Creutzfeldt-Jakob disease (CJD) is a rare neurological illness (disease of the nervous system) that causes damage to the brain.
It belongs to a group of diseases called transmissable spongiform encephalopathies, or prion diseases, that affect humans and animals.
CJD is fatal, and there is no known cure. It is caused by an abnormal protein called a prion that contaminates the nervous system.
Prions
Prions are infectious particles made of abnormally folded protein. In some respects, a prion is similar to a virus as it can replicate and cause disease. But unlike a virus, it is made entirely from protein and has no genetic material.
This makes prions much 'tougher' than viruses or bacteria: they can survive extremes of heat and radiation and are resistant to being broken down by enzymes that normally control the body's protein levels. Antibiotic and antiviral medicines have no effect on them.
Prions kill brain cells and make holes in the brain, causing it to become sponge-like. See Causes for more information.
Types of CJD
There are four different types of CJD, which each have a different cause:
- Sporadic CJD (sCJD) - the most common form, accounting for 85% of CJD cases. In 2009, 59 people died of sCJD in the UK. The cause is unknown, but it normally affects people aged over 40.
- Variant CJD (vCJD) - first identified in 1996, vCJD is caused by eating meat from cattle infected with BSE ('mad cow disease'). vCJD mainly affects people in their twenties. The number of cases peaked in 2000 and are now declining. There were two confirmed deaths from vCJD in the UK in 2009 and other suspected cases.
- Iatrogenic CJD (iCJD) - this is the result of the infection being spread from someone with CJD through medical or surgical treatment. Nowadays, cases are extremely rare: there was only one death from iCJD in the UK in 2009.
- Inherited prion disease (IPD) - this rare form of prion disease is caused by inheriting a faulty gene that produces prions. There were four deaths from IPD in the UK in 2009.
For more information, see the Causes page.
All cases of CJD are carefully monitored by the National CJD Surveillance Unit and the NHS National Prion Clinic (see Useful links, right).
Outlook
There is no cure for CJD and the condition causes you to deteriorate rapidly, to the point where you are no longer able to care for yourself and cannot move or speak.
Most people with sporadic CJD die within six months of diagnosis, often from pneumonia. People with variant CJD live for an average of just over a year.
