title: Bioassay studies support the potential for iatrogenic transmission of variant Creutzfeldt Jakob Disease through dental procedures.
abstract: BACKGROUND
  Evidence is required to quantify the potential risks of transmission of variant Creutzfeldt Jakob (vCJD) through dental procedures. Studies, using animal models relevant to vCJD, were performed to address two questions. Firstly, whether oral tissues could become infectious following dietary exposure to BSE? Secondly, would a vCJD-contaminated dental instrument be able to transmit disease to another patient?
  
  
  METHODS
  BSE-301V was used as a clinically relevant model for vCJD. VM-mice were challenged by injection of infected brain homogenate into the small intestine (Q1) or by five minute contact between a deliberately-contaminated dental file and the gingival margin (Q2). Ten tissues were collected from groups of challenged mice at three or four weekly intervals, respectively. Each tissue was pooled, homogenised and bioassayed in indicator mice.
  
  
  RESULTS
  Challenge via the small intestine gave a transmission rate of 100% (mean incubation 157±17 days). Infectivity was found in both dental pulp and the gingival margin within 3 weeks of challenge and was observed in all tissues tested within the oral cavity before the appearance of clinical symptoms. Following exposure to deliberately contaminated dental files, 97% of mice developed clinical disease (mean incubation 234±33 days).
  
  
  CONCLUSIONS
  Infectivity was higher than expected, in a wider range of oral tissues, than was allowed for in previous risk assessments. Disease was transmitted following transient exposure of the gingiva to a contaminated dental file. These observations provide evidence that dental procedures could be a route of cross-infection for vCJD and support the enforcement of single-use for certain dental instruments.
authors.affiliation: Health Protection Agency - Porton Down, Salisbury, Wiltshire, United Kingdom.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Kirby
authors.forename: Joanne
authors.initials: J
authors.lastname: Dickinson
authors.forename: Matthew
authors.initials: M
authors.lastname: Vassey
authors.forename: Mike
authors.initials: M
authors.lastname: Dennis
authors.forename: Mark
authors.initials: M
authors.lastname: Cornwall
authors.forename: Neil
authors.initials: N
authors.lastname: McLeod
authors.forename: Andrew
authors.initials: A
authors.lastname: Smith
authors.forename: Philip D
authors.initials: PD
authors.lastname: Marsh
authors.forename: James T
authors.initials: JT
authors.lastname: Walker
authors.forename: J Mark
authors.initials: JM
authors.lastname: Sutton
authors.forename: Neil D H
authors.initials: ND
authors.lastname: Raven
mesh_terms: D000818:Animals; D001681:Biological Assay; D001921:Brain / Q000821:virology; D002417:Cattle; D007562:Creutzfeldt-Jakob Syndrome / Q000635:transmission* / Q000821:virology; D003729:Dental Care; D003762:Dental Instruments / Q000821:virology*; D004195:Disease Models, Animal; D016643:Encephalopathy, Bovine Spongiform / Q000635:transmission* / Q000821:virology; D005881:Gingiva / Q000821:virology; D006801:Humans; D007049:Iatrogenic Disease; D007421:Intestine, Small / Q000821:virology; D051379:Mice; D018620:PrPSc Proteins / Q000302:isolation & purification* / Q000472:pathogenicity; D012306:Risk
chemical_list: D018620:PrPSc Proteins