by CHRIS ROGERS
A deer killed near Pickwick last month was likely infected with chronic wasting disease (CWD), a Mad Cow-like brain disease that affects deer and elk, according to the Minnesota Department of Natural Resources (DNR). The deer was shot just two and a half miles from an infected — and now quarantined — deer farm in Cedar Valley. If initial results are confirmed, the Pickwick buck would be the first CWD-positive wild deer found in Winona County.
CWD is always fatal and no treatment exists. Infected animals can live and spread the disease for years before they show symptoms: drastic weight loss, stumbling, drooling, confusion, and loss of fear of humans. The disease is common in southern Wisconsin and spreading. Since the first detection in 2002, several captive deer and elk farms across Minnesota have tested positive for CWD, including a Cedar Valley deer farm where CWD was discovered in late 2017. An outbreak of the disease in wild deer near Preston, Minn., has been growing. Until recently, wild deer in Winona County appeared to be free of the disease, but the suspected CWD-positive buck found outside Pickwick follows the discovery earlier this winter of a CWD-positive deer just south of the Winona-Houston county line. Both are bad news for Winona County’s deer population and efforts to contain the disease.
The Pickwick buck was shot two weeks ago during the first weekend of a recent special hunt, when the Minnesota Department of Natural Resources (DNR) allowed hunting outside the normal season in order to sample more deer for CWD and gain a better understanding of the status of the disease’s spread. Over the last two weekends, DNR staff were stationed at numerous spots across Southeast Minnesota to collect lymph nodes from harvested deer brought in by local hunters. The lymph nodes were then shipped off for testing to check for CWD.
An initial screening test found that the Pickwick buck was likely infected with CWD, but DNR officials will not know for sure until later this week, when the results of a second test are returned. The initial screening tests are designed to quickly filter through hundreds of samples and identify possible infections. They are not always right. Out of thousands of deer sampled in recent years, DNR officials said they have gotten a few false positives — suspected infections that were later shown to be CWD-free by a second test — but that is not how it usually goes. “I’m not holding my breath,” DNR Wildlife Research Manager Lou Cornicelli said of the second test on the Pickwick buck. “I have no reason to think it won’t come back as confirmed,” he added.
When CWD infections were found at the Cedar Valley deer farm — along with sagging fences that could have allowed wild deer to enter the farm’s deer pen — DNR officials were concerned that the disease would spread from the captive deer to wild deer. Until recently, it appeared that Winona County had dodged that bullet, but the discovery of the Pickwick buck just two and a half miles from the infected farm and the earlier discovery of a CWD-positive deer near Money Creek — eight miles from the farm — raise the possibility that the infection could have spread from the farm. However, the CWD-positive wild deer could have also wandered from the existing infection zone near Preston or been infected by other sources — perhaps a contaminated carcass brought to Winona County from Wisconsin.
“It’s hard to say. You can’t prove that it did and you can’t prove that it didn’t,” Cornicelli said when asked whether the new infections came from the Cedar Valley farm. “Unfortunately, this will be the unanswered question that will be debated on social media long after I retire,” he added.
Both the CWD-positive deer found near Money Creek and the suspected CWD-positive deer found near Pickwick were bucks, and bucks tend to travel around more than does do. If the DNR finds a CWD-positive doe near Cedar Valley, that would lend credence to the idea that there is an established infection in Winona County and the infected deer are not simply wandering in from Preston, DNR Wildlife Health Program Supervisor Michelle Carstensen said.
Even if there is not an established infection in Winona County already, the presence of infected deer could start one. Scientists believe that CWD is caused by misshapen proteins called prions. The urine, saliva, blood, and feces of infected animals contain prions, and those prions can remain infectious for years. So CWD can spread both through animal-to-animal contact and through contact with soil, food, water, or surfaces that have been contaminated by prions. That means that even if the Pickwick buck wandered to Winona County from Preston, it could have been spreading CWD prions as it went. “That’s one of our concerns — that they shed these prions for a fairly long period of time before they actually die from the disease or die from some other cause,” Cornicelli acknowledged. “We’re certainly worried about environmental contamination, but we’re more worried about animal-to-animal contact,” he said. That is why the DNR has banned feeding deer in Southeast Minnesota — to avoid attracting groups of deer together, he added.
The DNR is still awaiting initial test results from deer sampled last weekend. State officials expect those results to come back next week.
Citizens can help the DNR prevent the spread of CWD by following bans against feeding deer and moving deer carcasses out of areas affected by CWD. Citizens may also report sick deer or dead deer to the DNR by calling the DNR Rochester office at 507-206-2862. More information is available at www.dnr.state.mn.us/cwd/index.html.
Correction: The previous headline for this story incorrectly stated that the suspected CWD-positive deer was found in Cedar Valley. The deer was found in the neighboring valley, outside Pickwick.