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 through contact with afterbirth. 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, very 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 breeds. USDA-APHIS has developed an eradication program designed to eliminate the disease by 2010.
Although scrapie is in the same family of diseases as Bovine Spongiform Encephalopathy, there is no evidence it spreads to humans.
Causative Agent
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 causing the production of massive sheets of abnormal protein, which crowd out and destroy normal brain tissue.
Endemic Areas
Scrapie is found worldwide except in Australia and New Zealand.
Clinical Signs
- Behavior changes
- Rubbing or biting of wool or skin
- Progressive incoordination
- High stepping or bunny hopping gait
- Weakness
- Weight loss despite good appetite
- Hypersensitivity to noise
- Head and neck tremors
- Lip smacking (especially in goats)
Diagnosis
Until recently, diagnosis depended on identifying spongiform degeneration of the brain post mortem. However, antemortem diagnostic tests involving immunological cells in tissues near the eye and in rectal mucosa have been developed and approved.
Treatment
There is no treatment for scrapie. Any animal suspected of having scrapie should be reported to the State Veterinarians or USDA Area Veterinarian in Charge immediately.
Prevention
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.
Public Health
There is no evidence Scrapie is a public health threat.
Links
- Scrapie Program -USDA-APHIS
- Eradicate Scrapie -National Institute for Animal Agriculture
- About Scrapie -AVMA
- Factsheet -Ohio State University Veterinary Preventative Medicine
