Changes

Diagnosis is confirmed on '''post-mortem''' and PrP^Sc can be isolated from brainstem or lymphoid tissues by Western immunoblot, immunohistochemistry (IHC) and [[ELISA testing|Elisa tests]]. Immunohistochemistry usually shows vacuolation and an accumulation of prion proteins in various parts of the CNS (medulla, pons, midbrain, and spinal cord). However vacuolation is not completely diagnostic since it may also be present to a lesser extent in the brains of healthy sheep <ref name="Fraser, 1976"> Fraser H (1976) '''The pathology of a natural and experimental scrapie. '''''Frontiers of Biology,'' 44:267-305.</ref>, <ref name="Zlotnik and Rennie, 1958"> Zlotnik I, Rennie JC (1958) '''A comparative study of the incidence of vacuolated neurones in the medulla from apparently healthy sheep of various breeds.''''' Journal of Comparative Pathology,'' 68:411-415.</ref>. In most instances the abnormal prion is resistant to protein kinase digestion, a feature used in diagnostic techniques. IHC staining of tonsil and lymphoid biopsies have been used for preclinical scrapie testing and the third eyelid lymphoid tissue can be used for diagnosis in sheep.  

Diagnosis is confirmed on '''post-mortem''' and PrP^Sc can be isolated from brainstem or lymphoid tissues by Western immunoblot, immunohistochemistry (IHC) and [[ELISA testing|Elisa tests]]. Immunohistochemistry usually shows vacuolation and an accumulation of prion proteins in various parts of the CNS (medulla, pons, midbrain, and spinal cord). However vacuolation is not completely diagnostic since it may also be present to a lesser extent in the brains of healthy sheep <ref name="Fraser, 1976"> Fraser H (1976) '''The pathology of a natural and experimental scrapie. '''''Frontiers of Biology,'' 44:267-305.</ref>, <ref name="Zlotnik and Rennie, 1958"> Zlotnik I, Rennie JC (1958) '''A comparative study of the incidence of vacuolated neurones in the medulla from apparently healthy sheep of various breeds.''''' Journal of Comparative Pathology,'' 68:411-415.</ref>. In most instances the abnormal prion is resistant to protein kinase digestion, a feature used in diagnostic techniques. IHC staining of tonsil and lymphoid biopsies have been used for preclinical scrapie testing and the third eyelid lymphoid tissue can be used for diagnosis in sheep.  

'''Differential diagnoses''':  

'''Differential diagnoses''':  

==Control==

==Control==

Good husbandry and hygiene around lambing can greatly reduce the infectious load. It is recommended that individual straw bale pens are used which can be destroyed after each lambing and that contaminated bedding and placenta should be removed immediately.   Infection can be minimised by maintaining a closed flock and only obtaining replacement ewes or breeding rams from scrapie-free flocks. Animals of resistant genotypes should be used for breeding to further minimize the risk of scrapie infection in a flock <ref name="CFIA, 2005">Canadian Food Inspection Agency, 2005. Scrapie. http://www.inspection.gc.ca/english/anima/heasan/man/scrtre/scrtree.shtml, Accessed 7 March 2005.</ref>, <ref name="Dawson et al., 1998">Dawson M, Hoinville LJ, Hosie BD, Hunter N, 1998. Guidance on the use of PrP genotyping as an aid to the control of clinical scrapie. Veterinary Record, 142(23):623-625.</ref>, <ref name="European Commission, 2001">European Commission, 2001. Commission Regulation (EC) No. 999/2001 of the European Parliament and of the Council of 22 May 2001 laying down rules for the prevention, control and eradication of certain transmissible spongiform encephalopathies. Official Journal of the European Communities, L 147:1-40.</ref>, <ref name="US Department of Agriculture, 2005"> USDA, 2005. Scrapie program. http://www.aphis.usda.gov/vs/nahps/scrapie/, accessed 7 March 2005.</ref>. Genetic resistance to scrapie depends on the prion genotype of the sheep and on the strain of scrapie present. Genotypes of sheep resistant to one strain of scrapie may be susceptible to another strain but on the whole the ARR allele confers resistance in all breeds. In 2001 the UK government set up the [http://animalhealth.defra.gov.uk/managing-disease/notifiable-disease/scrapie/national-scrapie-plan/ National Scrapie Plan NSP)] which aims to increase the frequency of the ARR allele within UK sheep population. Since 1988 it has been illegal for ruminant derived meat and bone meal to be fed to ruminants.

Good husbandry and hygiene around lambing can greatly reduce the infectious load. It is recommended that individual straw bale pens are used which can be destroyed after each lambing and that contaminated bedding and placenta should be removed immediately.  

 

Infection can be minimised by maintaining a closed flock and only obtaining replacement ewes or breeding rams from scrapie-free flocks. Animals of resistant genotypes should be used for breeding to further minimize the risk of scrapie infection in a flock <ref name="CFIA, 2005">Canadian Food Inspection Agency (2005) '''Scrapie'''. http://www.inspection.gc.ca/english/anima/heasan/man/scrtre/scrtree.shtml, Accessed 7 March 2005.</ref>, <ref name="Dawson et al., 1998">Dawson M, Hoinville LJ, Hosie BD, Hunter N (1998) '''Guidance on the use of PrP genotyping as an aid to the control of clinical scrapie.''''' Veterinary Record,'' 142(23):623-625.</ref>, <ref name="European Commission, 2001">European Commission (2001) '''Commission Regulation (EC) No. 999/2001 of the European Parliament and of the Council of 22 May 2001 laying down rules for the prevention, control and eradication of certain transmissible spongiform encephalopathies. '''''Official Journal of the European Communities,'' L 147:1-40.</ref>, <ref name="US Department of Agriculture, 2005"> USDA (2005) '''Scrapie program.''' http://www.aphis.usda.gov/vs/nahps/scrapie/, accessed 7 March 2005.</ref>. Genetic resistance to scrapie depends on the prion genotype of the sheep and on the strain of scrapie present. Genotypes of sheep resistant to one strain of scrapie may be susceptible to another strain but on the whole the ARR allele confers resistance in all breeds. In 2001 the UK government set up the [http://animalhealth.defra.gov.uk/managing-disease/notifiable-disease/scrapie/national-scrapie-plan/ National Scrapie Plan NSP)] which aims to increase the frequency of the ARR allele within UK sheep population. Since 1988 it has been illegal for ruminant derived meat and bone meal to be fed to ruminants.

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[[Category:Neurological Diseases - Sheep]][[Category:Neurological Diseases - Goat]]

[[Category:Neurological Diseases - Sheep]][[Category:Neurological Diseases - Goat]]

[[Category:Transmissible Spongiform Encephalopathies]]

[[Category:Transmissible Spongiform Encephalopathies]]

[[Category:To_Do_-_CABI review]]

[[Category:CABI Expert Review]]

[[Category:To Do - Major]]