CWD have been found is referred to as the endemic area. CWD has also been 

 identified in free-ranging deer and elk in Wisconsin, Illinois, New Mexico, South 

 Dakota, and Utah. 



At press time [April 2005], CWD had been found in 13 States. In eight of those, it 

 has been found in wildlife (Colorado, Illinois, New Mexico, North Dakota, South 

 Dakota, Utah, Wisconsin, and Wyoming). CWD has been diagnosed in four States in 

 farmed cervid herds and wild populations (Colorado, Nebraska, South Dakota, and 

 Wisconsin). Nine States have CWD in farmed cer\ id herds; of those, six States have 

 cleaned up their diseased herds while three (Colorado, New York, and Wisconsin) 

 still have positive farmed herds. 



Species that have been affected with CWD include Rocky Mountain elk, mule 

 deer, white-tailed deer, and black-tailed deer. Other rLuiiinaut species, including 

 wild ruminants and domestic cattle, sheep, and goats, have been housed in wildlife 

 facilities in direct or indirect contact with CWD-affected deer and elk. No cases of 

 CWD have been detected in these other ruminant species. 



Like the causative agents of scrapie and BSE, the agent responsible for CWD has not 

 been completely characterized. The CWD agent is thought to be an abnormal prion 

 protein. It is smaller than most viral particles and does not evoke any detectable 

 immune response or inflammatory reaction in the host animal. On the basis of 

 experience with other TSE agents, the CWD agent is assumed to be resistant to 

 enzymes and chemicals that normally break down proteins as well as to heat and 

 normal disinfection procedures. 



Clinical Signs — Most cases of CWD occur in adult animals. The disease is 

 progressive and always fatal. The most obvious and consistent clinical sign of CWD 

 is long-term weight loss. Behavioral changes also occur in the majority of cases, 

 including decreased interactions with other animals in the pen, listlessness, lowering 

 of the head, blank facial expression, and repetitive walking in set patterns within the 

 pen. In elk, behavioral changes may also include hyperexcitability and nervousness. 

 Affected animals continue to eat grain but may show decreased interest in hay. 

 Victims salivate excessively and grind their teeth. Most deer show increased drinking 

 and urination. 



Testing — Research is being conducted to develop live-animal diagnostic tests for 

 CWD. Currendy, definitive diagnosis is based on IHC testing of the obex area of 

 the brain stem or the medial retropharyngeal lymph nodes. Gross lesions seen at 

 necropsy reflect the clinical signs of CWD, primarily emaciation and sometimes 

 aspiration pneumonia, which may be the cause of death. On microscopic examination, 

 lesions of CWD in the central nervous system resemble those of other spongiform 

 encephalopathies. At this time, abnormal prion proteins are detected using IHC, 



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