Chronic Wasting Disease
About CWD and Transmission
Chronic Wasting Disease (CWD) is caused by a misfolded protein called a prion. All mammals produce normal prions that are used by cells, then degraded and eliminated, or recycled, within the body. When disease-associated prions contact normal prions, they cause them to refold into their own abnormal shape. Scientists believe that prions likely spread between animals through body fluids like feces, saliva, blood, or urine, either through direct contact or indirectly through environmental contamination of soil, food, or water. It is unknown how many years prions can survive in the environment but is suggested this could be into the double digits.Citations Top of Page
Although some unpublished research has suggested that CWD could be transferrable from cervids to humans, results of these laboratory experiments have never been reproduced. In short, there is no strong scientific evidence indicating that there is a risk of CWD occurrence in humans.Citations Top of Page
There is no known strategy for effectively eliminating or slowing down the spread of CWD. All attempts to slow down the spread and prevalence of CWD are experimental in nature and therefore should be approached in a systematic, hypothesis-based scientific approach to applied management. Results from the experiments should be used to evaluate the hypothesis and adapt strategies if necessary. Using this approach would produce insights valuable to Alberta in the long-term, and potentially helpful to other jurisdictions that have CWD on the landscape.Citations Top of Page
CWD Resistance and Vaccines
Most existing CWD research focuses on the causes and nature of the disease. New research is now also looking at the possible existence of CWD-resistant animals. A greater understanding of this aspect of the science will be essential for assessing current strategies and future options. There is currently no vaccine, but scientists are still exploring the options.Citations Top of Page
In the last 20 years, our collective knowledge on CWD has grown, but uncertainty on the most effective management approaches remains. Alberta has opted to dramatically increase mule deer harvest rates across many wildlife management units in the southern and eastern parts of the province. All the mule deer in an area could be eliminated, but that will not eradicate CWD, since it can survive for many years in the environment and exists in other species such as moose, elk, and especially whitetail deer. Uniform and oversimplified increases in harvest are not a proven strategy, and Alberta has no mechanism for assessing outcomes from the approach currently being undertaken.
If no regulations exist to prevent carcass movement or offer safe locations to dispose of carcasses, increases in harvest could actually increase the spread of CWD as hunters congregate to certain areas and bring harvested animals home to various areas of the province.
If efforts are undertaken in Alberta to understand the possible the efficacy of management options, APOS is encouraging a systematic and science-driven approach that has measurable outcomes, so that strategies can be adjusted adaptively as needed. Such an approach could provide practical insights into management that will be relevant well beyond the borders of our province.