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Deer Lure Bans are Band-Aids for CWD

By Patrick DurkinAugust 18, 201512 Comments
Problems posed by chronic wasting disease will likely soon go beyond hunting issues like whether to ban the use of commercial deer urines.

Problems posed by chronic wasting disease will likely soon go beyond hunting issues like whether to ban the use of commercial deer urines.

Are bowhunters really supposed to believe the woods and forests of Vermont, Virginia, Alaska and Arizona are now safer from chronic wasting disease because these states banned hunters from using elk- and deer-urine scents?

Given what researchers are learning about crop-plants taking up and holding CWD-causing prions and likely passing them to browsing critters and livestock, we have far larger year-round problems than random hunters spritzing mock scrapes in autumn with bottled urine from known, regulated deer farms. And given that these nearly indestructible prions can be spread in dirt and dust particles, how long before researchers find them in plant pollens carried on a breeze?

Besides, even as prion tests keep improving, no one knows for certain how deer become infected with CWD. Is it through deer-to-deer contact, by consuming bodily wastes dropped or dribbled onto edible plants, or by eating grains or leaves from plants whose roots take up prions from contaminated soil? In contrast, when’s the last time deer congregated day after day, month after month around a mock scrape as if it were a bait pile?

We don’t even know if we should be more concerned about CWD’s impacts on deer populations, or its potential to infect humans who eat prion-contaminated meats, plants or grains. Worse, the still-thin science on CWD seems destined to stay that way, given how state and federal lawmakers, policymakers and agencies keep ignoring its mounting problems.

Take Wisconsin, for example, home to the nation’s worst CWD outbreak. If you want guidance on whether to eat venison from wild deer, you won’t find it on the Department of Natural Resources’ CWD website. The closest you get is a “Processing your deer” page with precautions on gutting, field dressing and cutting up deer, and cleaning up afterward.

Nowhere, however, does the DNR explain why you must be so cautious. The lead paragraph simply says there’s no strong evidence CWD can infect humans, but that the World Health Organization and the Centers for Disease Control and Prevention recommend not eating venison from CWD-positive deer or elk. To get specifics from the WHO and CDC, you must visit their websites.

If you want to read Wisconsin’s actual consumption advice, you must click a link to see this specific bold-faced message: “The Wisconsin Division of Public Health recommends that venison from deer harvested inside the (35-county CWD-Affected Area) not be consumed or distributed to others until CWD test results on the deer are known to be negative.”

If a deer carrying CWD urinates, defecates or drools on crops, the plants aren’t easily washed clean of the contaminants.

If a deer carrying CWD urinates, defecates or drools on crops, the plants aren’t easily washed clean of the contaminants.

You’d think that important caution would be prominently printed on the DNR’s CWD pages. But no, you must hunt for it, much as you must hunt for a place to get your deer tested for CWD. If Wisconsin’s Department of Health Services recommends not eating venison until it tests negative for CWD, why isn’t testing more convenient, and why are fewer deer than ever being tested?

David Clausen, a retired veterinarian who served 7½ years on Wisconsin’s seven-citizen DNR Board, including four years as its chair, notes that the DNR tests only one-fifth as many deer as it did in the early 2000s. In fact, in 2014 it tested 80 percent fewer deer than in 2002 and yet found 60 percent more CWD cases.

Clausen said he’s alarmed by the increase in “positive deer carcasses” likely entering people’s kitchens from Wisconsin’s worst CWD region, which includes Dane, Iowa, Sauk, Rock, Green, Columbia, Lafayette, Richland and Walworth counties. To estimate the problem, Clausen multiplied the deer kill in those nine counties between 2002 and 2013 by the percentage of CWD-positive tests for each county. His graph shows a steady rise from 221 potential CWD-positives in 2002 to 2,430 potential positives in 2013.

“A statistician might argue with my numbers, but what can’t be argued is the trend,” Clausen said. “And given that the DNR samples so few deer these days, I don’t think they have a handle on the disease’s distribution anymore.”

Clausen concedes there is no evidence humans have contracted CWD from eating infected venison, and that the odds of it transmitting to humans probably remain small. However, “The odds have never been zero.” Clausen notes that a 2005 study that reported a “substantial” species barrier from elk and deer to humans was recently revised after new findings prompted its authors to re-examine tissues from the original study.

Although it seems unlikely that CWD can cross the species barrier from deer to people, the chances of it happening have never been zero.

Although it seems unlikely that CWD can cross the species barrier from deer to people, the chances of it happening have never been zero.

“Upon further review, their study and another recent study (which found two in 20 ‘humanized’ transgenic mice with clinical prion infections) pretty much blow the original study out of the water,” Clausen said. “That doesn’t mean human infection is a foregone conclusion, but it emphasizes that the science of CWD continues to evolve, and points out the need for more research and surveillance. It also sends a precautionary message to those eating untested venison or venison testing positive.”

Clausen said other research makes him wonder if venison consumption should be our primary concern. Prions can get into our systems through plants, too. Researchers at the University of Texas Houston and Colorado State University found that wheat grass surfaces contaminated by urine, brain and feces were not easily washed clean. Further, Chris Johnson at the National Wildlife Heath Center in Madison found that alfalfa, barley, corn and tomatoes could take up prions from the soil. And hamsters fed prion-contaminated plant samples in the UTH and CSU study developed prion disease.

Clausen thinks the possibilities of plant-based CWD infections could eventually threaten agriculture across the United States, not just Wisconsin.

“How anxious do you think the Brits would be to feed their cattle grain imported from areas where CWD-infected deer are urinating and defecating on plants that grew those grains?” Clausen asks. “Closer to home, who’d want a load of hay from those fields? If markets are threatened, agriculture will respond. A threat to agriculture is a threat to wildlife.”

Patrick Durkin
President at Wisconsin Outdoor Communicators Association
Patrick Durkin is a lifelong bowhunter and full-time freelance outdoor writer/editor who lives in Waupaca, Wisconsin. He has covered hunting, fishing and outdoor issues since 1983. His work appears regularly in national hunting publications, and his weekly outdoors column has appeared regularly in over 20 Wisconsin newspapers since 1984.
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