History
In 1967, Chronic Wasting Disease was first noticed among mule deer at a wildlife research facility in Colorado. Some modeling has been done suggesting that the disease may have been present in free-ranging populations of mule deer for more than 40 years. After CWD was found, it was subsequently observed in wild and captive deer and elk in several other U.S. states as well as in Canada. Only four species of the deer family, Cervidae, are known to be naturally susceptible to CWD: mule deer, white-tailed deer, Rocky Mountain elk, and moose. The origin of CDW is not known and it may never be possible to positively identify when and how CDW arose. Determining the origin is not very important from a management perspective, nonetheless, speculation continues. Some theories suggest that CWD may have derived from scrapie, a transmissible spongiform encephalopathy (TSE) of domesticated sheep. Scrapie has been recognized in the United States since 1947. It is possible, although never proven, that deer came into contact with the scrapie agent either on shared pastures or in captivity somewhere along the front range of the Rocky Mountains, where in the early 1900’s, ranchers used these lands for high levels of sheep grazing.
Wisconsin has been monitoring its white-tailed deer for disease since the 1990s, starting with bovine tuberculosis. The surveillance program was expanded in 1999 to include CWD. Hunters voluntarily submit samples from culled deer, which are tested at the National Veterinary Services Laboratories in Ames, Iowa. More than a thousand deer were tested in that time, all with negative results. But on Feb. 28, Wisconsin officials were notified that three submissions from the 2001 hunting season had tested positive for CWD. The infected deer had been killed in western Dane and eastern Iowa counties, and 11 additional infections were later discovered that area. How CWD was introduced in Wisconsin and the number of infected are not known.
CWD was first reported east of the Mississippi River in Wisconsin among white-tailed deer harvested in the 2001 hunting season. Subsequent surveillance indicated that this CWD epidemic focus was limited to several counties in the south-central region of Wisconsin, although a second focus spanning the Illinois border was also detected. The discovery of CWD in southern Wisconsin represents a significant threat to the state's white-tailed deer population and the culture of deer hunting in the state. Wisconsin has more than 700,000 deer hunters who have harvested an average of 460,000 deer annually during the past decade. Deer hunting contributes more than 7 million days of recreation each year. Deer hunting annually generates more than $500 million dollars in retail sales and nearly $1 billion in total impact to the state’s economy.
There are consequences to not attempting to control the disease or an inadequate response: the prevalence and geographic distribution of CWD will increase and there will be long-term impacts on the deer hunting culture of Wisconsin and related industries and businesses. The results of ongoing research studies are needed to better understand the dynamics of the disease, its pattern of increase and spread, the role of environmental transmission, and the effect of management actions on the disease.