WHO infection control guidelines for transmissible spongiform encephalopathies (consultation 23-26 March 1999, WHO/CDS/CSR/APH/2000.3)

Key facts

• Title and number: WHO Infection Control Guidelines for Transmissible Spongiform Encephalopathies, report of a WHO Consultation, document WHO/CDS/CSR/APH/2000.3, from the WHO unit for emerging and other communicable diseases (surveillance and control).
• The cover gives the consultation as 23-26 March 1999 in Geneva, while the introduction says 24 to 26 March; the one-day difference is unresolved.
• The meeting was chaired by Dr Paul Brown, with Dr Martin Zeidler and Dr Maurizio Pocchiari as rapporteurs.
• Status: the document says it is not a formal publication of WHO and may be freely reviewed, reproduced and translated, but not sold; the copy read says it was downloaded from the WHO/EMC web site with original covers and participant lists removed.
• Scope: guidance for preventing events described as extremely rare (transmission through a surgical procedure) or hypothetical (transmission to a healthcare worker or family member); where the experts could not agree, the text says so.
• Core principle on care: normal social and clinical contact and non-invasive investigations carry no risk, no patient should be refused admission to a healthcare setting, and isolation is unnecessary because Standard Precautions suffice.
• Risk is framed on three factors: the probability a person has TSE, the infectivity of the tissue involved, and the route of exposure.
• Tissue categories (Table 2): high infectivity for brain, spinal cord and eye; low infectivity for CSF, kidney, liver, lung, lymph nodes/spleen and placenta; no detectable infectivity for tissues and excretions including blood, urine, saliva and muscle. The text notes the grouping rests on how often infectivity was detected, not on quantitative data.
• Reported iatrogenic exposure routes listed as the basis for "at risk" persons were dura mater grafts (110 cases), cadaveric pituitary hormones (130), corneal transplants (3) and neurosurgery (6) at the time of writing.
• Surgery: advance notice to the infection control team, planned instrument handling, single-use items where possible, and incineration of high infectivity waste; instruments touched by CSF are treated like those touching high infectivity tissue.
• Annex III ranks decontamination options from most to least severe, with incineration first and preferred, then combinations of heat and chemical treatment; the safest route for instruments is stated to be discarding and destroying them. A table lists common disinfectants as ineffective or only partly effective. Detailed parameters are in the source and are not reproduced here.
• Laboratory section: recommendations are for healthcare laboratories, not research laboratories; CSF analysis should not use automated equipment; routine blood tests need no special measures.
• After death: normal measures for body removal, autopsy is encouraged to confirm diagnosis with protective precautions, family contact with the body need not be discouraged, and anatomy departments should not accept bodies of confirmed, suspected or at-risk persons unless equipped for it.
• Variant CJD was addressed in an annex without extensive discussion because few data existed; sporadic CJD precautions were suggested to apply, with a more conservative approach for surgery and laboratory work.
• The consultants asked for an international effort to identify stored tissues from people who later developed CJD, to clarify infectivity in the pre-clinical phase.
• A CDC Q and A, reviewed May 2003 and archived in November 2004, pointed health workers to the guidelines, drawing on Annex III and Table 2.
• A publisher listing shows a print edition (ISBN 9789241599009, December 2001, about 36 pages); seen only as a search result.

Timeline

1. 1999to 1999-03-26 WHO consultation in Geneva (the introduction gives 24 to 26 March) chaired by Paul Brown.
2. 2000Report issued as WHO/CDS/CSR/APH/2000.3 (year from the document number and the scout record; the mirror shows no date).
3. 2003CDC infection control Q and A, citing the guidelines, last reviewed.
4. 2004Archive snapshot of the CDC page.