Surgery on asymptomatic patients

Currently it is guesswork that the disease can be transferred from one patient to another via surgical instruments at all. What has been done is to produce statistical risk rates using animal models. When this is done it can be seen that the risk would be low unless there was a reasonably high amount of infection in the tissues that were being cut.

Variant CJD has the problem that we feel peripheral tissues are infected relatively early and will be at a relatively high infectivity compared with other TSEs. Because of this several things have happened:

Risk Assessment for Transmission of a vCJD via Surgical Instruments: a modelling approach. This shows that there is a risk but that it is small. Much of the model, unfortunately is poor because we simply cannot know how much infectivity is taken from the instruments in their cleaning process.

The size of the experiments needed would need to be too great. Going through this site it is possible to find the mathematical model that is used to demonstrate and calculate the risks. This was demanded by SEAC at the time. This was eventually published using optimistic levels of infectivity in the tissues

Surgery on asymptomatic patients. The problem is that we dont know which people represent the risk. As a result, in early 2001, the DoH demanded that all tonsillectomies should be done only with disposable surgical instruments and that these should be incinerated after use.

In December 2001 this was withdrawn when a child died because of the poor use of such instruments. The actual science behind this withdrawal must have followed a risk analysis but this has not been published.

Variant Creutzfeldt-Jakob disease (vCJD) minimising the risk of transmission HSC 1999/178. This goes in to specific directions as to how to handle specific instruments and how some should be discarded after use (e.g. lumbar puncture instruments) and others should currently be not. In this is makes it clear that it is clinically up to the staff to decide whether a risk is present of the patient being infected for CJD.

The document is actually quite clear about very specific things and individual ideas are difficult to get around. One factor is clear from this, however, and that is that they cannot get around the fact that many people may be infected and there is no way to tell which ones these are. This is a major document and should be looked at by all people in infection control.

The problem underneath all this is that infectivity is likely to be in tissues long before any signs or symptoms of disease appear to warn the doctors. As a result of this the risk from surgical instruments may be there following surgery into patients that would seem to be uninfected.