Creutzfeldt-Jakob disease (CJD) is a rare and ultimately fatal degenerative brain disease. It is one of a group of diseases called Transmissible Spongiform Encephalopathies (TSEs) that affect humans and animals. TSEs are thought to be caused by the build up of an abnormal form of the naturally occurring 'prion' protein in the brain.
CJD was initially described in its classical, or sporadic form, in 1920. Most (85%) cases of CJD are sporadic, with no known cause, and occur worldwide at an annual rate of about 1 case per million population. A further 10-15% of CJD cases are genetic or another form of inherited prion disease and are associated with mutations in the prion protein gene.
Rarer forms of human prion disease include acquired diseases such as Kuru and iatrogenic CJD. Iatrogenic CJD is very rare and occurs when CJD is accidentally transmitted as a result of medical or surgical exposures. Precautionary measures have been taken to reduce the risk of such exposures by implementing public health measures and improving the standards of surgical instrument and endoscope decontamination.
In 1996 a previously unrecognised form of the acquired disease was identified, now known as variant CJD (vCJD). Variant CJD is strongly linked to exposure to a TSE of cattle called Bovine Spongiform Encephalopathy (BSE), probably through consumption of contaminated beef and beef products.