Ovine scrapie. New tools for control of an old disease

Ovine scrapie was described nearly 300 years ago and is endemic in many parts of the world. The recent emergence of a related bovine disease in the United Kingdom and Europe, with probable transmission to humans, has lent urgency to scrapie surveillance and control programs. The biology, genetics, diagnosis, and proposed routes of transmission can be understood in the context of the presumed causative agent, the prion protein. An integrated program of management and husbandry to reduce introduction and spread of the disease within a flock, diagnosis of preclinically infected sheep in both live animal and postmortem settings, and identification of breeding stock of low risk of scrapie are reviewed as the basis for scrapie eradication programs.