Creutzfeldt-Jakob disease (CJD). Computer artwork based on a light micrograph of a section through a human brain exhibiting CJD. Cell bodies of brain neurones (dark red) are surrounded by many white gaps or vacuoles. These are caused by the CJD prion, a virus-like protein. There are three types of CJD: the first appears, apparently without cause, in elderly people; the second affects those who have had transplants from infected people and the third, new variant CJD, is thought to be caused by eating cattle infected by the disease, bovine spongiform encephalopathy (BSE). The symptoms include dementia and myoclonus (sudden muscular contractions). Death occurs within two to three years.