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Creutzfeldt-Jakob Disease (CJD)


Image: CDC

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 in the brain of an abnormal form of the naturally occurring 'prion' protein.

CJD was initially described in its classical, or sporadic form, in 1920. A new variant known as variant CJD (vCJD) was first identified in 1996. Variant CJD is strongly linked to exposure, probably through food, to a TSE of cattle called Bovine Spongiform Encephalopathy (BSE).

BSE was first recognised as a separate disease entity in the UK in 1986. The disease agent is believed to be a scrapie-like agent (an infectious protein) that causes destruction of the grey matter in brain, leading to a progressive disease. The main clinical symptoms are hypersensitivity to external stimulus, lack of coordination, wasting and death. The disease has a long incubation period, from 2 to 8 years, and is mostly seen in adult cattle (youngest diagnosed animal 20 months). Stress appears to induce the symptoms in cattle, and many cases are diagnosed around calving and after transport.

It is currently believed that BSE originated from either sheep or cattle infected with a scrapie-like agent. Meat and bone meal made from infected animals was recycled back to susceptible cattle in feed, and infection followed. Changes in the processing of meat and bone meal in the early 1980s is believed to have allowed an increased infectivity build-up in the meal (Bradley, 2000). There is some evidence of maternal transmission of BSE to offspring, but it is suggested that this form of disease spread is not significant (Wilesmith et al., 1997). Other theories about the origin of BSE have been developed, suggesting that factors like organophosphorous dipping rendered some animals more susceptible to infection than others (Purdey, 1994).

Most (85%) cases of CJD are sporadic, with no known cause, and occur worldwide at a rate of about 1 case per million population per year. There are also inherited forms of CJD (10-15%) and those which have been acquired from another source.

Acquired CJD includes iatrogenic CJD and vCJD. Iatrogenic CJD is very rare, and occurs when CJD is accidentally transmitted during medical or surgical procedures. Although there have been no reported cases of vCJD having been transmitted as a result of surgical procedures, the possibility cannot be ruled out. Precautionary measures have been taken to reduce such a risk by improving the standards of decontamination services for surgical instruments.


Image: CDC

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 in the brain of an abnormal form of the naturally occurring 'prion' protein.

CJD was initially described in its classical, or sporadic form, in 1920. A new variant known as variant CJD (vCJD) was first identified in 1996. Variant CJD is strongly linked to exposure, probably through food, to a TSE of cattle called Bovine Spongiform Encephalopathy (BSE).

BSE was first recognised as a separate disease entity in the UK in 1986. The disease agent is believed to be a scrapie-like agent (an infectious protein) that causes destruction of the grey matter in brain, leading to a progressive disease. The main clinical symptoms are hypersensitivity to external stimulus, lack of coordination, wasting and death. The disease has a long incubation period, from 2 to 8 years, and is mostly seen in adult cattle (youngest diagnosed animal 20 months). Stress appears to induce the symptoms in cattle, and many cases are diagnosed around calving and after transport.

It is currently believed that BSE originated from either sheep or cattle infected with a scrapie-like agent. Meat and bone meal made from infected animals was recycled back to susceptible cattle in feed, and infection followed. Changes in the processing of meat and bone meal in the early 1980s is believed to have allowed an increased infectivity build-up in the meal (Bradley, 2000). There is some evidence of maternal transmission of BSE to offspring, but it is suggested that this form of disease spread is not significant (Wilesmith et al., 1997). Other theories about the origin of BSE have been developed, suggesting that factors like organophosphorous dipping rendered some animals more susceptible to infection than others (Purdey, 1994).

Most (85%) cases of CJD are sporadic, with no known cause, and occur worldwide at a rate of about 1 case per million population per year. There are also inherited forms of CJD (10-15%) and those which have been acquired from another source.

Acquired CJD includes iatrogenic CJD and vCJD. Iatrogenic CJD is very rare, and occurs when CJD is accidentally transmitted during medical or surgical procedures. Although there have been no reported cases of vCJD having been transmitted as a result of surgical procedures, the possibility cannot be ruled out. Precautionary measures have been taken to reduce such a risk by improving the standards of decontamination services for surgical instruments.

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