Neuropathology 2000

Abstracts for Meetings

S06-4

Chronic Wasting Disease in Cervids

Williams, E[1]; Miller, MW[2] [1]University of Wyoming, USA; [2]Colorado Division of Wildlife, USA.

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) of captive and free-ranging mule deer (Odocoileus hemionus), white-tailed deer (O. virginianus), and elk (Cervus elaphus nelsoni) in portions of North America. It was recognized as a clinical syndrome in captive deer in the late1960s but likely was present in the wild prior to that time. The neuropathology of CWD resembles scrapie and BSE. Lesions in clinically affected cervids are relatively consistent and characterized by widespread vacuolar degeneration of neurons and spongiform change in the neuropil with severe lesions in the parasympathetic vagal nucleus, thalamus/hypothalamus, and olfactory cortex. Florid plaques are most common in white-tailed deer, rare in mule deer, and have not been recognized in elk. Immunohistochemistry at the level of the obex is critical for diagnosis of subclinical CWD; in a large survey of deer in the CWD endemic area of Colorado and Wyoming, USA only about 50% of deer positive for PrPres accumulation in the parasympathetic vagal nucleus had spongiform encephalopathy. In studies of the pathogenesis of CWD in orally inoculated deer and elk, immunohistochemistry demonstrated accumulation of PrPres in the parasympathetic vagal nucleus by 6 months post-inoculation in some infected animals. This was 6 months to a year prior to development of spongiform change and onset of clinical disease.