Referencing this article, in which health officials express concern about possibly having exposed neurosurgery patients to CJD. They operated on a patient who was later found to have had CJD, and then used the same surgical instruments on other patients.
The claim in the article is that normal sterilization procedures (autoclave?) are not enough to wipe out the prions that cause CJD.
So what exactly does it take to wipe out CJD prions? And if normal sterilization procedures are not enough to assure safety from CJD, then why would hospitals continue to use those procedures for instruments employed in neurosurgery?
I know we have some molecular biologists here but until they check in, prions are misfolded versions of normal proteins that are able to corrupt the properly folded versions. For anyone that doesn’t understand what it means for a protein to be properly folded, it means for it to adopt the 3 dimensional structure that allows it to perform its designed function.
Not all proteins have a rigid 3D structure but that’s another matter. The point is that where prions are concerned, the misfolded versions not only have the ability to cause the functional versions of the protein to become misfolded and therefore “infect” other versions of the same protein but also tend to be highly stable andresistant to being denatured via normal means.
After a little reading I come to the reluctant conclusion that there is no satisfactory way of completely sterilising instruments that may be contaminated. Certainly not in any cost effective system anyway.
Probably, the only solution is to dispose of them.
There is another point here - the element of risk: If, in the unlikely event that a neurosurgeon wants to stick instruments into your brain, the chances of them being infected are very small. You are far more likely to suffer injury or death on your way to the hospital.
Prions are just proteins, so they can be denatured by heat or hydrolyzed into their component amino acids by reasonably strong acids or other caustic reagents, or proteolytic enzymes. Unfortunately, normal sterilization does not use such reagents, and the heat required for denaturation is probably a good deal more than that used in normal sterilization (which is sufficient to kill actual infective organisms).
I don’t think there is any doubt that surgical instruments could be sterilized so as to remove prions. The problem is that established sterilization procedures are not enough, and introducing measures strong enough to render prions universally would be a very expensive to what is, in reality, a very rare danger.
I imagine (I certainly hope) that now this case has been publicized, hospitals will at least institute procedures to give special treatment to instruments used in cases where there is a reasonable suspicion of CJD (or any other prion based disease).
Ever since I first learned about prions, I’ve felt that Vonnegut anticipated this type of thing with his “Ice-9”. (ETA: and now after quickly scanning that Wiki link, it seems I’m not alone. Cool.)
That is certainly true, but sporadic CJD still does occur. And the statistics are increasingly favourable for the number of future probable cases in the UK based on known cases and genetic subtyping. There is still no good diagnostic test for CJD, so risk reduction is the best approach.