What is Creutzfeldt-Jakob Disease (CJD)?
Prion diseases are a group of rare, invariably fatal brain disorders which occur both in humans and certain animals. They first came to public attention in the mid 1980s in the form of the BSE epidemic in the United Kingdom. BSE (bovine spongiform encephalopathy) is a prion disease in cattle. Tissue from infected animals may have contaminated cattle feed, leading to the silent spread of the BSE epidemic. There is also a theory that BSE came from feed contaminated with scrapie, the long established sheep prion disease. Inevitably, concern over whether BSE could pass to humans mounted.
In humans, the best known prion disease is Creutzfeldt-Jakob Disease (CJD), first documented in 1920 by two German doctors, Hans Gerhard Creutzfeldt (1885-
1964) and Alfons Maria Jakob (1884-1931). CJD reportedly affects approximately one person per million per population each year worldwide. In the United States (U.S.), this translates to approximately 300 new cases annually. It is well known that CJD is very difficult to diagnose, leading to speculation that the one case per million statistics may be incorrect. Most of the cases are sporadic CJD (sCJD), occurring for no, as of yet, proven reason. The sporadic form accounts for approximately 85% of the cases. The familial form of CJD (fCJD) is associated with a genetic mutation that is passed on from parent to child. fCJD accounts for approximately 10-15% of the cases. The third type of CJD is acquired by infection from an outside source; there are at least three types of acquired CJD:
1. Kuru – Acquired through cannibalism
2. Iatrogenic CJD (iCJD) – Acquired through contaminated surgical instruments or tissue transplants
3. Variant CJD (vCJD) – Exposure to BSE contaminated meat
The main indications leading to a possible diagnosis of CJD are rapid dementia and one or many of a range of neurological symptoms including unsteady gait,
hallucinations and sudden jerking movements. The brains of people and animals infected with a prion disease show characteristic damage known as spongiform
changes. When seen under a microscope, the brain tissue shows many tiny holes almost like a sponge. For this reason, prion disease is known as spongiform
encephalopathy, although the term prion disease is preferred. Most prion diseases are transmissible in the laboratory, although the infectious agent is not a conventional bacterium or virus. Instead, the infectivity is associated with an abnormal protein or prion. Because prions are so unusual and prion diseases are unique in that they can both be inherited and transmitted, the area has attracted enormous scientific and medical interest. This provides a ray of hope that all of this attention may one day lead to a cure.
What are the Symptoms of Sporadic CJD?
Sporadic CJD usually comes “out of the blue,” although the pattern of symptoms may vary from person to person.
• In the “typical” subtype of sporadic CJD (sCJD M/M 1), early symptoms are often like those of depression, mood swings, memory lapses, social withdrawal
and lack of interest. However, rapid progression to dementia and obvious neurological symptoms distinguish CJD from depression.
• Within weeks, the patient may become unsteady on their feet, lacking in coordination and markedly clumsy. This pattern of symptoms is clinically known as cerebellar ataxia because it is caused by damage to the cerebellum, the part of the brain which controls movement. In some people, these are the first symptoms.
• Later symptoms may include blurred vision, hallucinations, blindness, rigidity in the limbs, sudden jerking movements and incontinence.
• Speech may become more difficult or slurred. Swallowing may become difficult.
• Eventually, the patient loses the ability to move or speak and will require full time nursing care. In this state, clinically known as akinetic mutism, the patient may appear to be following what is going on around them, but in fact they may not be aware of their surroundings.
Most patients die within a few months of onset of symptoms, some within a few weeks. Other subtypes can linger for several years.
In some subtypes, the first clinical signs may affect movements, often resulting in unsteady gait rather than dementia
Causes of CJD
- Genetic mutation inherited from a parent
- Contaminated surgical instruments
- Contaminated dura mater transplant
- Contaminated corneal transplant
- Contaminated human growth hormone
- Contaminated beef
- Contaminated blood or blood plasma transfusion
Diagnosis of CJD is very difficult and is often made from clinical observation and/or process of elimination of other diseases. The diagnosis of CJD can only be confirmed through a brain biopsy or autopsy. Cerebral spinal fluid testing positive for a 14-3-3 or tau protein is often used to confirm a possible diagnosis, this test, however, can be ambiguous.
Public Health Concerns
CJD is NOT “Mad Cow Disease.” Bovine Spongiform Encephalopathy (BSE), the technical term for Mad Cow Disease, occurs only in cows.The first documented case of BSE found in the United States occurred in Washington State in December 2003 in a cow imported from Canada. The first endemic case was found in Texas and was announced in 2005. Eating infected beef is widely believed to be the cause of the variant form of CJD (vCJD) in humans. vCJD usually affects young people. An endemic case has not yet been documented as originating in the United States.Is the public at risk of exposure to CJD? Although most Americans have never heard of Creutzfeldt-Jakob Disease, they have heard of “Mad Cow Disease” and fear it. They do not know what it is, but know it is catastrophic. The confirmation of a case of vCJD originating in the U.S. would likely lead to a chain reaction of panic-driven decisions and policymaking.
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