Chronic wasting disease (CWD) is receiving attention in several states and in Canada. The disease, which affects elk, mule deer and white-tailed deer, was first observed in Colorado in 1967 and, until recently, was thought to be confined to north-eastern Colorado, southeastern Wyoming and western Nebraska. Since the late 1990s, however, chronic wasting disease, more familiarly known as CWD, has been found in deer and elk in 10 states and two Canadian provinces.
As part of its ongoing monitoring of the health of the state's wildlife, the Department of Conservation last year began testing Missouri deer for this disease. The 72 deer tested included any obviously sick or emaciated deer reported to conservation agents or offices. No CWD was found in Missouri.
The Missouri Department of Agriculture also tested elk brought into Missouri from an infected Colorado captive herd. None of the elk tested had CWD.
Because the disease has been found in other states, the Conservation Department is increasing its efforts to monitor Missouri deer for chronic wasting disease. This fall, the Department will test 6,000 deer - 200 from each of 30 randomly selected counties. The remaining counties will be sampled in 2003 and 2004. The sampling is designed to detect CWD, even if it exists in a small percentage of the state's deer herd.
Hunters who bring deer to check stations in selected counties during the November firearms deer season will be asked to voluntarily donate the heads of their deer for later testing by a federally approved laboratory. Removing the deer heads will only take a few minutes. Hunters will be able to keep the antlers from bucks. Testing, which involves examining the animal's brain, will be completed in about three to four months. Overall results will be posted on the Conservation Department's website for anyone interested in the sampling effort.
Chronic wasting disease belongs to a class of diseases known as transmissible spongiform encephalopathies (TSEs). Scrapie, which affects sheep and has been documented since the 1700s, is probably the most familiar of these diseases. Like other TSEs, CWD destroys nerve cells. The brain becomes sponge-like over time as nerve cells are affected. The disease is presumed to be fatal to deer and elk. Symptoms appearing during later stages of chronic wasting disease include a listless posture (with heads and ears drooping), weight loss, excessive thirst and salivation and frequent urination.
It's not yet clear how CWD is transmitted. One theory focuses on a durable strand of protein, known as a prion. Although not considered highly infectious, prions may nevertheless be transmitted from animal to animal by frequent direct or indirect contact. This helps explain why the disease was first noticed among confined animals. Some deer seem immune to CWD, suggesting that genetic susceptibility may vary among animals.
Prions are believed to be species-specific. They seem only able to function in the species in which they originated or within small groups of closely related species.
A World Health Organization (WHO) panel of experts and the Missouri Department of Health have reviewed available information on CWD and stated that there is no evidence that CWD infects humans.
Since the disease was discovered more than 30 years ago, no illnesses or deaths related to CWD among the nation's 16 million deer hunters have been found. It hasn't affected domestic livestock either. CWD has only affected deer and elk.
It's prudent to safeguard yourself when handling any kind of meat. The Conservation Department consistently recommends that hunters not shoot or process any deer that is obviously sick, and that they protect themselves from any diseases or parasites deer may carry by wearing rubber gloves while gutting a deer. Prions have not been found in the muscle tissue, or "meat," of CWD-infected deer. Instead, prions seem to be concentrated in an infected animal's brain and spinal cord.
Keeping Missouri's deer herd healthy has always been a primary goal of the Conservation Department. That's why the agency is working with Missouri's departments of Health and Agriculture, the captive cervid industry, hunters, taxidermists, meat processors and other groups to minimize the potential for CWD entering the Show-Me State.
On the national front, federal agricultural and wildlife officials are helping to coordinate a national approach to address CWD concerns, including educational and research efforts. Legislators are trying to work the provision into new legislation and hope to have funding in place some time in 2003.
Because of the remote possibility that CWD might already exist here undetected, the Conservation Department, like most Midwestern states, is stepping up its testing program. The tests should determine whether any CWD occurs in Missouri.
Missourians can help in the effort to control CWD by cooperating with the sampling program and reporting any obviously diseased deer.
Thanks to active management, Missouri's deer herd has rebounded from a few hundred animals in the early part of the 20th century to nearly a million animals today. Deer provide countless hours of viewing opportunity and sporting activity for Missourians, and venison sumptuously graces the tables of hunters' families. With the help of Missouri citizens and the efforts of our state's departments of Health, Agriculture and Conservation, we intend to keep it that way.
Approximately seven states were testing free-ranging herds prior to 1998. Fourteen states had begun testing for CWD by the year 2000. Currently, 37 states have some type of testing program to monitor free-ranging herds. As of October 2002, fewer than 300 free-ranging animals have tested positive for chronic wasting disease in the U.S.
|State||Began Testing||Year Found|
|Colorado||1981||1981 (elk and deer)|
|New Mexico||2000||2002 (deer)|
|South Dakota||1998||2001 (deer)|
|Wyoming||1981||1986 (elk and deer)|
Editor - Tom Cwynar
Managing Editor - Bryan Hendricks
Art Editor - Dickson Stauffer
Designer - Les Fortenberry
Artist - Dave Besenger
Artist - Mark Raithel
Photographer - Jim Rathert
Photographer - Cliff White
Staff Writer - Jim Low
Staff Writer - Joan McKee
Circulation - Laura Scheuler