Scrapie

Scrapie is a fatal, degenerative disease that affects the nervous systems of sheep and goats. It is one of several Transmissible spongiform encephalopathies (TSEs), which are related to Bovine spongiform encephalopathy (BSE, or "mad cow disease") and Creutzfeldt–Jakob disease (CJD) in humans.

History

Scrapie has been known since 1732, and does not appear to be transmissible to humans. The name "scrapie" is derived from the Norwegian word skraper, which means "to scrape". It was first scientifically described in 1938.

Symptoms

Scrapie is characterised by itching and rubbing against fixed objects, caused by damage to the nervous system. Other symptoms include weight loss despite retention of appetite, abnormal behaviour, tremors, and changes in gait.

Transmission

Scrapie is believed to be caused by a type of protein known as a prion. Prions are able to reproduce by converting normal proteins into the disease-associated form. Scrapie is transmitted primarily through the ingestion of placenta or placental fluids from infected animals.

Diagnosis

Scrapie can be diagnosed by examining the brain tissue of deceased animals. A test known as the Western blot can be used to detect the presence of the abnormal prion protein.

Treatment and control

There is currently no cure for scrapie. Control measures include selective breeding for resistance to the disease, and the culling of infected animals.

See also

• Prion
• Transmissible spongiform encephalopathies
• Bovine spongiform encephalopathy
• Creutzfeldt–Jakob disease

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  Prion subdomain colored secondary structure