Beware the Shape-shifter:
The threat across the pond
"Could this happen to us?" This is the question facing officials and hunters in North America in light of an emerging disease in deer and elk.
Eleven U.S. states (Colorado, Illinois, Kansas, Minnesota, Montana, Nebraska, New Mexico, Oklahoma, South Dakota, Wisconsin, and Wyoming) and two Canadian provinces (Alberta and Saskatchewan) have reported cases of chronic wasting disease (CWD), a prion disease that causes progressive weight loss, excessive salivation and urination, and inevitable death.
Affecting wild and captive mule deer, white-tailed deer and Rocky Mountain elk, CWD is endemic in northern Colorado and southern Wyoming. Scientists have recognized CWD as a clinical syndrome for more than 30 years, but the disease may have been present in free-ranging deer populations for more than 40 years. One thing that's clear is that CWD is a highly contagious disease, particularly in captive settings.
Telling has partnered with Colorado State University and recently received a $2.6 million share of a seven-year, $8.4 million grant from the National Institute of Allergy and Infectious Diseases, part of NIH. Colorado State's portion will fund an emerging disease research center, in Fort Collins, focused on CWD. This is one of seven centers supported by NIH in a new push to explore emerging infectious diseases.
The Colorado Department of Wildlife facility in Fort Collins has been at the center of CWD research for a number of years. "We know that deer and elk that are introduced into the Fort Collins facility develop CWD at a very high rate," Telling says. "But we don't know exactly how." Scientists speculate bodily fluids like saliva or urine may transmit the disease, and animals that are confined have a greater chance of exposure to other animals. Efforts to sanitize the facility have been unsuccessful.
Shipping deer and elk across state lines for breeding purposes has most likely played a role in the spread of CWD. And it's possible that efforts such as Kentucky's aggressive program to reestablish a free-ranging elk herd in Eastern Kentucky, which started in 1997, may have brought the disease to the Bluegrass. No deer or elk in Kentucky have been diagnosed with CWD, but elk were imported from two states (Kansas and Nebraska) currently battling the disease.
Telling has discussed strategy with the Kentucky Department of Fish and Wildlife Resources, and, according to Jonathan Gassett, wildlife division director, that department, in cooperation with the Kentucky Department of Agriculture and the Kentucky Alternative Livestock Association, created regulations in July 2002 to protect the state from possible CWD infection. In November, Kentucky Governor Paul Patton issued an executive order placing a temporary moratorium on the import or export of deer and elk. Gassett says deer and elk resources in Kentucky contribute more than $300 million annually to the state's economy through hunting, wildlife viewing and employment related to those activities.
When the CWD threat came to light, hunters were told not to eat organs known to harbor prions, like the brain, spinal cord, tonsils, eyes, spleen, and lymph nodes; and they were warned to wear rubber gloves when processing animal carcasses.
"We don't know if this disease can transmit to other animals, in particular livestock that share pastures with deer and elk in the West," Telling says. "Could CWD cross the species barrier to create a BSE-like disease in cattle or a scrapie-like disease in sheep? And more importantly, we don't know anything about whether this disease will cause problems in humans, and this is a particularly important question in light of the emergence of new variant CJD in Europe.
"The stakes are a lot higher than 15 to 20 years ago," he says. "The CDC, USDA and NIH are very concerned about this disease because they don't want a mad cow epidemic on their hands."
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