Two Positive Results for Chronic Wasting Disease are First for Free-Ranging Deer in Missouri
The Missouri Department of Conservation (MDC) received two positive test results for Chronic Wasting Disease (CWD) from 1,077 tissue samples taken from free-ranging deer harvested by hunters in north-central Missouri during the 2011 fall firearms deer season. Both positive test results were from adult bucks harvested by Missouri hunters in Macon County, and are the first CWD-positive results for free-ranging deer in Missouri.
MDC plans to obtain more tissue samples for CWD testing by harvesting additional deer in the immediate area where the two infected deer were harvested.
“Teamwork among landowners, hunters and MDC staff allowed us to detect this infection early,” said MDC Deer Biologist Jason Sumners. “We will be working with local landowners to harvest additional deer for tissue sampling. This is a first step and one of our best hopes for containing, and perhaps even eliminating, what we believe to be a recent localized event.”
MDC staff have contacted the two Missouri hunters who harvested the CWD-positive bucks to inform them of the situation and answer questions.
CWD is a neurological disease that is limited to deer, elk, moose and other members of the deer family, known as “cervids.” CWD is spread by animal-to-animal contact or by animal contact with soil that contains prions from urine, feces or the decomposition of an infected animal. Deer and other cervids with signs of CWD show changes in natural behavior and can exhibit extreme weight loss, excessive salivation, stumbling and tremors. CWD can spread through natural movements of infected animals, transportation of infected live captive animals, or the transportation of infected carcasses.
The Missouri Department of Agriculture (MDA) says there is no evidence from existing research that CWD can spread to domestic livestock, such as sheep or cattle. The Missouri Department of Health and Senior Services (MDHSS) says there is no scientific evidence that CWD is transmissible to humans through contact with or the consumption of deer meat.
MDC conducted its tissue-sampling effort during the fall firearms season in November in response to two cases of CWD found in captive white-tailed deer at two private, captive-hunting preserves in Linn and Macon counties. A third captive deer at one of the preserves tested positive for CWD in December. The two earlier cases of CWD found at the private hunting preserves were detected in February 2010 and October 2011. The two free-ranging bucks that tested positive were harvested within two miles of the Macon County preserve.
CWD in deer can only be confirmed by laboratory testing of the brain stem or lymph tissue. Tissue samples collected by MDC were tested by the Southeast Cooperative Wildlife Disease Study Laboratory of the University of Georgia, Athens, with confirmation by the National Veterinary Services Laboratory in Ames, Iowa.
The disease was first recognized in 1967 in captive mule deer in Colorado. CWD has also been documented in both captive and free-ranging deer in neighboring Kansas and Nebraska. It has been documented in free-ranging deer in neighboring Illinois. CWD has also been documented in both captive and free-ranging members of the deer-family in Colorado, Minnesota, New York, South Dakota, Wisconsin and the Canadian provinces of Alberta and Saskatchewan. Maryland, New Mexico, North Dakota, Utah, Virginia, West Virginia and Wyoming also have documented cases of CWD in free-ranging members of the deer family. Michigan and Montana have documented cases of CWD in captive members of the deer family.
CWD is transmitted through prions, which are abnormal proteins that attack the nervous systems of these species. These prions accumulate in the brain, spinal cord, eyes, spleen, and lymph nodes of infected animals. While there is no scientific evidence that CWD is transmissible to humans or animals other than deer and other cervids, health officials caution that consumption of these parts is not recommended. They also advise people to not eat meat from animals known to be infected with CWD or that exhibit signs of any disease.
While CWD is new to free-ranging deer in Missouri, MDC has been testing for it for years. With the help of hunters, MDC has tested more than 34,000 free-ranging deer for CWD from all parts of the state since 2002.
Missouri also has a Cervid Health Committee to address the threat of CWD to Missouri’s free-ranging and captive cervids. The Committee is composed of wildlife biologists, veterinarians and other animal-health experts from MDC, MDA, MDHSS and the USDA.