What Is Creutzfeldt-Jakob Disease?
Creutzfeldt-Jakob Disease ("CJD") is a rare, fatal brain disorder which causes a rapid, progressive dementia and associated neuromuscular disturbances. The disease is often referred to as a subacute spongiform encephalopathy because it usually produces microscopic vacuoles in neurons that appear "sponge-like".
Who Can Be Stricken By Creutzfeldt-Jakob Disease?
Creutzfeldt-Jakob Disease can afflict anyone. The disease affects both men and women of diverse ethnic backgrounds usually between the ages of 50 to 75 years. Reports indicate that the disease occurs worldwide, with an incidence of one case per million people each year.
What Causes Creutzfeldt-Jakob Disease?
Scientists recognize that a transmissible agent is responsible for causing Creutzfeldt-Jakob Disease, as shown by experiments involving the injection of CJD-affected brains into the normal brains of healthy animals. The identification of this transmissible agent has been the subject of much scientific inquiry and debate.
Virus Or Prion
Initially, the agent was thought to be a slow virus due to the unusually long incubation period between the time of exposure to the pathogen and the onset of symptoms. Further research, however, has indicated that this agent differs significantly from viruses and other conventional agents. Whereas viruses and other known infectious agents contain nucleic acids which house a cell's genetic material, researchers have been unable to identify any nucleic acids in the CJD agent. Additionally, the chemical and physical procedures that inactivate most viruses have proved ineffective in decreasing the infectivity of the CJD pathogen. In contrast, the procedures that degrade protein have been found to inactivate the pathogen. Accordingly, a new theory regarding the transmissible agent has emerged and recently gained widespread acceptability. This theory holds that the transmissible agent is neither a virus nor other previously known infectious agent, but rather an unconventional agent consisting of protein. This newly-discovered pathogen is called a "prion", short for " proteinaceous infectious particle". Prions are thought to transform normal, benign protein molecules into infectious, deadly ones by altering the shape of the healthy molecules to the dangerous conformation.
Other Diseases Caused By Similar Agents
Prions are believed to be responsible for other fatal brain diseases in humans, as well as animals. In addition to CJD, the suspected human prion diseases include kuru, Gerstmann-Straussler-Scheinker disease and fatal familial insomnia. Kuru has been found only among the Fore tribe in Papua New Guinea and has been virtually eliminated since the cessation of the ritual handling and eating of the brains of deceased relatives. The disease is characterized by progressive problems with coordination which are typically followed by dementia. Gerstmann-Straussler-Scheinker disease and fatal familial insomnia are predominantly hereditary disorders with the former usually marked by progressive coordination and movement problems and the latter evidenced by sleeping problems preceding dementia. The suspected prion diseases occurring in animals consist of: scrapie in sheep and goats; transmissible mink encephalopathy; chronic wasting disease of mule deer and elk; feline spongiform encephalopathy; and, bovine spongiform encephalopathy ("BSE"), also known as "mad cow disease".
How Does One Get Creutzfeldt-Jakob Disease?
There appear to be three general categories for classifying the means through which CJD may be acquired. First, the disease can occur sporadically. Second, the disease can be inherited. Third, the disease can be transmitted through infection.
Sporadic Creutzfeldt-Jakob Disease
Sporadic CJD refers to those cases in which there is no known infectious source and no evidence of the disease in the prior or subsequent generations of the patient's family. Most CJD cases occur sporadically, thereby leaving their origins a mystery.
Inherited Creutzfeldt-Jakob Disease
Approximately 10 to 15 per cent of CJD cases are inherited. These familial cases exhibit a mutation in the gene coding for the prion protein. Genetic factors are thought to be responsible for the elevated numbers of CJD cases in some communities in Czechoslovakia and Chile, as well as among Libyan-born Jews.
Creutzfeldt-Jakob Disease Through Infection
Although CJD is caused by a transmissible agent, the disease is not considered to be contagious in the traditional sense. The spouses and family members who live with CJD patients appear to have no greater risk of getting the disease than the general population. Very few cases of CJD have been shown to have originated from exposure to an infected individual.
At the present
time, the only proven manner for contracting CJD from an infected person
has been through iatrogenic transmission, an unintended consequence of
a medical procedure using tainted human matter or surgical instruments.
Iatrogenic transmission of CJD has occurred in cases involving corneal
transplants, implantation of electrodes in the brain, dura mater grafts,
contaminated surgical instruments and the injection of natural human growth
hormone derived from cadaveric pituitaries. Thus, one may become infected
with CJD from direct contamination with infected neural tissue.
Although CJD has been found in such health care professionals as neurosurgeons, dentists, nurses, histopathology technicians and a pathologist, there has been no proof establishing that the professional was infected by a particular patient. Nevertheless, the risks posed by the handling of infectious material mandate that health care workers strictly follow the guidelines and precautions developed by scientists for treating CJD patients and handling their tissues, fluids and other contaminated materials.
The issue of whether there is a direct link between the exposure to diseased animals and the acquisition of CJD has been the subject of much scientific study and debate. In Britain, scientists and politicians have struggled to ascertain if there is a connection between bovine spongiform encephalopathy ("BSE") and CJD. BSE or "mad cow disease" was initially discovered in Britain in 1986 and thought to have resulted from the use of cattle feed containing ground offal from scrapie-infected sheep. Although the rate of BSE has declined from its peak of 900 to 1000 cases per week in 1992 and 1993, there were still between 280 to 300 cases per week reported in January 1996. Meanwhile, the incidence of CJD in Britain, though still small, has increased, nearly doubling between 1990 and 1994. Recently, on March 20, 1996, the British Government, in a complete reversal of its previous position, stated that there was a possible link between BSE and CJD. This new acknowledgement arose from the identification of an apparently new strain of CJD which was discovered in 10 people under the age of 42, including some teenagers. Additionally, five of the people were associated with the meat and livestock industry. Scientists advising the British Government decided that the most likely explanation for this unusual outbreak was the consumption of beef from diseased cattle before 1989, when regulations were adopted for the disposal of potentially infectious cattle offal, including brains, and the use of sheep entrails as feed ceased.
What Are The Symptoms of Creutzfeldt-Jakob Disease?
There are several common symptoms evident in CJD patients as the disease runs its course. The duration of CJD from the onset of symptoms to the inevitable death is usually one year; however, shorter duration periods of several months are common, and longer duration periods of two or more years have been noted, usually in the familial form and with an earlier age of onset.
The initial stage of the disease can be subtle with ambiguous symptoms of insomnia, depression, confusion, personality and behavioral changes, strange physical sensations, and problems with memory, coordination and sight. As the disease advances, the patient experiences a rapidly, progressive dementia and in most cases, involuntary and irregular jerking movements known as myoclonus. Problems with language, sight, muscular weakness, and coordination worsen. The patient may appear startled and become rigid. In the final stage of the disease, the patient loses all mental and physical functions. The patient may lapse into a coma and usually dies from an infection like pneumonia precipitated by the bedridden, unconscious state.
How Is Creutzfeldt-Jakob Disease Diagnosed?
A diagnosis of CJD should be considered when an adult patient develops a rapid dementia and myoclonus. Unfortunately, confirming a diagnosis of CJD has historically been difficult as traditional laboratory tests have been ineffective in detecting CJD. The disease does not induce a fever or other systemic manifestations. The cerebrospinal fluid most often appears normal, except for an occasional elevation in the protein content. Magnetic resonance imaging ("MRI"), position emission tomography ("PET"), and x-rays have not been helpful in diagnosing CJD. A computed tomography ("CT") brain scan is usually normal, but may show some atrophy, a nondiagnostic finding seen in many other neurological conditions. The most helpful test has been the electroencephalogram ("EEG"), which measures brain wave activity. The EEG often shows a characteristic abnormal pattern, typically observed in later stages of the disease, but the EEG does not confirm a CJD diagnosis.
Accordingly, a definitive diagnosis of CJD has traditionally required a brain biopsy or autopsy which can detect the characteristic changes in the brain tissue caused by the disease. Moreover, a brain biopsy may sometimes produce a false-negative result if the biopsied area was unaffected by the disease. At the present time, however, a new test is being developed to diagnose CJD by examining the cerebrospinal fluid. Additional tests proposed to confirm a diagnosis of CJD include identifying the presence of the deadly prion protein, identifying the prion gene mutation, and transmitting the disease from the human patient to animals.
The difficulties involved in diagnosing CJD may have prevented the indentificaton of the disease in some cases. Because brain biopsy for diagnosing CJD is invasive, costly and risky, it is often not performed. Additionally, some physicians may not even consider the possibility of a CJD diagnosis since the disease is deemed to be rare and the clinical symptoms of CJD can often be attributed to other ailments. Consequently, CJD may be mistaken for a variety of psychological illnesses and other neurological disorders like Alzheimer's disease, Pick's Disease, Huntington's Disease, cerebral hematomas and vascular irregularities. The extent to which such misdiagnosis may have occurred is presently unknown.
Is There Any Treatment Or Cure For Creutzfeldt-Jakob Disease?
At the present time, there is no known effective treatment or cure for CJD. The disease is inevitably fatal.
Is Research Currently Being Conducted On Creutzfeldt-Jakob Disease?
Yes. Government agencies and public and private institutions around the world are engaged in researching all aspects of CJD. The current crisis in Britain involving BSE and CJD is expected to generate a great deal of research.
What Organizations Can Be Contacted For Further Information On Creutzfeldt-Jakob Disease?
For additional information on CJD, contact the following organizations:
Disease Foundation, Inc.
P.O. Box 611625
North Miami, Fl. 33261-1625
of Neurological Disorders and Stroke
National Institutes of Health
31 Center Drive MSC 2540
Bethesda, Md. 20892-2540
(301) 496-5751 or (800) 352-9424
For Rare Disorders (NORD)
P.O. Box 8923
New Fairfield, Ct. 06812-1783
Creutzfeldt-Jakob Disease, Office of Scientific and Health Reports, National Institute of Neurological and Communicative Disorders and Stroke, NIH Pub. No. 86- 2760 (May 1986).
Scientific and Medical Publications
Bailes B. Creutzfeldt-Jakob Disease: A Fatal Neurodegenerative Transmissible Disorder. AORN Journal. 1990;52:976-985.
Bendheim P. Creutzfeldt-Jakob Disease, in Cecil Textbook of Medicine (Wyngaarden J., Ed.), 18th ed.,vol.2, W.B. Saunders Co. Harcourt Brace Jovanovich, Inc., 1988; 2205-2206.
Berger JR, David NJ. Creutzfeldt-Jakob disease in a physician: A review of the disorder in health care workers. Neurology 1993; 43:205-206.
Brown P, Cathala F, Raubertas RF, Gajdusek DC, Castaigne P. The epidemiology of Creutzfeldt-Jakob disease: conclusion of a 15-year investigation in France and review of the world literature. Neurology 1987; 37:895-904.
Davanipour Z, Smoak C, Bohr T, Sobel E, Liwnicz B, Chang S. Death Certificates: An Efficient Source for Ascertainment of Creutzfeldt-Jakob Disease Cases. Neuroepidemiology 1995;14:1-6.
Hsiao K, Prusiner SB. Inherited human prion diseases. Neurology 1990; 40:1820-1827.
Pendlebury WW. Central Nervous System Diseases Caused By Unconventional Transmissible Agents and Chronic Viral Infections, in The Neurological Disorders (Bradley WG, Ed.), vol.2, Butterworth-Heineman, Boston, 1991; 1112-1116.
Prusiner SB. The Prion Diseases. Scientific American. Jan. 1995; 48-57.
Rosenberg RN, White CL III, Brown P, Gajdusek C, Volpe J, Posner J, Dyck PJ. Precautions in handling tissues, fluids, and other contaminated materials from patients with documented or suspected Creutzfeldt-Jakob disease. Annals of Neurology 1986; 19:75-77.
Webb RM, Leech RW, Brumback RA. Spongiform Encephalopathies: The Physician's Responsibility. Southern Medical Journal. 1990; 83:141-145.
Altman L. "Mad Cow Epidemic Puts Spotlight on Human Brain Disease". The New York Times, April 2, 1996, at p. B8.
Altman L. " U.S. Confident On Mad Cow Disease". The New York Times, March 27, 1996, at p. A8.
Bowditch G. "Girl of 15 becomes youngest victim of CJD". The Times (London), April 27, 1996 (Internet Edition-General News).
"Britain: Fatal human illness, cattle disease may be linked". The Miami Herald, March 21, 1996, at p.18A.
Cookson, C. " Evidence grows of CJD link with meat". Financial Times, March 21, 1996, at p. 7.
Cookson C, Hargreaves D. " Evidence links BSE to humans". Financial Times, March 21, 1996 at p. 1.
Darnton J. " Britain Ties Deadly Brain Disease to Cow Ailment". The New York Times, March 21, 1996, at p. A1.
Darnton J. " London Adamant as European Union Bans British Beef". The New York Times, March 26, 1996, at p. A3.
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