Changes

==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" />, <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.  The UK government control programme (National Scrapie Plan or NSP) was launched in 2001 and proposes to increase the frequency of the ARR allele in the UK sheep population <ref name="DEFRA, 2001"></ref>.  Many countries use a combination of genetic selection, depopulation of infected sources and sourcing scrapie free flocks to control the spread of scrapie <ref name="US Department of Agriculture, 2005"> Department for Environment Food and Rural Affairs, 2001. National scrapie plan for Great Britain. Schemes brochure. DEFRA, 1-28.</ref> and <ref name="Thorgeirsdottir et al., 2002">Thorgeirsdottir S, Georgsson G, Reynisson E, Sigurdarson S, Palsdottir A, 2002. Search for healthy carriers of scrapie: an assessment of subclinical infection of sheep in an Icelandic scrapie flock by three diagnostic methods and correlation with PrP genotypes. Archives of Virology, 147(4):709-722; 31 ref.</ref>

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" />, <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.  The UK government control programme (National Scrapie Plan or NSP) was launched in 2001 and proposes to increase the frequency of the ARR allele in the UK sheep population <ref name="DEFRA, 2001"/>.  Many countries use a combination of genetic selection, depopulation of infected sources and sourcing scrapie free flocks to control the spread of scrapie <ref name="US Department of Agriculture, 2005"> Department for Environment Food and Rural Affairs, 2001. National scrapie plan for Great Britain. Schemes brochure. DEFRA, 1-28.</ref>, <ref name="Thorgeirsdottir et al., 2002">Thorgeirsdottir S, Georgsson G, Reynisson E, Sigurdarson S, Palsdottir A, 2002. Search for healthy carriers of scrapie: an assessment of subclinical infection of sheep in an Icelandic scrapie flock by three diagnostic methods and correlation with PrP genotypes. Archives of Virology, 147(4):709-722; 31 ref.</ref>.

Meat- and bone meal-contaminated feeds have not been shown to be involved in scrapie transmission, but prohibiting the use of feeds that contain ruminant animal products in sheep and goats is a prudent measure. In the UK, a feed ban was issued in 1988 prohibiting the feeding of ruminant-derived meat and bone meal to ruminants (HMSO, 2002) and was adopted by the EU in 1994 and USA in 1997 <ref name="European Commission, 2001" />; <ref name="FDA, 1997"> Food and Drug Administration, 1997. 21 CFR Part 589 [Docket No. 96N–0135] RIN 0910–AA91 substances prohibited from use in animal food or feed; animal proteins prohibited in ruminant feed. DHHS, 30935-30978.</ref>.

BSE in cattle has been linked to the practice of incorporating rendered ruminant byproducts into cattle feed. Meat and bone meal(MBM)contaminated feeds have not been shown to be involved in scrapie transmission, but prohibiting the use of feeds that contain ruminant animal products in sheep and goats is a prudent measure. In the UK, a feed ban was issued in 1988 prohibiting the feeding of ruminant-derived meat and bone meal to ruminants (HMSO, 2002) and was adopted by the EU in 1994 and USA in 1997 <ref name="European Commission, 2001" />, <ref name="FDA, 1997">Food and Drug Administration, 1997. 21 CFR Part 589 [Docket No. 96N–0135] RIN 0910–AA91 substances prohibited from use in animal food or feed; animal proteins prohibited in ruminant feed. DHHS, 30935-30978.</ref>.

   

   

==References==

==References==