184 miles. A succession then appeared across southern Missouri: Ste. Genevieve and Perry toward the southeast, plus Taney, Barry, and Christian close to Arkansas in the southwest. Between these clusters lay areas where no cases had been detected. The map cannot establish that those areas lacked disease or that separate introductions created the clusters. Among the 55 positive counties assigned a mapped location, 39 had their earliest detections over 75 miles from Macon.
Swipe table to see every column
| County | First positive | Miles from origin |
|---|---|---|
| Macon (origin) | 2011 | 0 |
| Adair | 2014 | 24 |
| Cole | 2014 | 98 |
| Franklin | 2014 | 143 |
| St. Clair | 2016 | 152 |
| Jefferson | 2016 | 184 |
| Ste. Genevieve | 2017 | 207 |
| Perry | 2017 | 215 |
| Taney | 2018 | 236 |
| Howell | 2021 | 231 |
| Barry | 2021 | 241 |
| Jasper | 2023 | 216 |
IIIWhat jumps mean
Distance gives the signal
Wild deer rarely disperse beyond distances of a few tens, measured in miles. Detected clusters lying 140 to 240 miles away from the starting point, separated by places where cases have not been detected, therefore are unlikely to result from a single deer traveling on foot. A few unusually long dispersals have been documented, though. Wildlife agencies, along with review papers, identify movement of living deer and infected carcasses as routes by which CWD gets into new places. Scavengers and natural dispersal contribute too. Movement by people remains a leading suspected route. These mapped locations cannot confirm that explanation or identify the route taken.
For distant CWD detections, movement by people remains a leading suspected route. The map cannot identify the route that occurred.
IVReading the map
The closest case tells only part of the story
An epidemic that jumps between places makes “my county is clean and so are the counties around it” a false reassurance. Even without detected cases, a county may have possible exposure routes through shared processors handling deer, carcasses carried by hunters, or captive facilities located there or shipping deer there. Our view is that hunters trying to judge CWD's next move in Missouri should weigh these potential routes along with how far away the closest mapped case sits.
NOTES AND SOURCES
- The point for each positive deer marks the center of the Public Land Survey section where that deer was taken. Source: CWD services from the Missouri Department of Conservation (gisblue.mdc.mo.gov). Distances follow great-circle paths measured from the center of the 2011 Macon section.
- The total is 933 deer positive for CWD in 56 counties, with sample years running from 2011 to 2025. Instead of an individual year, 107 records give the span 2022 to 2023. They count toward the overall totals but are left out of the yearly-cadence figure to keep 2022 from appearing too high.
- When and where MDC did its sampling partly shapes the year of initial detection. Finding the first case later does not, on its own, establish that CWD arrived later. Where deer underwent testing may explain some of the separated pattern. Sampling coverage is not tested in this paper.
- “Miles from origin” uses the earliest positive site in each county as the endpoint for measurement.
- This paper covers the geography of spread rather than how common the disease is. Its county totals of positive deer cannot be compared with those of other states, whose sampling practices and disease histories differ.
Fully Drawn Research is an independent data analysis desk, not affiliated with any state wildlife agency, transportation agency, mapping provider or outfitter. Figures trace to Missouri Department of Conservation public CWD data, retrieved June 2026.
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