Epidemiological parameters for scrapie outbreaks in 30 sheep flocks.

*breeds are: Black Welsh Mountain (BWM); Brecknock Hill Cheviot (BHC); Charollais (Cha); Cheviot (C); Finn Dorset (FD); Friesland (F); Gotland (G); Lleyn (L); North Country Cheviot (NCC); North of England Mule (NEM); Poll Dorset (PD); Roussin (R); Shetland (Sh); Swaledale (Swa); Texel (T); Welsh Mountain (WM).†purebred (P), commercial (C) or mixed purebred and commercial (PC).‡purchased (P), homebred (H); the origin of the remaining of cases is unknown.