Chronic Wasting Disease – Wildlife management

Overview

Chronic Wasting Disease (CWD) is considered a recent occurrence in wild cervids in Canada and there is no evidence that it is a natural long-term component of our native ecosystems. As such, the effects of the disease in wild populations are still being documented.

Impact on deer populations

Within affected jurisdictions the disease generally is not widespread and often occurs in local adjacent deer populations.

Mortality does not seem to affect overall productivity in infected populations in the short term, although models and data collected in Colorado, and more recently in Wisconsin, suggest that deer populations at the heart of an affected area decline and disappear over the long term.

• Infected populations in the core areas of the western US, where CWD has been present for a few decades, have a lower proportion of older-aged deer, and particularly fewer older adult males.
• Infected deer populations have a lower mean age than uninfected populations.
• Infected females die prematurely and do not provide their full potential to the ongoing productivity of the population, that is, the fawns that would have been produced in later years are not available if the doe dies prematurely of CWD.
• CWD slowly expands across the landscape to adjacent populations. Natural or genetic barriers to limit the spread of CWD have not been found.
• There is no known treatment or vaccine to control CWD infections.
• All deer and elk infected with CWD die prematurely.

Prevalence of CWD (percentage of deer infected) continues to increase in populations with long-standing infection. As the prevalence increases, the effects in local populations are more pronounced.

In the eastern USA, the finding of CWD in wild and farmed white-tailed deer, particularly in Wisconsin and Illinois, causes significant concern for wildlife managers. Many states and provinces have developed plans for preventing or managing CWD.

Recommendations to guide wildlife management agency programs were provided at a CWD Workshop in Edmonton in 2008. See the 'Chronic Wasting Disease Workshop: Wildlife Agency Responses Across North America – Final Report' at Chronic Wasting Disease – Reports

Additional information is provided on our Chronic Wasting Disease – Reports page.

Restrictions for cervid, transport

Many jurisdictions have developed new restrictions on the intra- and inter-jurisdictional movement of farmed cervids and wild cervid parts in an attempt to limit potential spread of CWD.

A list of state and provincial regulations or policies is available at Chronic Wasting Disease and Cervidae Regulations in North America

Alberta introduced voluntary transportation guidelines in 2009. See the document, 'CWD Guidelines: Deer Carcass Transportation and Handling', at CWD – Information for Hunters.

Salvaging roadkill for use as bait

Using roadkill wildlife for bait in permitted situations is a valid way to gain added value from these animals. But there are some restrictions, as outlined in Chronic Wasting Disease and Roadkill Salvage in Alberta.

CWD and BSE

A related concern about CWD is the potential for misrepresenting it as being equivalent to bovine spongiform encephalopathy (BSE), the infamous "mad cow disease," a prion disease of bovids (cattle).

BSE has been associated with a similar prion infection in humans, variant Creutzfeldt-Jakob disease, and poses worldwide concern for public health and agricultural economics. However, CWD and BSE are not the same. For details about CWD and human health, see CWD – Public health.

Based on the documented risk to wild deer populations, and the perceived human health concerns, wildlife managers throughout Canada and the US expend considerable time, effort, and monies on surveillance programs aimed at defining exactly where CWD occurs or does not occur in the wild.

A map of current distributions of CWD in North America is maintained by the CWD Alliance at CWD: Map.

CWD surveillance programs

Alberta began surveillance of wild deer and elk for CWD in 1996. Submission of heads of hunter-killed deer is the primary source of surveillance samples, supplemented with testing of clinical suspects (deer that display behaviour or body condition consistent with possible CWD infection).

• Particular emphasis is placed in testing heads of deer killed in the areas at risk for CWD in east and central Alberta, although the program accepts heads from deer or elk killed anywhere in Alberta.
• Over 90,000 heads of wild deer and elk have been tested since the program began.
• There are numerous research projects underway to better define:
  • host range
  • method of transmission
  • diagnostic tests
  • impact on wild cervids
  • risk to the public and livestock

Much of the research effort in Alberta is funded through the Alberta Prion Research Institute, a component of Alberta Innovates Bio Solutions. Visit Alberta Prion Research Institute.

For general information and summary surveillance results from farmed and wild cervids in Alberta, see CWD Surveillance and response.

For the latest information regarding CWD-infected wild deer in Alberta, see CWD Updates.