CWD spreads in Minnesota deer, but COVID-19 may make monitoring harder

White-tailed deer
A white-tailed deer. Chronic wasting disease is spreading north, deeper into Minnesota. The fatal deer disease has been found near the Twin Cities.
Courtesy of Steve Gifford file

Chronic wasting disease has long been established in the wild deer herds of southeastern Minnesota, but this spring, an infected animal was found in the southern Twin Cities metro area. The finding coincides with a suspension of mandatory testing over concerns hunters could spread the coronavirus at testing stations.

The infected deer was staggering, emaciated and drooling. Those are late stage symptoms of the fatal brain wasting disease, which means the animal had been contagious for more than a year.

And even more troubling, no one was sure how the deer found its way to the largely suburban area where it was eventually shot and tested by a Department of Natural Resources conservation officer.

“It was over 100 miles from the other known positives in our state … and from positives in Wisconsin,” said DNR wildlife health program supervisor Michelle Carstensen. “So we’re not really sure where this deer came from.”

Most deer don’t travel that far on their own, so the wildlife managers like Carstensen worry there might have been an established outbreak of CWD in the south metro area for years. 

The DNR wouldn’t have noticed until deer actually showed symptoms, she said, because they’ve been concentrating their testing efforts on southeastern Minnesota.

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The DNR created a new hunting zone in the south metro area, and will allow hunters there to shoot as many does as they can this fall. It’s a common strategy for handling CWD. Bringing down deer numbers theoretically limits contact between deer, and slows transmission of the disease.

It also gives the DNR more brain samples to test for CWD. The University of Minnesota is working on a rapid live test and new mapping techniques, but until it’s finished, killing and testing deer is the only way to track the disease.

This year, that crucial part of CWD management changed. CWD testing isn’t mandatory this year, because some worry COVID-19 could be passed between hunters, at deer testing locations.

Testing is purely voluntary. The last time hunters in CWD infected zones were allowed to skip testing was 2015. Back then, only about a third of hunters bothered getting their deer tested. When it’s mandated, Carstensen says more than 90 percent of hunters comply.

All those tests help the DNR figure out where the disease is, and where it’s going. Losing access to that knowledge would be catastrophic, but Carstensen is hopeful.

“Hunters are used to participating in CWD surveillance,” she said. “So I’m hoping the momentum carries through even though we went to a voluntary system.”

CWD testing locations will be set up with social distancing in mind, she said.