Review: Risk of Endoscope-Related CJD/vCJD Cases is Very Low

Published on:

September 8, 2021

Last updated on:

December 13, 2023

• Scientific Summary

• In a review, experts examined guidelines for the reprocessing of flexible endoscopes used on patients with suspected or confirmed prion disease ^[1].

• So far, there have been no described cases of prion transmission by flexible endoscope.

• Even automated partial reprocessing (cleaning only) of endoscopes substantially reduces protein residues.

Creutzfeldt–Jakob disease (CJD) and variant Creutzfeldt-Jakob disease (vCJD) are very rare fatal conditions that affect the brain. CJD and vCJD are caused by prions, which are special proteins that occur in the brain tissue. Usually, prions are present in a non-pathogenic form. If the proteins fold incorrectly, they can cause spongiform encephalopathy.

The types of CJD that occur in humans are sporadic, inherited, and transmitted. This includes the very rare iatrogenic type of transmission, in which prions are transmitted during medical procedures. vCJD is a zoonotic form of prion disease (bovine spongiform encephalopathy [BSE] prions from cattle). The epidemiological peak of vCJD among humans was reached in 2000. To minimize the potential risk of transmitting prions through the use of flexible endoscopes, global guidelines were developed for handling and reprocessing these devices.

Comparison of national and international guidelines

A review performed in 2020 systematically examined the different national guidelines ^[1]. For suspected or confirmed cases of CJD and vCJD, several of the guidelines recommend using specific procedures, quarantine procedures, and additional reprocessing procedures for endoscopes. Overall, however, the guidelines differ in many details, as the authors show by means of several examples. In Switzerland, Great Britain, and Canada, for example, the additional procedure of running the endoscope washer-disinfector (EWD/AER) on an unloaded self-disinfection cycle is recommended. In contrast, Germany, Austria, the Netherlands, France, the USA, and Australia, provide no explicit recommendations regarding this procedure.

No transmission of prions by flexible endoscopes

A study conducted in 2007 initially deemed it possible for vCJD to be transmitted by flexible endoscope. To date, however, there have been no known cases of prion transmission by flexible endoscope.

The review also shows that automated cleaning of endoscopes alone leads to a substantial reduction of protein residues. After cleaning, the largest detected quantity of protein present on the endoscopes was at least 100,000 times lower than the prion concentration required to trigger vCJD in animals via oral uptake. After complete reprocessing with additional rinsing steps, the protein content can be even lower. The authors therefore conclude that risk of new endoscope-related vCJD cases is low and will also remain minimal in the future.

Procedure after validated reprocessing

If a prion contact has occurred after several usages and validated reprocessing of the flexible endoscope, the authors claim that the endoscope does not need to be quarantined, provided certain parameters are adhered to ^[1]. The following parameters should be complied with accordingly: cleaning immediately after the end of the examination (“bedside cleaning” or “precleaning”), use of a validated reprocessing protocol, use of at least mildly alkaline cleaning agents and no use of fixing agents, and use of single-use brushes and fresh cleaning solutions every time for each endoscope.