Photo by Michael R. Jeffords

August 1, 2018

Chronic Wasting Disease Introduction, Management and Adaptable Processes of Dynamic Disease

Chronic Wasting Disease (CWD) is a disease caused by an infectious form of a protein called a “prion.” CWD affects animals in the cervid family, which includes deer, reindeer, elk and moose. The visible signs and symptoms of CWD develop slowly, gradually getting worse over a period of several months to a year. These signs include thirst, difficulty in swallowing, weight loss and severe neurological damage. Over time, CWD affects how infected animals move and respond to their surroundings. There are no vaccines available for CWD and it is not treatable, even when detected in a timely manner. There is no record of a deer surviving CWD after contracting it.

Three white-tailed deer with trees in the background.
Photo by Michael R. Jeffords

Negative impacts of CWD on population growth and on the overall health of the deer herd are well documented. The disease has been identified in both captive and free ranging cervids, and there are concerns that CWD could spread to other species of animals. Managing the disease is challenging, as the prion is present in secretions and wastes of infected animals that remain infectious when deposited in the environment. CWD is highly transmissible, both through direct animal-to-animal contact and through indirect contact with a prion in the environment. In order to manage CWD in deer it is important to prevent them from contacting the prion by removing infected and sick deer from the population.

CWD was first detected in Wisconsin and Illinois in 2002. Prior to 2007, both states were able to manage the disease and sustain prevalence rates in free ranging deer herds below 2.0 percent, with prevalence defined as the proportion of infected animals out of all animals tested. After 2007, Wisconsin relaxed their CWD management program and lifted the deer-feeding ban except in areas where the disease had been detected, while Illinois continued both practices. Since 2007, overall CWD prevalence rates in Wisconsin have risen dramatically, but have remained steady in Illinois.

A biologist examining a harvested white-tailed deer.

Currently, Illinois conducts a targeted management program only in areas infected with CWD. Detection of hot spots of disease is a joint effort between Illinois Department of Natural Resources biologists and hunters who provide their deer for testing. Local control of CWD is achieved through focused reductions of deer numbers in infected areas and is possible with the support provided by hunters through the harvest of additional animals, and by landowners who allow access to IDNR staff for deer removals in these areas. This collaboration has resulted in a decrease in infected deer, a decrease in their contribution of infectious prions to the environment, and a decrease in the contact rates between infected and susceptible animals.

Participation by landowners and hunters in Illinois’ CWD management efforts demonstrates their commitment to protect the health of the deer herd and the public’s natural resource. The Illinois deer herd is a robust public natural resource where 85.7 percent of the adult females are pregnant, averaging twin litters, and where 20 percent of the fawns are pregnant. The Illinois deer herd is healthy, and its future rests in the hands of those trained and professionally educated to manage wildlife as a public natural resource and the citizens who reduce unnatural and artificial congregations of deer.

A white-tailed deer
Photo by Michael R. Jeffords

Illinois sustains a nationally recognized CWD management program based on collaborative efforts between citizens and wildlife professionals. This integrated approach facilitates adaptable processes to control CWD while benefiting the hunting community and citizens of Illinois. The commitment to management and control of CWD should be sustained in order to allow scientific knowledge to advance and continue to develop additional strategies to manage this disease.

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The Illinois deer herd is a robust public natural resource where 85.7 percent of the adult females are pregnant, averaging twin litters.

Dr Nohra Mateus-Pinilla, is a Veterinarian with a PhD in Veterinary Epidemiology and Preventive Medicine working at the Illinois Natural History Survey of the University of Illinois – Prairie Research Institute. She advises Postdoctoral Research Associates, graduate and undergraduate students at the University of Illinois in Champaign-Urbana. Dr Mateus conducts research on infectious diseases of critical impact to the health of humans, wildlife, domestic and agricultural animals. She has more than 15 years of experience conducting research in the transmission dynamics and critical control points in the management of Chronic Wasting Disease. Her work is published in peer reviewed journals and is available on her website. Dr Mateus works with local communities to understand the impacts of infectious diseases on the citizens of Illinois and their public natural resources.

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