Creutzfeldt-Jakob disease

Creutzfeldt.jpg

Creutzfeldt-Jakob disease or CJD is a devastating illness. The disease often affects individuals, often in prime of health, aged 40 to 80 years. Although considered to be a rare disease, our experience is that there are 3 to 4 cases per year in a city of 250,000 suggesting an incidence of 1 per 100,000. According to support groups that are following patients with CJD, this is a more reasonable figure than the 1 per million espoused by government agencies. Nevertheless, there is danger of occurrence of the disease in epidemic proportions because of spread in wild animal populations.

The disease spectrum: CJD is the human form of the transmissible spongiform encephalopathies, which include scrapie in sheep and goats, transmissible mink encephalopathy, bovine spongiform encephalopathy (BSE) or mad cow disease, and chronic wasting disease (CWD) in deer and elk. These conditions are all caused by a presumably related group of transmissible agents.

This group of diseases were not considered important until the outbreak of BSE in Britain and Europe. Scrapie had long been known to be endemic in England, but was not a financial burden to the sheep industry since animals were killed during the incubation period. Unfortunately, scrapie-infected tissues were ground into bone meal and fed to cattle with the subsequent occurrence of BSE. The practice of feeding BSE-infected cattle to other cattle by the same process resulted in appearance of a virulent strain of the transmissible agent through serial passage. This virulent form has leaped into humans as new variant form of CJD that was able to cause disease in teenagers. Realization of this ability of the transmissible agent to cross species barriers has led to new respect for CJD and has raised the possibility of a future epidemic.

Diagnosis:

This is a very important question since there is a 35% error in clinical diagnosis. Other conditions such as brain gliomas, lymphomas or degenerative brain diseases can produce the same clinical signs and symptoms. The workup of these patients includes non-specific studies such as radiological imaging studies. The electroencephalogram tends to be positive late in the course of the disease. Although most clinicians rely on the 14-3-3 spinal fluid test, this test in unreliable, being present in only a small window of clinical disease. Currently, the only reliable means of making a definitive diagnosis of CJD is by brain biopsy or autospy.

Infection source:

The source of infection in most cases of CJD is unknown and thus the term sporadic. We do know of instances of transmission through use of contaminated instruments at surgery, corneal transplant tissues, dura grafts, growth hormone from necropsy-derived pituitary glands etc. These forms of iatrogenic transmission of the disease are a real danger because often the patient may have been admitted and undergone a prior surgical procedure with no suspician of the oncoming CJD illness. We know that the incubation period for CJD transmitted by corneal transplant is at least 12 months so that potentially infected instruments may be used on many patients before the problem is realized. Another problem is the potential contamination of our blood supply since many patients who have died of CJD have been professional blood donors and had given blood only a few months before they died of CJD. Since the plasma from these patients are pooled, there is great danger that many individuals could be infected from a single CJD patient. Although there is conflicting data regarding infectivity of the blood from CJD patients experimentally, there has to be developed some way of screening for potential iatrogenic spread of the disease, either by tissue or blood products.

The evidence is compelling that a dietary source of the transmissible agent is the cause of occurrence of new variant CJD in Europe. Experimentally, lymphoid tissue along the gastrointestinal tract of scrapie-infected sheep indicates an oral route for scrapie infection. Experimental infection via the oral route indicates that the BSE agent is very potent when given by mouth. In addition, review of tissues from all members of flocks of sheep that have been killed because one animal came down with scrapie infection has revealed many more animals to be infected without clinical symptoms or signs. Therefore, currently, it is impossible to pinpoint a definite source of infection for this disease even if there is a relationship to food intake.

CJD cause:

At present the cause of CJD is unknown. My research has clearly shown that a bacterium, Spiroplasma, is involved. However, government support is mostly limited to the "prion concept" which suggests that a replicating protein is the cause. Although the prion is a phenomenon that occurs in CJD, it is likely a reaction product to the agent. Not only is the prion theory inconsistent with data regarding the nature of the infectious agent, it is not believable that an infectious protein could survive passage through the acidity of the stomach. The agent must have a nucleic acid core and be protected by a cell wall or membrane. The Spiroplasma concept fits all those criteria and there is direct evidence, exemplified by the documentation of Spiroplasma DNA in CJD tissues, that this bacterium is involved in the pathogenesis of the disease. Only time will tell if there is adequate funding to test all possible leads.

Danger of transmission:

The answer to that question is not known. We do know that the salivary gland is infectious in scrapie suggesting that certain secretions may be infectious. Nonetheless, the chance of transmission by contact has not been documented in human infection, although we have reported a husband/wife infection. Reasonable care must be used in preventing against potential infection of caring family members, but not to the extent of not caring for the patient. Wearing gloves when handling feces or cleanup would be advised. The use of chlorox in cleanup is suggested. Wash hands after each contact with the patient.

Unfortunately, there has been little attention to models of infection in the recent past that would answer this question. Furthermore, there is no reasonable test for the agent that could be applied to secretions, etc.

Treatment:

Currently, CJD is a fatal disease and there is no known therapy. However, there is recent evidence that experimental scrapie infection can be prevented by antibiotic treatment at time of inoculation, specifically using tetracyclines. These experiments are noteworthy in that they support the bacterial concept of causation. In addition, a recent study has shown response to anti-oxidants which is reasonable since products of oxidation are abundant in CJD-infected tissues. Spiroplasma thrive in the presence of the oxygen radical. Although these studies suggest therapies are possible, it will be important to develop a diagnostic test so that the patient can be identified early enough so that a therapeutic regimen can have a chance of success.

Image: portrait of Hans Gerhard Creutzfeldt who discovered the disease.

 
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