Chronic Wasting Disease (CWD)

Summary

Chronic Wasting Disease (CWD) is a progressive, fatal, degenerative neurological disease occurring in farmed and free-ranging deer, elk, and moose. CWD can reduce the growth and size of wild deer and elk populations in areas where the prevalence is high, and is of increasing concern for wildlife managers across North America. As such, the number one objective in the management of CWD is to prevent its spread into new areas. Generally, increased attention to, and funding for, regular screening and testing of cervids within a state is necessary to ensure that a timely response to a CWD outbreak is possible.

Introduction

Chronic Wasting Disease (CWD) is a progressive, fatal, degenerative neurological disease occurring in farmed and free-ranging deer, elk, and moose.  The disease was first recognized in 1967 as a clinical 'wasting' syndrome of unknown cause in captive mule deer in Colorado.  CWD belongs to the family of diseases known as transmissible spongiform encephalopathies (TSEs).  TSEs include a number of different diseases affecting animals or humans including bovine spongiform encephalopathy (commonly known as “Mad Cow Disease”) in cattle, scrapie in sheep and goats, and Creutzfeldt-Jacob disease in humans.  Although CWD shares certain features with other TSEs, it is a distinct disease affecting only deer, elk, and moose.  There is no known treatment or vaccine for CWD. 

CWD is a slow and progressive disease.  Because the disease has a long incubation period, deer, elk, and moose infected with CWD may not present any visible signs of the disease for a number of years after they become infected.  As the disease progresses, deer, elk, and moose with CWD show changes in behavior and appearance.  These clinical signs may include progressive weight loss, stumbling, tremors, lack of coordination, blank facial expressions, excessive salivation and drooling, loss of appetite, excessive thirst and urination, listlessness, abnormal head posture, and drooping ears.

Issue

The agent that causes CWD and other TSEs has not been completely characterized.  However, the theory supported by most scientists is that TSE diseases are caused by proteins called prions.  The exact mechanism of transmission is unclear , although evidence suggests CWD is transmitted directly from one animal to another through bodily fluids and tissues.  CWD is of increasing concern for wildlife managers across North America. 

As such, the number one objective in the management of CWD is to prevent its spread into new areas. In an attempt to prevent or slow the spread of CWD to new areas, many states have passed regulations banning the transportation of carcasses taken in CWD-positive states, begun to implement the United States Department of Agriculture’s CWD Herd Certification Programs for farmed cervid facilities, and/or have banned deer baiting (which congregates animals and allows for possible transmission through saliva).  Several states have also recently adopted regulations banning the use of urine-based attractants for whitetail deer,   though the science surrounding the possibility of transmission through urine remains questionable at best.  

Points of Interest​

  • In areas where CWD occurs, only a relatively small number of animals are infected. Even in the parts of Wyoming and Colorado where chronic wasting disease has existed for at least 30 years, an average of less than 6 percent of deer are infected.
  • Although no cases of CWD have been found in humans yet, a recent study conducted in Canada indicated that the spread of CWD in humans might be possible. The study found that macaque monkeys, primates and thus human’s closest relatives, contracted CWD from eating contaminated deer meat.
  • CWD has currently been detected in wild cervid populations in 25 states: Arkansas, Colorado, Illinois, Iowa, Kansas, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Mexico, New York, North Dakota, Ohio, Oklahoma, Pennsylvania, South Dakota, Texas, Utah, Virginia, West Virginia, Wisconsin, and Wyoming.  CWD has been found in farmed cervid populations in 15 states: Colorado, Illinois, Kansas, Maryland, Minnesota, North Dakota, Nebraska, New York, New Mexico, South Dakota, Utah, Virginia, Wisconsin, West Virginia, and Wyoming.
  • Only boned out meat, antlers, hides, and ivories should be transported from CWD contaminated areas to prevent environmental contamination through movement of carcasses.
  • A recently tested vaccine in Wyoming resulted in a potential negative effect associated with the vaccine, in that inoculated elk were found to be about seven times more likely to develop CWD than untreated animals.
  • In 2015, Vermont and Virginia both banned the use of urine-based attractants through their regulatory process.
  • In recent years, Pennsylvania has also considered banning urine-based attractants out of fear of the spread of CWD. 
  • Research in 2015 indicated that grass plants can bind, uptake and transport infectious prions, complicating containment strategies in agricultural areas.
  • In 2016, New York contemplated a change in regulations involving banning urine based attractants. 
  • In 2017, Montana enacted SB 173, calling for a ban on any urine that is not from confirmed CWD-free herds (Archery Trade Association approved).
  • The West Virginia Division of Natural Resources strongly recommends that hunters do not use urine based attractants out of fear of spreading CWD. 

Moving Forward

Responses to the potential spread of CWD vary by state depending on the perceived level of risk and the concerns of stakeholders. State legislators are encouraged to educate themselves on the status of CWD in their state and to work with their fish and wildlife agency to determine what protections are needed in their state to prevent the spread of CWD within their boundaries. Generally, increased attention to and funding for regular screening and testing of cervids within a state is necessary to ensure that a timely response to a CWD outbreak is possible. 

Contact

For more information on this issue please, please contact Brent Miller at bmiller@congressionalsportsmen.org.

Share this page

Your opinion counts

Chronic Wasting Disease (CWD) has been making the headlines recently, with several new states and a Canadian province testing positive for the disease, and many states implementing new rules to prevent its spread. How has this increased public awareness of CWD affected you?

Vote Here
Get Involved

We work hard to educate elected officials about issues important to you, but we can't do it alone. Find out how you can get involved and support CSF.

Read More