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University researchers find CWD prions at Beltrami County study site; environmental sampling ongoing
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Summary
University of Minnesota researchers reported multiple chronic wasting disease (CWD)–positive carcasses and environmental detections at an 11-acre public-land disposal site in Beltrami County and described ongoing soil and sediment testing to track contamination and persistence.
Mark Schwablander, an associate director at the University of Minnesota Center for Prion Research and Outreach (MINPRO), told the Beltrami County Board of Commissioners that university researchers detected CWD-positive deer remains and environmental prion contamination at a public-land disposal site tied to a quarantined captive herd.
The finding matters because CWD is fatal to cervids and prions can persist in soil and sediment for years, the researchers said. The university team presented results from systematic carcass searches, tissue testing and environmental sampling at the 11-acre site, and outlined next steps for repeated sampling and assay optimization.
The researchers said the site was linked to a quarantined captive deer herd that, in 2021, tested positive after state action. "In April 2021 there was confirmation of chronic wasting disease in an animal in that herd," Schwablander said, and the herd was subsequently depopulated. The herd owner told investigators that carcasses had been taken to the public land for disposal, and that prompted the study and a DNR exclusionary fence erected in 2021.
The university team said field work in 2021 found more than 200 remains (hair, skin, bone and partial carcasses) across roughly 32 locations on the 11-acre site. Researchers extracted 56 samples from 40 different specimens and reported 14 prion-positive samples by a highly sensitive assay called RT-QuIC/RT-QuICK (described as "RT Quick" in the presentation). Based on bone/tooth anatomy and DNA, researchers said the positive remains included at least three adults, one yearling, six fawns and one unknown-aged animal, and some positive specimens matched DNA from the captive herd.
Researchers also described environmental sampling. In 2021 the team collected 124 soil samples around flagged carcass locations and reported 25 positive soil detections; soil was positive at 64% of spots where CWD-positive carcass remains had been found. The team said perimeter soil samples taken at likely runoff points in 2021 were negative, suggesting detections were concentrated inside the fenced area that year.
On water sampling, the researchers said prions tended to partition to fine sediment rather than remaining free in water. Water samples collected in 2022 and early 2025 were negative, but sediment from the site produced detections in lab tests. "We found that the prions partition to the fine sediments in the water," Schwablander said. He added that sediment assay results from samples collected in 2025 were still under analysis at the time of the presentation.
The researchers outlined near-term plans: additional soil sampling (including repeat sampling of sites sampled in 2021 and 2022), continued sediment and water sampling during spring runoff, testing for prions on personal protective equipment to assess decontamination methods, and continued laboratory assay optimization.
Eric Thorsen, the Minnesota Department of Natural Resources area wildlife supervisor, told commissioners members of the public should report deer with unusual symptoms or suspect carcasses through the DNR CWD reporting links. Thorsen said the DNR can follow up, take samples and deliver carcasses to the U of M veterinary diagnostic lab if warranted.
Commissioners asked about human risk and testing turnaround. Schwablander said the prion disease is not caused by bacteria or virus but by a misfolded protein; scientists consider human infection possible in principle but there is no confirmed case linked to CWD. He said tissue testing from deer samples can return results within about 24 hours in the university lab, while environmental samples take longer to process.
The researchers thanked Beltrami County, state agencies and adjacent private landowners for cooperating in access and sampling. They said they would return for additional sampling and continue refining detection methods to monitor prion persistence over time.
Researchers emphasized that much of the sampling and detection work remains ongoing and under analysis. Commissioners did not take formal action during the presentation but were told the work will continue and the university would return with new data.
"We continue to collect and test the sediment and water over time," Schwablander said. "We're going back and testing those at those same sites where I showed you the data from 2021, understanding what happens over the 5 years."
