Most affected people are older, and the source of the disease can rarely be found. There have been a few dozen cases of CJD in Great Britain which occurred in younger people, and which may have been related to the mad cow epidemic in that country. Aside from one other case in France, there have been no cases in other countries attributed to eating beef. Some experts don't even agree that the English cases in young people were transmitted through beef. CJD in humans causes a progressive dementia, marked by loss of memory, inability to understand others and to speak coherently, and by fatigue, insomnia, and a muscular jerkiness called myoclonus.
Seizures occasionally occur.
The disease progresses rapidly, that is, over a period of months rather than years, and is invariably fatal. There is no accepted treatment. The diagnosis of CJD can be difficult, since scans of the brain are not very specific, and even the spinal fluid often does not show any changes. In some cases a brain biopsy will prove the diagnosis, but many cases of the disease are not diagnosed until after death, by autopsy examination of the brain. This is one doctor who makes housecalls.