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Chronic Wasting Disease -- The New Reality

(En anglais seulement)

By: J. Guthrie

Chronic Wasting Disease (CWD) may forever change the way we hunt and manage whitetails — the way humans and whitetails interact. This is the new reality of CWD in North America.

But now it’s time to look beyond the hysteria generated by the popular media and the rumors spread across cyberspace, and look at what is really known about CWD. Our actions now, as deer hunters and managers, will not only shape how this disease spreads across the landscape, but also will shape our future as hunters, managers, and wildlife enthusiasts.
CWD, according to the best available science, is not transmissible to humans. Though CWD-causing prions (abnormal proteins with no DNA), can survive cooking and freezing, there is no evidence you can get Creutzfeldt-Jakob Disease (CJD) — the human version of CWD — by eating venison or handling infected deer. In fact, researchers working with transgenic mice — mice inserted with human genes — have seen some interesting results from experiments. They injected millions of infectious CWD particles into the brains of these “humice” and after 500 days, none developed CWD.

According to CWD researchers, there seems to be a species barrier that prevents the disease from developing in humans. Though CWD and Bovine Spongiform Encephalopathy (BSE or “mad cow disease”) are both caused by prions that attack the brains of infected animals in similar ways, CWD apparently can’t make the jump to humans. BSE appears to be the only member of the family of Transmissible Spongiform Encephalopathy (TSE) diseases that can jump from its host (cattle) to humans. Humans have been living with and eating TSE-infected sheep for hundreds of years without problems. That disease, scrapie, appears to be another TSE disease that can’t make the jump to humans.

It is important to mention that CJD occurs naturally in the U.S. population at a rate of around one in a million. According to the National Prion Disease Pathology Surveillance Center, nearly 600 cases of CJD have been identified in the U.S. since 1997. Of these, only one has been the variant form (vCJD) that is associated with BSE-infected cattle and also expected to the form associated with CWD-infected deer if transmission to humans is possible. However, this person was a British citizen thought to have contracted the disease from eating infected beef while in Europe.

By far, the most common form of CJD in humans is called sporadic CJD, accounting for nearly 90 percent of all CJD cases in the U.S. Less common forms of CJD include familial (genetic link) and iatrogenic (patients receiving infected tissues during surgery).

CWD has been around for at least 30 years in wild elk, mule deer, and whitetails in several western states, notably Colorado and Wyoming. Hunters have been shooting, skinning, and eating animals from this region all this time and none has been diagnosed with vCJD (see sidebar for safety precautions).

Even though the human-health concerns seem to remote at best, it is imperative that we stop this disease from spreading and try and eradicate it in wild and captive populations. Here is where hunters and resource professionals will play a pivotal role.

If you don’t have CWD in your local deer herd, you certainly don’t want it. Though CWD’s appearance in Wisconsin is still somewhat of a mystery, it arrived in nearly every other state by the interstate transportation of infected elk or deer. Minnesota is the latest state to earn a dubious spot on the list of CWD-positive states. It arrived via captive elk and, so far, has not been found in the wild.

Most states have enacted stringent guidelines to prevent potentially infected animals from being transported across state lines. Unless a captive herd has been certified CWD free, it stays put in its home state. While this will help, CWD still could be introduced into new areas by the illegal movement and release of infected animals into either captive or wild herds.
“If you see a trailer of deer or elk on the interstate, or hear about someone illegally releasing some deer to improve their ‘genetics,’ you should immediately inform your local wildlife agency,” said Brian Murphy, QDMA executive director. “Hunters are going to be the key because they are the ones most likely to witness or hear about this sort of activity.”
State wildlife agencies will be counting on hunters in the battle against CWD. “Hunters in all states should help their state wildlife agencies in any way possible,” Murphy said. “We must cooperate in disease monitoring and testing efforts, support their regulatory efforts to prevent CWD introduction, and report any suspect deer or illegal deer movements. Preventing introduction of CWD into new areas and eradicating it from infected herds should be our primary focus. This might require some tough measures, but it’s something we must do in the best interest of the resource.”

One reason for the stringent restrictions enacted by state wildlife agencies, even those in states with no evidence of CWD, is our lack of knowledge. Despite intense scientific investigation of the disease over the past two decades, researchers are still unsure exactly how the disease is spread, though animal-to-animal contact is the most likely route. This is why whitetail populations, especially those in high-density areas, are so vulnerable to CWD.

Now, more than ever, common sense must prevail over hysteria and panic that has gripped deer hunters in CWD-infected areas. For example, Wisconsin is home to more than 1.5 million whitetails and nearly 700,000 deer hunters. These whitetails are not going to manage themselves. Just one season of decreased hunter harvest will have a significant impact on the state’s deer herd, leading to higher deer densities and an exacerbation of the problems already facing the state. Harley Sampson Jr., QDMA’s Midwest regional director, said that friends in the Wisconsin hunting industry are reporting huge drops in pre-season bow, firearm, and equipment sales. Other surveys have found a dramatic decrease in the number of Wisconsin deer hunters taking to the woods this fall. “I would encourage hunters, in states with or without CWD, to get in the woods this fall and hunt,” Murphy said. “Hunting is an important part of identifying and controlling the spread of this disease.”

Jordan Petchenik, a sociologist with Wisconsin’s Department of Natural Resources, recently conducted meetings of focus groups that included hunters, non-hunters, and landowners in the infected area to seek management strategies to control CWD.

“One of the hunters in the group summed it up quite well,” Petchenik said. “He said hunting is no longer just a recreational activity — it’s a job that will safeguard deer hunting for future generations. That’s the crux of the issue. If deer hunting is going to continue, hunters are going to have to play a major part in controlling CWD.” It is also important to note that a huge effort in the science and research community is underway to learn more about CWD and find ways to eradicate it. At the CWD Symposium in Denver, Colorado this August, over 500 researchers, wildlife veterinarians and biologists, state wildlife agency personnel, and epidemiologists met for two days to discuss what they knew about CWD and, more importantly, what they are doing to prevent its spread. Many of these capable and determined soldiers in the CWD fight are the same people who have fought and conquered other wildlife emergencies. Given enough time and support by state agencies and hunters, it is unthinkable that they could not find solutions to this problem.

Numerous studies are already underway, looking at various aspects of the disease. Millions of federal and state dollars have been allocated for research, disease testing, and disease control. Looking beyond the outbreak of CWD in Wisconsin, we have to look back over the last century and remember our past. At the turn of the century, there were fewer than 500,000 whitetails nationwide. After a hundred years of efforts by sportsmen and wildlife professionals, whitetail numbers now exceed 30 million. Whitetails are a resilient and hardy species. Given our best efforts, they will continue to thrive, even in the face of a deadly disease like CWD.

“We are going to win this fight,” Murphy said. “All of us who love this great resource are going to have to make sacrifices. Our satisfaction will lie in the fact that our children and grandchildren will still have the opportunity to enjoy a fall afternoon hunting whitetails.”