Introduction to Prions (4)

Question 1

What are the HIGH risk categories of tissue by vCJD?

Answer 1

Brain, spinal cord, spinal ganglia, dura mater, cranial nerves, cranial ganglia, posterior eye.

Question 2

What are the high MEDIUM categories of tissue by vCJD?

Answer 2

Anterior eye and cornea, olfactory epithelium, tonsil, appendix, spleen, thymus, other lymphoid tissue.

Question 3

What are the high LOW categories of tissue by vCJD?

Answer 3

Peripheral nerve, dental pulp, gingival tissue, blood and bone marrow, CSF, placenta, urine, other tissue e.g. saliva.

Question 4

Is saliva contaminated with blood high, medium or low risk for vCJD?

Answer 4

Assume that all dental instruments will be contaminated by saliva. Many dental procedures result in saliva being contaminated with blood.

This degree of contamination is assumed to be of low risk for vCJD.

Question 5

In the dental field, what are the major problems with CJD?

Answer 5

• Conventional disinfection and sterilisation protocols ineffective.
  Prions adhere to steel - all cleaning protocols should be optimised to remove protein.
• Heat resistant

Question 6

How do you sterilise prion protein from instruments?

Answer 6

cleaning

• Importance of cleaning to eliminate visual evidence of contamination.
• Instruments used for high or medium risk procedures on patients at increased risk of CJD should be reused exclusively on that patient or quarantined.

Question 7

What tissues in relation to dentistry could be infected by CJD?

Answer 7

dental pulp,
gingival tissue,
blood,
saliva

Question 8

What is the chance of these tissues being liberated during dental treatment?

Answer 8

depends on procedure

e.g. root canal, there will be expose to the dental pulp, blood and saliva exposure

Question 9

What is the amount and infectivity of material remaining after decontamination?

Answer 9

want less that 1 in a million chance of infected prion proteins remaining after sterilisation

Question 10

What are the chances of tissue transfer?

Answer 10

To date, no cases of dental treatment being a factor in Iatrogenic CJD

All theoretical at the moment.

Question 11

Do you need to ask a patient about CJD during a medical history?

Answer 11

Yes

Conclusion: the risk of vCJD transmission during dental treatment is low but theoretically possible.

Carry out risk assessment.

Is that patient at higher risk of having CJD that others.

Question 12

What instrument single use?

Answer 12

endodontic file

difficult to clean, even going through an autoclave.

they should be discarded after use.

Question 13

Which of the following statements describes prions?

A) The replication of prions is sporadic.

B) The major site of prion protein replication is in the lymphoid tissue.

C) Infection control practices differ between the UK and USA.

D) Immunisation against prion induced diseases is now available.

Answer 13

C

Question 14

Which of the following dental procedures are implicated in the transmission of vCJD?

A) Endodontics
B) Extractions
C) Periodontal surgery.
D) None of the above.

Answer 14

D

Question 15

A 30-year-old British man is diagnosed with neurological symptoms compatible with vCJD.

State whether each statement is true or false.

A) The infectious agent is a low molecular weight protein devoid of nucleic acids.
B) Standard infection control procedures suffice for dental treatment in UK.
C) The disease will resolve spontaneously.
D) The patient should be treated at the end of the day.

Answer 15

A) TRUE
B) TRUE
C) FALSE
D) FALSE