Is CJD a real threat to public health or is it more a theoretical problem? If it is a problem what do we do with single use items used during minimally invasive surgery and resterilised with ethylene oxide? They can come into contact with high or medium infectivity tissue. Should we discard everything always or just in case of an increased risk patient?

I think that you should always discard every single use item after each operation. Otherwise you will become a "manufacturer" and not just a reprocessor and will be totaly responsable for the product you produce. You must validate the sterilization and the safe reuse off such a single use item.

Is the effect of steam sterilization off prion contaminated instruments, after proper cleaning and disinfecting, ever been tested? I hope that someone will be able to tell us if the normal prion bioburden on instruments can be eliminated by a standard steam sterilization cycle. If the standard cycle is sufficient then CJD should not be a big problem in the CSSD. If it's not we could be in trubble with many off the surgical instruments and trays used.

Vis, R.

According Jack Van Asten (Sterilization of prions, Zentral Sterilisation 1995, 3: 385-394 and Prions and hospital infections, The Lancet 1996, vol 347: 967) sterilization of prion-contaminated medical devices need not to be a problem with a standard 3-5 min 134° sterilization cycle, provided that the use of aldehydes is avoided and a properly functioning moist-heat sterilizer with adequate active air removal is used. He bases this on two observations:

1. That there are no data available which indicate that a reliable high-temperature (134°) moist-heat sterilization process is not adequate for prion inactivation in a normal hospital routine.
2. That the inactivation of prions can be considered as a first-order reaction, in which case the generally accepted inactivation kinetics apply.

The RIVM (National Institute Of Public Health And The Environment, The Netherlands) advises the application of a special sterilization process only in case of a strong suspicion of a positive CJD diagnosis.

Wim Renders

I would like to give an additional comment to question no. Q000-002 concerning the risk of acquirung CJD: is it a real threat or just a more theoretical problem.

Collins and coworkers performed a case-control study by comparing the medical history and selected demographic characteristics of 241 definite CJD patients, ascertained from the Australian National CJD Registry. 784 control were taken at random from the community by telephone interview. They found out that surgical procedures were significantly associated with sporadic CJD. There was also a significant association to residence or employment on a farm or market garden for more than 10 years. No significant risk was demonstrated for blood transfusion, organ transplantation, dental procedures or occupation. The authors suggest that surgical treatment my account for a proportion of cases of sporadic CJD.

Although these findings need to be replicated by independent studies, they may lead to a new assessment of the question whether or not CJD poses a "real" threat to surgical patients. (Collins S, Law MG, Fletcher A, Boyd A, Kaldor J, Masters CL: Surgical treatment and risk of sporadic Creutzfeldt-Jacob disease: a case-control study. Lancet 1999; 353: 693-697).

Prof. Dr. P. Heeg
Dept. of Hospital Infection Control
University of Tübingen, Germany

Isolation of Patients With CJD or vCJD

Standard Precautions are recommended when caring for patients with Creutzfeldt-Jakob disease (CJD), new-variant CJD (vCJD), or other unexplained rapidly progressive dementias (see Guidelines: Centers for Disease Control and Prevention/Healthcare Infection Control Practices Advisory Committee [CDC/HICPAC] Guidelines for Isolation Precautions in Hospitals). In addition, the CDC/HICPAC guidelines recommend that special precautions are necessary for handling and decontamination of blood, body fluids, and tissues from patients with confirmed or suspected disease according to recommendations from the College of American Pathologists (CAP). Those recommendations are included in the following section, Handling Tissue From Patients With Possible CJD. Private rooms for patients with CJD or vCJD are not necessary because the CJD agent is generally not transmitted from person to person.

Patients with known or suspected CJD should not donate blood, organs, or human tissue for preparation of biologic products to be used in humans (eg, dura mater, pituitary hormones, and human interferon).

Sterilization and Cleaning of Equipment

The data outlining appropriate measures for decontamination of equipment following potential exposure to the CJD agent are somewhat limited, and best practices have yet to be agreed on. However, current recommendations from several agencies/organizations are presented below.

According to the Association for Professionals in Infection Control and Epidemiology (APIC) Guideline for Selection and Use of Disinfectants (see Guidelines), items potentially contaminated with the CJD agent require unique decontamination procedures. The APIC recommendations include the following:

• Contaminated material should undergo steam sterilization for at least 1 hour at 132°C.
• When autoclaving of critical and semicritical items is not possible, immersion in 1N NaOH for 1 hour at room temperature is an alternative procedure.
• Noncritical patient care items or surfaces (eg, autopsy tables, floors) may be disinfected with either bleach (undiluted or up to 1:10 dilution) or 1N NaOH at room temperature for 15 minutes or less.
• Single-use items and instruments that are impossible to clean should be discarded.

Similar recommendations are available from the Centers for Disease Control and Prevention's Hospital Infections Program (CDC/HIP) (see Guidelines):

• Steam autoclave for 1 hour at 132°C.
• Immerse in 1N NaOH for 1 hour at room temperature.
• Immerse in 0.5% NaOH for 2 hours at room temperature.

The HIP website indicates that the recommendations are under revision at this time. The revised recommendations will be included here when they are available.

The World Health Organization (WHO) Report of a WHO Consultation on Medicinal and Other Products in Relation to Human and Animal Transmissible Spongiform Encephalopathies states the following with regard to preventing transmission of the CJD agent from contaminated instruments (see Guidelines):

• It is strongly recommended that instruments used for neurosurgical and invasive ophthalmologic procedures on patients with CJD be discarded.
• If instruments are to be reused, they should be immersed in 1N NaOH for 1 hour, cleaned, and then autoclaved at 134°C for 1 hour.

Pete Bobb