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Table 1 Proposed classification of entry sites for putative surgical transmission of CJD by risk level.

From: Tissue classification for the epidemiological assessment of surgical transmission of sporadic Creutzfeldt-Jakob disease. A proposal on hypothetical risk levels

Risk level Tissues Anatomical structures / routes
High Brain
Spinal cord
Retina, optic nerve
Spinal ganglia
Trigeminal ganglia
Pituitary gland
Dura matera
Lower Peripheral nervesb
Lymph nodesc
Blood vesselse
Olfactory mucosa
Skeletal muscle
Anterior ophthalmic
Subcutaneous (high density of sensitive nerve terminals)f
Lowest Other Other
  1. aDura mater does not contain pathological PrP in CJD patients and its infectivity has not been tested. It is included among high-infectivity tissues in the WHO classification because of evidence of iatrogenic transmission through dura mater grafts.11The same rationale has been applied to its inclusion in the present table.
  2. bOnly surgical procedures on peripheral nerves (e.g., amputation, vagotomy, etc.) will be classified according to this tissue.
  3. cSurgical procedures that include this tissue as putative risk are those involving direct manipulation of lymph node chains, e.g., lymph node excision, oncological lymphadenectomy, and intra-abdominal procedures with extensive section of lymph node chains, such as cholecystectomy, gastrectomy and diverse types of bowel resection.
  4. dAlthough tonsil and thymic tissue have yielded negative results for infectivity and presence of pathological PrP in sporadic CJD tissue (tonsillar tissue has not yet been tested for infectivity), they are included in the table in the lower level group, together with the spleen and lymph nodes for biological reasons, in order to assess the role of peripheral lymphoid tissue in surgical transmission.
  5. eOnly procedures involving direct surgery on blood vessels will be classified according to this tissue.
  6. fHand and facial subcutaneous tissue will be included under this heading.