Wednesday, December 26, 2007

Chronic Wasting Disease

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) of deer and elk that has occur only surrounded by limited areas surrounded by the Western United States. First recognized as a clinical syndrome in 1967, it is typified by chronic mass loss leading to departure. There is no known relationship between CWD and any other spongiform encephalopathy of animals or associates.


CWD has occur in animals at one jailbird wildlife research facility in northern Colorado and one within southeastern Wyoming. Although cases of CWD have be seen within two zoological parks more than 10 years ago, the affected animals adjectives originated from the research services in the above-mentioned areas. Soon after diagnosis of the disease as a TSE, Colorado and Wyoming wildlife direction agencies stopped the movement of deer and elk from these facilities. CWD have been confirmed contained by free-ranging deer and elk in a limited number of counties surrounded by northeastern Colorado and southeastern Wyoming. CWD has also be diagnosed in several farm elk herds within South Dakota, one in Nebraska, and one within Oklahoma.


Species that have be affected beside CWD are Rocky Mountain elk, mule deer, white-tailed deer, and black-tailed deer. Other ruminant species, including wild ruminants and domestic cattle, sheep, and goats, hold been housed surrounded by wildlife facilities within direct or indirect contact with CWD-affected deer and elk. No cases of CWD or other TSE's enjoy been detected contained by these other ruminant species. There is ongoing research to further explore this possibility.


Clinical Signs


Most cases of CWD occur contained by adult animals. The disease is progressive and other fatal. The most plain as the nose on your face and consistent clinical sign of CWD is weight loss over time. Behavioral change also occur within the majority of cases, including decreased interactions beside other animals in the pen, listlessness, lowering of the director, blank facial expression, and repetitive walking in set patterns inwardly the pen. In elk, behavioral changes may also include hyperexcitability and diffidence. Affected animals continue to put away grain but may show decrease interest in hay. Excessive salivation and grinding of the teeth are seen. Most deer show increased drinking and urination.


Diagnosis


Research is self conducted to develop live-animal diagnostic tests for CWD. Currently, definitive diagnosis is base on necropsy examination and carrying out tests. Gross lesions see at necropsy reflect the clinical signs of CWD, primarily emaciation and aspiration pneumonia, which may be the exact of death. On microscopic nouns, lesions of CWD surrounded by the central fearful system resemble those of other spongiform encephalopathies. In addition, using a technique call immunohistochemistry, scientists test brain tissues for the presence of the protease-resistant prion protein.


Epidemiology


The place of birth and mode of transmission of CWD is unknown. Animals born within captivity and those born in the windy have be affected next to the disease. Based on epidemiology of the disease, transmission is thought to be lateral and possibly loving. Transmission by feed is not believed to turn out as affected animals own been feed a wide group of feedstuffs.


Colorado and Wyoming wildlife management agencies are continuing to invest resources in CWD research hard work. In addition, the Colorado Division of Wildlife is currently developing a organization plan for CWD in free-ranging cervids. These agencies are committed to limiting the distribution of the disease to the current localized nouns and decreasing its occurrence within the deer and elk population.


Surveillance


Surveillance for CWD in Colorado and Wyoming have been ongoing since 1983, and to date, have confirmed the limits of the endemic areas contained by those States. An extensive nationwide surveillance try was started within 1997-98 to better define the geographic distribution of CWD. This surveillance action is a two-pronged approach consisting of hunter-harvest cervid surveys conducted in Arizona, Colorado, Idaho, Kansas, Michigan, Montana, Nebraska, Nevada, New Jersey, South Dakota, Utah, and Wyoming, as well as surveillance throughout the entire country target deer and elk exhibiting clinical signs suggestive of CWD.


In the free-ranging population, from over 5,000 samples examined, within have be approximately 110 clinically affected deer and elk identified over the finishing 10 years. The majority of those affected be mule deer. Again, there enjoy been no free-ranging animals found to be positive that did not spring from the endemic areas.

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