2010-10-29-世界卫生组织-WHO_Tables_on_Tissue_Infectivity_Distribution_in_Transmissible_Spongiform_Encephalopathies_21页_172kb

WHO Tables on Tissue Infectivity Distribution in Transmissible Spongiform Encephalopathies (TSEs)

Introduction

The "WHO Tables on Tissue Infectivity Distribution in Transmissible Spongiform Encephalopathies" were originally compiled by an expert group during a WHO consultation in 2003 and updated in 2005. These tables reflect the current understanding of infectivity in various tissues, secretions, and excretions of individuals with sporadic or variant Creutzfeldt-Jakob disease (CJD), cattle with BSE, sheep with scrapie, and newly included elk and deer with Chronic Wasting Disease (CWD). The tables do not aim to revise the 2006 WHO Guidelines but provide updated information relevant to the potential transmission of variant CJD through blood and medicinal products made from bovine-derived materials.

The tables categorize tissues into three groups: high-infectivity (IA), lower-infectivity (IB), and tissues with no detectable infectivity (IC). The categorization is based on naturally occurring disease or primary oral infection in ruminants. Experimental models using adapted TSE strains are not included due to potential variability in results. For tissues of public health interest, experimental results are noted in footnotes.

Major Categories of Infectivity

Table IA: High-infectivity tissues

These tissues have a high titer of infectivity in the later stages of all TSEs and are anatomically associated with the central nervous system (CNS). Examples include:

• Brain: +
• Spinal cord: +
• Retina: NT (in humans), + (in cattle, sheep, and deer)
• Optic nerve: NT (in humans), + (in cattle, sheep, and deer)
• Spinal ganglia: +
• Trigeminal ganglia: +
• Pituitary gland: NT (in humans), + (in cattle, sheep, and deer)
• Dura mater: NT (in humans), + (in cattle, sheep, and deer)

Table IB: Lower-infectivity tissues

These tissues have been found to contain infectivity or PrP^TSE in at least one form of TSE. Examples include:

• Peripheral nervous system:
  • Peripheral nerves: +
  • Autonomic ganglia: NT (in humans), + (in cattle, sheep, and deer)
• Lymphoreticular tissues:
  • Spleen: +
  • Lymph nodes: +
  • Tonsil: +
  • Nictitating membrane: NA (in humans), + (in cattle, sheep, and deer)
  • Thymus: NT (in humans), + (in cattle, sheep, and deer)
• Alimentary tract:
  • Esophagus: NT (in humans), + (in cattle, sheep, and deer)
  • Fore-stomach (ruminants only): NA (in humans), NT (in cattle, sheep, and deer)
  • Stomach/abomasum: NT (in humans), + (in cattle, sheep, and deer)
  • Duodenum: NT (in humans), + (in cattle, sheep, and deer)
  • Jejunum: NT (in humans), + (in cattle, sheep, and deer)
  • Ileum: NT (in humans), + (in cattle, sheep, and deer)
  • Appendix: (-) (in humans), + (in cattle, sheep, and deer)
  • Colon/caecum: NT (in humans), + (in cattle, sheep, and deer)
  • Rectum: [+] (in humans), + (in cattle, sheep, and deer)
• Reproductive tissues:
  • Placenta: NT (in humans), + (in cattle, sheep, and deer)
  • Ovary: NT (in humans), - (+) (in cattle, sheep, and deer)
  • Uterus: NT (in humans), - (+) (in cattle, sheep, and deer)
• Other tissues:
  • Mammary gland/udder: NT (in humans), + (in cattle, sheep, and deer)
  • Skin: NT (in humans), + (in cattle, sheep, and deer)
  • Adipose tissue: NT (in humans), + (in cattle, sheep, and deer)
  • Heart/pericardium: NT (in humans), + (in deer and elk)
• Body fluids, secretions and excretions:
  • CSF: - (in humans), + (in cattle, sheep, and deer)
  • Blood: + (in humans), ? (in cattle, sheep, and deer)
  • Saliva: NT (in humans), - (in cattle, sheep, and deer)
  • Milk: NT (in humans), + (in cattle, sheep, and deer)
  • Urine: NT (in humans), + (in cattle, sheep, and deer)
  • Feces: NT (in humans), + (in cattle, sheep, and deer)

Table IC: Tissues with no detected infectivity or PrP^TSE

These tissues have not shown detectable infectivity or PrP^TSE in any form of TSE. Examples include:

• Reproductive tissues:
  • Testis: NT (in humans), - (in cattle, sheep, and deer)
  • Prostate/Epididymis/Seminal vesicle: NT (in humans), - (in cattle, sheep, and deer)
  • Semen: NT (in humans), - (in cattle, sheep, and deer)
  • Placenta fluids: NT (in humans), NT (in cattle, sheep, and deer)
  • Fetus: NT (in humans), NT (in cattle, sheep, and deer)
  • Embryos: NT (in humans), ? (in cattle, sheep, and deer)
• Musculo-skeletal tissues:
  • Bone: NT (in humans), NT (in cattle, sheep, and deer)
  • Tendon: NT (in humans), NT (in cattle, sheep, and deer)
• Other tissues:
  • Gingival tissue: NT (in humans), NT (in cattle, sheep, and deer)
  • Dental pulp: NT (in humans), NT (in cattle, sheep, and deer)
  • Trachea: NT (in humans), NT (in cattle, sheep, and deer)
  • Thyroid gland: NT (in humans), - (in cattle, sheep, and deer)
• Body fluids, secretions and excretions:
  • Colostrum: NT (in humans), (?) (in cattle, sheep, and deer)
  • Cord blood: NT (in humans), (?) (in cattle, sheep, and deer)
  • Sweat: NT (in humans), NT (in cattle, sheep, and deer)
  • Tears: NT (in humans), NT (in cattle, sheep, and deer)
  • Nasal mucus: NT (in humans), NT (in cattle, sheep, and deer)
  • Bile: NT (in humans), NT (in cattle, sheep, and deer)

Key Notes and Considerations

• The presence of PrP^TSE does not necessarily equate to infectivity, especially in tissues tested using highly sensitive methods like PMCA or Tg mice.
• Infectivity in some tissues, such as skin and kidney, was only detected in experimental models, not in natural conditions.
• The inclusion of CWD data is important due to its spread and potential for transmission.
• Infectivity categories are not equivalent to risk categories; the route of exposure and amount of tissue involved also affect risk.
• The data are incomplete and may change with further research, especially as more sensitive tests become available.