Mad Cow Disease (Creutzfeldt-Jacob disease, Transmissible Spongiform Encephalopathy; New variant CJD)

What is Mad Cow Disease?

Mad Cow Disease or Creutzfeldt-Jacob disease (CJD) is a disorder causing slowly progressive dementia and loss of movement. CJD is caused by prions (proteinaceous infectious particles). There are four forms of CJD - sporadic, iatrogenic, familial and new variant CJD.

Sporadic CJD is the most common form of CJD.

In familial CJD there is an inherited mutation in a gene which causes CJD.

In iatrogenic CJD the disease is transmitted by procedures such as transplantation of contaminated tissue (e.g. corneas) or contact with contaminated medical devices (e.g brain electrodes).

New variant CJD (nvCJD) is presumed to have been caused by ingestion of beef products contaminated with Bovine Spongiform Encephalopathy (BSE) or "mad cow disease".

Statistics on Mad Cow Disease?

The total worldwide incidence of CJD is 1 per million people. The majority of cases are sporadic CJD, and familial CJD accounts for 10% of cases. Variant CJD (which is linked with Bovine Spongiform Encephalopathy or "mad cow disease"), was first noted in Britain in 1995 and its incidence continues to increase. Over 100 cases of variant CJD have been reported in the United Kingdom.

Risk Factors for Mad Cow Disease

Family history of CJD

Transmission may occur in cases of corneal transplantation, administration of human pituitary-derived hormones and use of contaminated surgical instruments.

Ingestion of infected beef containing the prions that cause Bovine Spongiform Encephalopathy.

Progression of Mad Cow Disease

The mean duration of sporadic CJD is 8 months while new variant CJD and familial CJD have slightly longer courses. CJD is progressive and invariably leads to death. Early symptoms are neuropsychiatric, followed by ataxia, and dementia with myoclonus or chorea. Late complications include:

Infection

Heart failure

Respiratory failure

Loss of ability to function or care for oneself

Loss of ability to interact with others

Side effects of medications used to treat the disorder (see the specific medication)

How is Mad Cow Disease Diagnosed?

An EEG (electroencephalograph, a reading of electrical activity of the brain) will show characteristic changes of CJD if the symptoms have been present for at least 3 months. The EEG will also show periodic paroxysms of spikes on a slow background. Though not diagnostic, presence of certain proteins in the spinal fluid is highly suggestive of CJD, when accompanied by other characteristic symptoms. MRI may show brain shrinkage and abnormal signals in part of the brain.

Prognosis of Mad Cow Disease

The prognosis for CJD is poor. Dementia commonly occurs within 6 months of the onset of symptoms, with the person losing the ability to care for themselves. Death occurs usually within 8 months, but a few people may survive as long as 1 or 2 years after diagnosis of the disorder. The cause of death is usually infection, heart failure, or failure of breathing.

How is Mad Cow Disease Treated?

There is no known cure for Creutzfeldt-Jacob disease. Custodial care may be required early in the course of the disease. There is a need to provide a safe environment, control aggressive or agitated behaviour, and meet physiologic needs which may require monitoring and assistance in the home or in an institutionalized setting. Family counseling may help in coping with the changes required for home care.Legal advice may be appropriate early in the course of the disorder, to form advance directives, power of attorney, and other legal actions that may make it easier to make ethical decisions regarding the care of an individual with Creutzfeldt-Jacob disease, as the patient themselves may not be capable of making decisions as the disease progresses.

Mad Cow Disease References

Advisory Committee on Dangerous Pathogens/Spongiform Encephalopathy Advisory Committee (1998) Transmissible Spongiform Encephalopathy Agents; Safe Working and the Prevention of Infection. London: The Stationery Office.
Hankey G., Wardlaw J. Clinical Neurology. Demos Medical Publishing, United Kingdom, 2002.