Prions cause many forms of encephalitis, or brain disease, such as scrapie, chronic wasting disease, Creutzfeldt-Jakob Disease, bovine spongiform encephalopathy and kuru. Prions work by changing the shape of proteins in infected animals. While normal proteins have lots of alpha helices, or twisted parts, changed proteins have lots of beta sheets, or flat parts. It has also been suggested that Alzheimer's disease causes damage to the prions. 