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CJD:
Infection Control Practices |
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Questions
and Answers Regarding Creutzfeldt-Jakob Disease Infection-Control
Practices |
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What is Creutzfeldt-Jakob
disease?
Creutzfeldt-Jakob
disease (CJD) is a rapidly progressive, invariably fatal neurodegenerative
disorder believed to be caused by an abnormal isoform of a cellular glycoprotein
known as the prion protein. CJD occurs worldwide and the estimated annual
incidence in many countries, including the United States, has been reported
to be about one case per million population.
The vast
majority of CJD patients usually die within 1 year of illness onset. CJD
is classified as a transmissible spongiform encephalopathy (TSE) along
with other prion diseases that occur in humans and animals. In about 85%
of patients, CJD occurs as a sporadic disease with no recognizable pattern
of transmission. A smaller proportion of patients (5 to 15%) develop CJD
because of inherited mutations of the prion protein gene. These inherited
forms include Gerstmann-Straussler-Scheinker syndrome and fatal familial
insomnia.
How is CJD diagnosed?
Physicians
suspect a diagnosis of CJD on the basis of the typical signs and symptoms
and progression of the disease. In most CJD patients, the presence of
14-3-3 protein in the cerebrospinal fluid and/or a typical electroencephalogram
(EEG) pattern, both of which are believed to be diagnostic for CJD, have
been reported. However, a confirmatory diagnosis of CJD requires neuropathologic
and/or immunodiagnostic testing of brain tissue obtained either at biopsy
or autopsy.
Have there been any reports of iatrogenic transmission of CJD?
Yes, iatrogenic
transmission of the CJD agent has been reported in over 250 patients worldwide.
These cases have been linked to the use of contaminated human growth hormone,
dura mater and corneal grafts, or neurosurgical equipment. Of the six
cases linked to the use of contaminated equipment, four were associated
with neurosurgical instruments, and two with stereotactic EEG depth electrodes.
All of these
equipment-related cases occurred before the routine implementation of
sterilization procedures currently used in health care facilities. No
such cases have been reported since 1976, and no iatrogenic CJD cases
associated with exposure to the CJD agent from surfaces such as floors,
walls, or countertops have been identified.
How should surgical instruments used on suspected or confirmed CJD patients
be reprocessed?
Inactivation
studies have not rigorously evaluated the effectiveness of actual cleaning
and reprocessing methods used in health care facilities. Recommendations
to reprocess instruments potentially contaminated with the CJD agent are
primarily derived from in vitro inactivation studies that used either
brain tissues or tissue homogenates, both of which pose enormous challenges
to any sterilization process.
The World
Health Organization (WHO) has developed CJD infection
control guidelines that can be a valuable guide to infection control
personnel and other health care workers involved in the care of CJD patients.
Destruction of heat-resistant surgical instruments that come in contact
with high infectivity tissues, albeit the safest and most unambiguous
method as described in the WHO guidelines, may not be practical or cost
effective.
One of the
most stringent chemical and autoclave sterilization methods outlined in
Annex III of the WHO guidelines (see below) can be used to reprocess heat-resistant
instruments that come in contact with high infectivity tissues (brain,
spinal cord, and eyes) and low infectivity tissues (cerebrospinal fluid,
kidneys, liver, lungs, lymph nodes, spleen, and placenta) of patients
with suspected or confirmed CJD. High and low infectivity tissues were
defined on the basis of available experimental data as described in Table
2 of the WHO guidelines. The stringent sterilization methods described
below should be used to reprocess medical instruments that come in contact
with high infectivity tissues of persons known to be blood relatives of
patients with inheritable forms of TSEs.
What are the chemical and autoclave sterilization methods outlined in
Annex III of the WHO infection control guidelines for transmissible spongiform
encephalopathies?
The three
most stringent sterilization methods for heat-resistant instruments described
in Annex III of the WHO guidelines are listed below; the alternatives
are listed in order of more to less severe treatments. Sodium hypochlorite
may be corrosive to some instruments, such as gold-plated instruments.
Before instruments are immersed in sodium hypochlorite, the instrument
manufacturer should be consulted about the instrument's tolerance of exposure
to sodium hypochlorite.
- Immerse
in a pan containing 1N sodium hydroxide (NaOH) and heat in a gravity
displacement autoclave at 121°C for 30 min; clean; rinse in water;
and subject to routine sterilization.
[CDC NOTE: The pan containing sodium hydroxide should
be covered, and care should be taken to avoid sodium hydroxide spills
in the autoclave. To avoid autoclave exposure to gaseous sodium hydroxide
condensing on the lid of the container, the use of containers with a
rim and lid designed for condensation to collect and drip back into
the pan is recommended. Persons who use this procedure should be cautious
in handling hot sodium hydroxide solution (post-autoclave) and in avoiding
potential exposure to gaseous sodium hydroxide, exercise caution during
all sterilization steps, and allow the autoclave, instruments, and solutions
to cool down before removal.]
- Immerse
in 1N NaOH or sodium hypochlorite (20,000 ppm available chlorine) for
1 hour; transfer instruments to water; heat in a gravity displacement
autoclave at 121°C for 1 hour; clean; and subject to routine sterilization.
[CDC NOTE: Sodium hypochlorite may be corrosive to some instruments.]
- Immerse
in 1N NaOH or sodium hypochlorite (20,000 ppm available chlorine) for
1 hour; remove and rinse in water, and then transfer to open pan and
heat in a gravity displacement (121°C) or porous load (134°C)
autoclave for 1 hour; clean; and subject to routine sterilization.
[CDC NOTE: Sodium hypochlorite may be corrosive to some instruments.]
How should instruments
used in patients with no clear diagnosis at the time of a neurosurgical
procedure be reprocessed?
In some
patients undergoing neurosurgery, a CJD diagnosis that is not suspected
before the procedure may be confirmed after the neurosurgery. For this
group of patients, in whom the clinical diagnosis leading to the neurosurgical
procedure remains unclear, the instruments should be reprocessed in the
same manner as that for instruments used in procedures involving suspected
or confirmed CJD patients. Unless a clear non-CJD diagnosis is established,
these patients should be considered as potentially suspected CJD patients
for all other infection control requirements.
How should heat-sensitive instruments or materials that come in contact
with suspected or confirmed CJD patients be decontaminated?
All disposable
instruments, materials, and wastes that come in contact with high infectivity
tissues (brain, spinal cord, and eyes) and low infectivity tissues (cerebrospinal
fluid, kidneys, liver, lungs, lymph nodes, spleen, and placenta) of suspected
or confirmed TSE patients should be disposed of by incineration. Surfaces
and heat-sensitive re-usable instruments that come in contact with high
infectivity and low infectivity tissues should be decontaminatedby flooding
with or soaking in 2N NaOH or undiluted sodium hypochlorite for 1 hour
and rinsed with water.
[CDC NOTE: Sodium hypochlorite may be corrosive to some
instruments.]
What kinds of precautions should be taken while embalming the bodies of
patients with suspected or confirmed CJD?
An autopsied
or traumatized body of a suspected or confirmed CJD patient can be embalmed,
using the precautions outlined in the WHO CJD
infection control guidelines. CJD patients who have not been autopsied
or whose bodies have not been traumatized can be embalmed using Standard
Precautions. Family members of CJD patients should be advised to avoid
superficial contact (such as touching or kissing the patient's face) with
the body of a CJD patient who has been autopsied. However, if the patient
has not been autopsied, such contact need not be discouraged.
Additional recommendations for CJD infection
control practices not addressed in this Q&A can be obtained from the
"WHO
Infection Control Guidelines for Transmissible Spongiform Encephalopathies:
Report of a WHO Consultation, Geneva, Switzerland, 23-26 March 1999."
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