New study raises concerns over chronic wasting disease transmission, but not everyone is worried
Whitetail Deer Head Looking Left
A closeup of a whitetail deer looking towards the left
Sandy Thistle spent most of her twenties as a vegetarian. When she decided to start eating meat again in her late 20s, she wanted to kill it herself. This was a natural choice, since she came from a family of hunters.
“It seemed right to me that I should morally and holistically be willing to get my own meat,” Thistle remembers. “Needless to say my dad was thrilled that I joined the family ritual.”
Almost 30 years later, Thistle is still an avid hunter. “I hunt for the meat,” she says. “Which is why I butcher as well. It tastes infinitely better when I do it myself. The meat is clean. I fillet everything off the bone. I make a kick-ass Thai venison/green bean curry.”
This ancient tradition of hunting food has become, for some of Wisconsin’s 600,000 deer hunters, an increasingly worrisome endeavor. The fear is chronic wasting disease, usually shortened to its acronym CWD. It was first discovered in Wisconsin in 2002. Since then, the illness has been found in both wild deer and captive ones on hunting farms, including in Marathon County.
CWD is an infectious disease in cervids — the deer family, including white-tailed deer, elk and caribou — caused by twisted proteins known as prions. It slowly causes brain tissue to become sponge-like, and is eventually fatal. It’s more prevalent in male deer, and because it can take years to manifest, more common in older trophy bucks.
CWD is a transmissible spongiform encephalopathy, an illness group that includes bovine spongiform encephalopathy or “mad cow disease,” Creutzfeldt-Jakob Disease in humans, and scrapie in sheep. All are fatal.
It’s unknown whether eating venison from deer infected with CWD would harm humans. But in May, Canadian researchers released preliminary results of a study showing that macaques can contract CWD from eating meat from CWD-positive deer.
The study results—although neither final (the ongoing research, funded by the University of Calgary, began in 2009) nor yet published in a peer-reviewed journal—have heightened concern because they show that CWD can potentially infect a primate orally.
Canada’s Health Products and Food Branch updated its advisory in response to the findings: “While extensive disease surveillance in Canada and elsewhere has not provided any direct evidence that CWD has infected humans, the potential for CWD to be transmitted to humans cannot be excluded.”
With gun hunting season opening Nov. 18, some Wisconsin venison eaters and processors are changing their approach in response to these findings.
Silver Creek Specialty Meats Inc. in Oshkosh told its customers in late August that it will no longer process wild venison from hunters: “…no matter how small the risk (if any) of humans being infected by the disease we are not, and never will be, willing to put profit before the safety and well-being of our customers.”
Thistle often hunts near Dodgeville, in the middle of an area where CWD has been found. She has routinely tested all of her kills for the illness. So far, all have tested negative.
“I haven’t been in a situation where I’ve had to throw out the meat. But I’m 100% certain I would,” she says. Thistle notes that not all hunters are as cautious as she is.
Some are dismissive of fears about CWD. Retired veterinary pathology researcher Don Davis of Texas has been arguing in nearly identical op-eds published across the country since mid-September that deer hunters have nothing to worry about.
“CWD does not affect people,” he writes. “No evidence shows humans are susceptible to CWD. In other words, we’d be better off worrying about deer-car collisions.”
In an email, Davis says he wrote the op-eds “to try to alleviate any possible concerns that the public might have about the risk of consuming venison that might have been caused by media hysteria not based on scientific facts. More precisely as a result of the unpublished Canadian study on macaques. Sub-human primates are so named because they are not human. Any extrapolation of experimental data from one species to another is often inaccurate, not very helpful, and more often causes unnecessary alarm.”
But local experts counter that caution is prudent in light of the Canadian study. Former Wisconsin Natural Resources Board Chair Dave Clausen, a retired veterinarian from Amery, has studied CWD extensively since it was discovered in Wisconsin.
Clausen explains that the Canadian study does “not mean necessarily that people are going to get it. What it does mean is that hunters should consider the possibility that that could happen and should get their deer tested.”
UW-Madison Wildlife Ecology Professor Michael Samuel’s lab conducts research on CWD in Wisconsin white-tailed deer along with the state Department of Natural Resources and USGS National Wildlife Health Research Center. “[The Canadian study] has certainly made us pay attention to the fact that the risk to humans is probably not zero,” Samuel says.
That non-zero risk is significant because, according to estimates published this year by the Alliance for Public Wildlife (in a paper co-authored by Clausen), in the U.S., “7,000 to 15,000 CWD-infected animals are being consumed by hunter families every year, and this number [is] continuing to rise by as much as 20% per year.”
“As the prevalence rate for CWD increases,” the paper continues, “the number of undetected CWD positive deer carcasses entering the food chain is growing exponentially. By one estimate, in Wisconsin alone, this number was over 4,000 such carcasses for 2015.”
For now, there have been no known cases of human prion disease linked to consumption of CWD-positive deer.
“We won’t know for sure unless someone comes down with it,” Clausen says. “But the problem is that once someone comes down with it, that horse is out of the barn.”
The easiest way for hunters to be sure their deer are safe to eat is to have them tested. DNR offers free testing at over 100 sampling stations.
“Ideally, the samples should be taken as soon as possible after harvest,” the department’s website says. “The samples needed for CWD testing are located near the base of the deer’s skull and first several inches of neck.”
If unable to test within five days, the head and a portion of the neck should be frozen, the site says.
Thistle appreciates the service but wonders how long the state will continue to offer it. “One of my anxieties has been what to do if the state no longer offers testing.”
Hunters can also pay for their own testing, which costs $33 if taken directly to the Wisconsin Veterinary Diagnostic Laboratory, or around $100 by a certified lab.
The U.S. Centers for Disease Control and the World Health Organization both recommend against eating an animal that tests positive for any transmissible spongiform encephalopathy.
The DNR did not provide statistics of how many deer killed in the state are tested for CWD. Department spokesperson Erin Larson says in an email, “Since we do not offer sampling locations everywhere in the state and target specific areas certain years, a statewide percentage of harvested deer sampled for CWD would not mean anything.”
The department has done surveys of hunters who tested their deer. In the 2016-17 season, 27% of hunters who killed a deer that tested positive for CWD decided to eat the venison. The year before it was 28%.
But the DNR’s Eric Lobner adds, “We are aware of hunters that initially indicate they will be consuming the meat that later turn around and dispose of the meat. I suspect the opposite happens as well… As a result, I think it is safe to say that we don’t really know how many hunters actually eat the venison from deer that test positive for CWD.”
The state Department of Health Services keeps a registry of people known to have eaten infected venison. The registry has not yet been updated to include the 2016 season, but 1,454 names are on it for 2003–2015, according to the department’s Elizabeth Goodsitt.
Former DNR Wildlife Bureau Director Tom Hauge, who hunts deer with his family, wants to see an aggressive campaign encouraging all hunters to test.
“From a practical perspective—a deer hunter’s perspective—we really need to make it as convenient as possible to participate in testing the animals and be able to get test results in a very quick fashion,” he says. “And then it’s still up to the hunter to make a decision, if it tests positive, to consume it or not.”
Many argue the state needs to be more proactive in fighting the disease. Clausen’s paper recommends regulators ban the movement of any potentially infected cervids, alive or dead, and any other potentially infectious materials including equipment and trailers; mandate free, rapid testing of all cervids harvested in CWD-affected areas; ensure proper disposal of CWD-infected material so it doesn’t reach food or feed chains; and invest in “accountable research and science-based policy.”
If Wisconsin enacted these strategies, Clausen and others believe it would slow the spread of CWD.
In 2010, the Natural Resources Board approved the state’s 15-year plan to fight CWD. In 2016, the DNR initiated the first five-year review of the plan and formed a stakeholder advisory group to perform the review.
The “Report on the first review of the Wisconsin CWD Response Plan” was released in early 2017. Among its many recommendations was a statewide baiting and feeding ban. Instead, the Legislature rolled back the baiting and feeding ban in a number of counties; Gov. Scott Walker signed the bill into law in August.
Since about 2006, the DNR has downgraded its efforts from active CWD management strategies that included sharpshooters killing deer that look ill, and longer hunting seasons encouraging CWD testing. Now the state just does testing and monitoring, in part because such initial efforts were unpopular.
Bryan Richards, USGS National Wildlife Health Center Emerging Disease Coordinator, calls efforts to prevent CWD from becoming well established “a balancing act that Wisconsin did not excel at.”
In 2011, Wisconsin hired the so-called “Deer Czar,” James Kroll from Texas. Richards characterizes Kroll’s recommendations as “passive.”
“And passive,” Richards adds, “equates to really no active management whatsoever.”
Hauge reflected on Wisconsin’s response to CWD when he retired from the DNR last year. “I wish I could have put that genie back into the bottle,” he told columnist Patrick Durkin. “I don’t regret our early actions to try to control CWD, but we probably lost the communications battle with those who want to dismiss its risks.”
“I’m very, very aware that low risk is not no risk,” Hauge added. “Each time you pass a CWD-positive animal through a human body, it’s Russian roulette.”
DNR Wildlife Health Section Chief Tami Ryan says the state allowed for bigger harvests in areas where CWD was prevalent in an attempt to reduce the population and spread of the disease. “Now we’re seeing population growth, and with that, an increasing trend in both distribution and prevalence of disease,” Ryan says. “Illinois is still responding to disease in their state by localized culling, whereas we haven’t been doing that for quite some time.”
Hauge, in an interview, says the state should work with landowners and hunters to provide incentives to remove animals that appear diseased. If more sick animals are removed than infected each year, CWD trends could be reversed.
Hauge also sees pressure growing for the state to take action. “The increasing prevalence, and then this most recent information with regards to the macaque study adds to that momentum.”
The deer are too important to Wisconsin, he adds. “The white-tailed deer is not only the state wildlife animal, but it’s just fundamentally woven into the culture of our state.”
Another area of concern are deer farms. The Department of Agriculture, Trade and Consumer Protection announced Oct. 20 that CWD-positive white-tailed deer were found at a Waupaca County hunting ranch. CWD has now been detected in captive deer facilities in Eau Claire, Marathon, Marinette, Oconto, Shawano and Waupaca Counties—all areas where CWD has not yet been found in wild herds.
Once CWD is found in a facility, the agriculture department allows the facility to continue holding hunts, transfer deer among properties under the same ownership, and transfer dead deer off the properties. The state does not require any change in fencing to decrease the potential for escape or contact with wild deer.
Some experts say these policies risk infecting more wild deer. Richards with the USGS stresses that CWD-positive captive facilities “without a doubt constitute a risk to free-ranging deer on the other side of the fence.”
Wisconsin State Veterinarian Paul McGraw counters that the department of agriculture “has a very strong quarantine in place.” He adds that there’s “not a lot of nose to nose contact, very little ever, between farms and wild deer…. Pointing a finger at wild versus farmed deer is not helpful.”
McGraw cites a 2007 USDA study completed in Michigan finding only two direct, naso-oral contacts between wild and farmed deer during more than 77,000 hours of camera monitoring.
But USDA’s CWD standards state, “In areas where CWD is not known to be present in free-ranging wild cervids, a second barrier is recommended that is adequate to prevent fenceline contact of wild cervids with a CWD-exposed herd.”
Nose to nose contact is not the only way deer could be exposed. Studies have shown that CWD prions can persist in soil and water and bioaccumulate in plants, especially grasses.
Wisconsin’s five-year CWD stakeholder review recommends “enhanced fencing (e.g. double or electric fencing) for facilities with CWD positive cervids… to minimize the risk of disease transmission.”
But a bill to do that, introduced in June, hasn’t received a hearing.
Hauge is dumbfounded by the lack of a response from DNR and the department of agriculture. “I’m surprised that we’re still waiting and have not seen anything from the two agencies regarding what their plans are for implementing those yet,” he says. “I would have thought they would have tried to put something out in advance of this fall’s deer hunting seasons.”
Jay Settersen’s been hunting about 35 years, since he was 13. Raised by a single mom, he learned the sport in part from his friend, Rob Gottschalk, and Rob’s dad. Jay and Rob got hooked on bow hunting early on.
For Settersen’s family, hunting is a way of life that “reaches way beyond the actual hunt.” Many of his best friends are hunters and “hunting is a big part of our friendship and what keeps us in communication, staying in touch, and rooting for each other,” he says. “There’s so much camaraderie that goes with that. It’s amazing how hunting is factored into so many parts of my life.”
His children are friends with his friends’ children and the families hunt and eat meals together. During the winter, they make venison jerky in a smoker while watching football on TV. “The kids understand where the food comes from and why working on the land to improve the land is important so the herd is healthier,” he says. “Deer hunting is the driving force behind all of it.”
Nourishment is central to the act of killing. “If I’m not going to eat it, I’m not going to kill it,” he says. “There has to be a reason for me to kill an animal.”
He hunts nowadays in three areas: in Jackson County near Black River Falls south of Eau Claire, in Richland, and from their deer camp in Marinette County. Of those areas, Richland County is near core CWD and Jackson County until recently had a baiting-feeding ban because CWD had been found nearby.
In October, Settersen’s son killed his first buck with a bow and arrow. When he dropped off the deer to be tested and butchered, Settersen ended up chatting with some local hunters. They were surprised he had tested the kill for CWD.
“I don’t know if it’s because… they’re concerned they might have more rules to abide by if it’s present and they don’t want anyone telling them what to do,” Settersen speculates. “So I took the chance to say to them, ‘Well, if I’m not feeling well, I’d want to go to the doctor sooner rather than later, before it’s a really big problem.’”
Settersen doesn’t know what can be done about the disease, but thinks it’s important for hunters to have as much information as possible. “Eventually everyone in the state will have a better understanding of what it is and how it moves, and then with that information, they can get buy-in,” he says. “Without that, everyone throws ideas out there, says what they think, and it’s hard to get folks to assemble and work in a positive direction.”