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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Infectious Bacterial Diseases Research » Research » Publications at this Location » Publication #103036
Title: IMMUNOHISTOCHEMICAL DIAGNOSIS OF CHRONIC WASTING DISEASE IN PRECLINICALLY AFFECTED ELK FROM A CAPTIVE HERD

Author
item PETERS, J - UNIV.OF GA.,ATHENS,GA.
item JENNY, A - USDA-APHIS, AMES, IA.
item PETERSON, T - USDA-APHIS,RAPID CITY,SD.
item Miller, Janice

Submitted to: Wildlife Disease Association Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 8/10/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Chronic Wasting Disease (CWD) is a condition seen in captive and free-ranging cervids, including mule deer, white tailed deer, and Rocky Mountain elk. The disease is considered one of the Transmissible Spongiform Encephalopathies (TSE), a group of fatal diseases that affect the central nervous system and occur in several animal species, including human beings. The diagnosis of CWD has traditionally relied on observation of characteristic clinical signs or histopathologic changes in brain tissue. This report presents evidence that neither of these diagnostic strategies is sufficient for identification of some infected animals. An immunohistochemical (IHC) method was used to test brain tissues from 17 elk in a captive herd where CWD had previously occurred. The IHC technique detects a protein, the prion protein (PrP), that is considered a disease-specific marker for TSEs, regardless of the species affected. Of the 17 elk tested, 10 were found to be positive with the IHC test, whereas only 2 of the animals had shown clinical signs of CWD. Furthermore, only 3 animals, including both of the clinical cases, were definitely diagnosed as having the disease by histopathologic examination. Application of the IHC method to different areas of the brain showed that the most consistently positive tissue was medulla oblongata, especially a region known as the obex. These results clearly show that an IHC test on brain tissue, specifically medulla oblongata at the obex, is a more sensitive method than either clinical or histopathologic examination for diagnosing CWD. Therefore, the IHC test should be considered an essential component of any surveillance study intended to determine the incidence of CWD in captive or free-ranging cervids.