Scrapie is a fatal contagious disease of sheep and goats that causes degeneration of the central nervous system. Scrapie is contracted early in life and is believed to be transmitted from dams to offspring primarily through contact with afterbirth, but other means of transmission can not be ruled out. Although it may require years for clinical signs to appear, the disease is always fatal. Scrapie is estimated to cost the sheep industry of the United States more than $20 million each year. Although the disease does affect goats, few cases have ever been identified in this species in the U.S. Most cases of scrapie in the U.S. have occurred in black-faced sheep breeds. USDA-APHIS has developed an eradication program designed to eliminate the disease by 2010 and have the U.S. declared scrapie-free by 2017.
Although scrapie is in the same family of diseases as Bovine Spongiform Encephalopathy, there is no evidence it spreads to humans.
Scrapie is believed to be caused by a sub-viral protein particle which, after gaining entry to the body, commandeers protein synthesis processes in brain cells. This causes production of massive sheets of abnormal protein that crowd out and destroy normal brain tissue.
Scrapie is found worldwide except in Australia and New Zealand.
There is no evidence scrapie is a public health threat.
Until recently, diagnosis depended on post mortem identification of spongiform degeneration of the brain. However, ante mortem diagnostic tests involving immunological cells in tissues near the eye and in rectal mucosa have been developed and approved.
The introduction of scrapie into a herd may be prevented by allowing into the herd only animals from certified scrapie-free flocks. Entry and spread of the disease may also be prevented by bringing into the herd only rams and by maintaining highly sanitary conditions during lambing, including immediately removing and disposing of placentas. Sheep producers can conduct genetic testing and select for sheep with genotypes QR or RR at codon 171; individuals with genotype QQ at this genetic location have greater tendencies to develop clinical signs of scrapie. No such genetic selection tool is currently available for goats.