Transmissible Spongiform Encephalopathies (TSE) or Prion Diseases
Page updated 9 October 2007
Transmissible Spongiform Encephalopathies (TSE) or Prion Diseases
Key Points |
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Patients with degenerative central nervous system disease without a clear diagnosis, or a likely diagnosis or proved CJD must not have any invasive disease procedure, especially endoscopy, without telling the Infection Control Team.
CJD is a family of diseases with long incubation periods characterised by degenerative brain disease.
The brain pathology is similar. There is an accumulation of abnormal prion protein in the central nervous system.
Classical prion disease has been transmitted in pituitary tissue, dura mater grafts and corneal grafts.
The diseases are species constrained though there is a possibility that animal disease can be transmitted to man in food. Variant Creutzfeldt Jakob Disease (vCJD), analogous to bovine spongiform encephalopathy (BSE), is clinically different from classical CJD.
Because the "agent" is a very stable protein (prion) rather than a virus or bacterium, it is not inactivated by normal sterilisation methods.
Report cases of suspected or known TSE to the Infection Control Team and CCDC
Instruments used in CSF sampling and brain biopsy must be disposable because vCJD is found in lymphoid tissues such as tonsils, instruments used for procedures such as tonsillectomy should be disposable.
Special endoscopes (used, for example, for PEG tube insertion) should be reserved only for patients with these conditions. |
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1.0. Introduction
The Transmissible Spongiform Encephalopathies are rare conditions caused by abnormal folding of a protein in the brain. This abnormal protein is able to cause disease when inoculated into animals. These transmissible agents are called prions (Protein Infectious agent) and the "infectivity" cannot be inactivated by the usual methods of killing "living" organisms (sterilisation and disinfection).
CJD is Recognised in Four Forms
Classical (cCJD) is divided into:
- Familial (fCJD) is associated with a family history in a first degree relative.
- Sporadic (sCJD) occurs with no known risk factors for other forms.
- Iatrogenic (iCJD) is associated with exposure to contaminated tissues or instruments from a known case of CJD.
Variant (vCJD) is:
- Causally associated with the epidemic of BSE in cattle and is clinically and pathologically different from cCJD.
The TSE/prion diseases include Creutzfeldt-Jakob Disease (CJD), scrapie of sheep, bovine spongiform encephalopathy (BSE) manifest as variant CJD in man, and kuru (restricted to members of the Fore Tribe, Papua-New Guinea.
Sporadic prion disease is most commonly seen as a rapidly progressive dementia in elderly patients.
Some diseases are inherited (eg Gerstmann-Straussler-Scheinkler syndrome (GSS) and fatal familial insomnia (FFI). 10-15% of cases represent the inherited forms of prion disease, which are transmissible in animal models. Inherited prion disease is diagnosed on the basis of an abnormality of prion protein gene analysis and there is often, though not always, a family history of neurodegenerative disease. The commonest presentation of inherited prion disease is a progressive ataxic syndrome or progressive cognitive impairment.
The pathological process is a slow one with progressive neurological disease following a very long incubation period. Each of these diseases have rather different clinical presentations, although the eventual outcome is always a fatal global cortical degeneration.
Prions elicit no detectable immune response and are resistant to the usual methods of decontamination.
