Atypical scrapie in sheep from a UK research flock which is free from classical scrapie

Simmons, Hugh A., Simmons, Marion M., Spencer, Yvonne I., Chaplin, Melanie J., Povey, Gill, Davis, Andrew, Ortiz-Pelaez, Angel, Hunter, Nora, Matthews, Danny and Wrathall, Anthony E. (2009) Atypical scrapie in sheep from a UK research flock which is free from classical scrapie. BMC Veterinary Research, 5 . doi:10.1186/1746-6148-5-8


Author Simmons, Hugh A.
Simmons, Marion M.
Spencer, Yvonne I.
Chaplin, Melanie J.
Povey, Gill
Davis, Andrew
Ortiz-Pelaez, Angel
Hunter, Nora
Matthews, Danny
Wrathall, Anthony E.
Title Atypical scrapie in sheep from a UK research flock which is free from classical scrapie
Journal name BMC Veterinary Research   Check publisher's open access policy
ISSN 1746-6148
Publication date 2009-02
Sub-type Article (original research)
DOI 10.1186/1746-6148-5-8
Open Access Status DOI
Volume 5
Total pages 9
Place of publication London, United Kingdom
Publisher BioMed Central
Language eng
Formatted abstract
Background: In the wake of the epidemic of bovine spongiform encephalopathy the British government established a flock of sheep from which scrapie-free animals are supplied to laboratories for research. Three breeds of sheep carrying a variety of different genotypes associated with scrapie susceptibility/resistance were imported in 1998 and 2001 from New Zealand, a country regarded as free from scrapie. They are kept in a purpose-built Sheep Unit under strict disease security and are monitored clinically and post mortem for evidence of scrapie. It is emphasised that atypical scrapie, as distinct from classical scrapie, has been recognised only relatively recently and differs from classical scrapie in its clinical, neuropathological and biochemical features. Most cases are detected in apparently healthy sheep by post mortem examination.
Results: The occurrence of atypical scrapie in three sheep in (or derived from) the Sheep Unit is reported. Significant features of the affected sheep included their relatively high ages (6 y 1 mo, 7 y 9 mo, 9 y 7 mo respectively), their breed (all Cheviots) and their similar PRNP genotypes (AFRQ/AFRQ, AFRQ/ALRQ, and AFRQ/AFRQ, respectively). Two of the three sheep showed no clinical signs prior to death but all were confirmed as having atypical scrapie by immunohistochemistry and Western immunoblotting. Results of epidemiological investigations are presented and possible aetiologies of the cases are discussed.
Conclusion: By process of exclusion, a likely explanation for the three cases of atypical scrapie is that they arose spontaneously and were not infected from an exterior source. If correct, this raises challenging issues for countries which are currently regarded as free from scrapie. It would mean that atypical scrapie is liable to occur in flocks worldwide, especially in older sheep of susceptible genotypes. To state confidently that both the classical and atypical forms of scrapie are absent from a population it is necessary for active surveillance to have taken place.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ
Additional Notes Article # 8

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Veterinary Science Publications
 
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Created: Thu, 03 Sep 2009, 08:30:03 EST by Mr Andrew Martlew on behalf of School of Veterinary Science