The cerebellum has many functions, such as controlling gait and coordination. GSSD patients have difficulties maintaining balance. Fatal familial insomnia first manifests as difficulty sleeping, bu t patients soon develop dementia and ultimately die. Many mammals get prion diseases, including mink, squirrels, elk, deer, and cats. The best known example is scrapie in sheep.
Affected sheep lose coordination and become irritable.
In the 1970s, British farmers used ground offal from dead sheep to feed cattle -after which the cattle began to exhibit symptoms similar to those of the affected sheep. In 1988, the British government banned the practice of feeding cattle with infected sheep. However, an unknown number of people had a lready eaten potentially contaminated beef. The epidemic of mad cow disease probably peaked in 1992-93, when up to 1,000 cases per week were reported. In January 1996, there were still about 300 cases a week.