Chapter 7 : Transmissible Spongiform Encephalopathies

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There are specific transmissible spongiform encephalopathies (TSEs) which affect humans and others which affect animals. Evidence suggests that bovine spongiform encephalopathy (BSE) has crossed the species barrier to cause variant Creutzfeldt-Jakob disease (vCJD) in humans. The primary focus of this chapter is on BSE and its assumed relationship with vCJD. The chapter also provides more detailed summaries on scrapie and chronic wasting disease (CWD). The clinical, pathological, and molecular genetic features of the transmissible spongiform encephalopathies have led to speculation on the nature of the etiologic agent and the pathogenic mechanisms of the disease. A transmissible spongiform encephalopathy has been diagnosed in eight species of captive wild ruminants as well as exotic (cheetahs, pumas, a tiger, and an ocelot) and domestic cats. Isolations from the distal ileum were made in experimentally infected calves that were 4 months old, at 10,14, and 18 months after dosing. This study has also identified infectivity in bone marrow, trigeminal ganglion, dorsal root ganglion, brain, and spinal cord. The diagnosis of BSE is based on the occurrence of clinical signs of the disease and currently is confirmed by postmortem histopathological examination of brain tissue. Due to the many unknowns surrounding CWD, much research is under way to better characterize the disease, determine host range, develop and validate diagnostic tests, and understand the epidemiology. The results of this work will assist in developing science-based methods for prevention and control.

Citation: Detwiler L, Rubenstein R, Williams E. 2000. Transmissible Spongiform Encephalopathies, p 131-159. In Brown C, Bolin C (ed), Emerging Diseases of Animals. ASM Press, Washington, DC. doi: 10.1128/9781555818050.ch7

Key Concept Ranking

Transmissible Spongiform Encephalopathies
Immune Systems
Chronic Wasting Disease
Prion Proteins
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Image of Figure 1
Figure 1

Number of confirmed cases of BSE in Great Britain by year of restriction, 1986 through 1999. The data include 46 cases that were not subject to official restrictions and were identified by proactive surveillance or at autopsy. Source: United Kingdom Ministry of Agriculture, Fisheries and Food.

Citation: Detwiler L, Rubenstein R, Williams E. 2000. Transmissible Spongiform Encephalopathies, p 131-159. In Brown C, Bolin C (ed), Emerging Diseases of Animals. ASM Press, Washington, DC. doi: 10.1128/9781555818050.ch7
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Image of Figure 2
Figure 2

Number of bovine brains submitted for BSE testing, by state, from 10 May 1990 through 31 March 2000. None tested positive for BSE. Source: National Veterinary Services Laboratory, APHIS, USDA.

Citation: Detwiler L, Rubenstein R, Williams E. 2000. Transmissible Spongiform Encephalopathies, p 131-159. In Brown C, Bolin C (ed), Emerging Diseases of Animals. ASM Press, Washington, DC. doi: 10.1128/9781555818050.ch7
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