Creutzfeldt-Jakob disease


Updated April 2008

A progressive, degenerative disease of brain tissue due to an infection.

Creutzfeldt-Jakob disease (CJD) is an extremely rare condition in which brain tissue is progressively destroyed by an unusual infectious agent. CJD is a rapidly progressive disease of the nervous system which, in its classic form, affects middle-aged and older people causing death, usually within one year of onset. It has a very long incubation period often over 20 years. The disorder leads to a general decline in all areas of mental and physical ability and ultimately to death.

There are four forms of CJD - sporadic CJD, genetic CJD, iatrogenic CJD and variant CJD - each distinguished by cause of illness, symptoms and course of illness. The new variant of CJD (vCJD) with a shorter incubation period appeared in the late 1980s. It affected young people, mostly under 20, and the incubation period was obviously much shorter than in classical CJD. Sporadic cases of classical CJD continue to occur, most of them in people over 50. Since 1990, there have been 163 deaths related to vCJD and 1,267 related to all four types of CJD in the UK (as at 1 February 2008)[see reference 1].

Sometimes called subacute spongiform encephalopathy, CJD is an infection with an agent called a prion. This is not a germ, and it is not alive. It is a small protein molecule very similar to a protein necessary for normal brain function. There is clear evidence that this form is caused by the same strain of prion that causes ‘mad cow disease’ (bovine spongiform encephalopathy or BSE). Most experts currently believe that prions from sheep infected with scrapie crossed the species barrier to infect cattle and cause BSE. Meat products containing spinal cord and other nerve tissue mechanically recovered from cattle then entered the human food chain and caused vCJD.

Public health control measures, such as BSE surveillance, the culling of sick animals, or banning specified risk materials (SRMs), or a combination of these, have been instituted in Europe to prevent potentially BSE-infected tissue from entering the food chain. The most stringent of these control measures have been applied in the UK and appear to have been highly effective.

References:
  1. National Creutzfeldt-Jakob Disease Surveillance Unit - www.cjd.ed.ac.uk
Further information:

© British Medical Association 2008

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