New Creutzfeldt-Jakob disease tests have high sensitivities, specificities

These findings are encouraging because clinicians and researchers have long sought a sensitive and minimally invasive diagnostic tool specifically targeted to the protein that causes all forms of CJD, said Dr. Colin L. Masters.

It will, however, be important for additional studies to determine more precise estimates of the tests’ specificities – necessitated by the wide confidence intervals reported for the tests’ specificities – because the techniques used can give rise to "breakthrough" false-positive results. "Creutzfeldt-Jakob disease is extremely uncommon, and a test without near-perfect specificity may also result in many false positive results if it is applied to patients with a low probability of having the disease. In these circumstances, it is important to highlight the preliminary nature of these studies," Dr. Masters wrote.

Moreover, the finding that abnormal prion protein "seeds" are found in the olfactory mucosa "at concentrations equivalent to those in diseased brain, and several logs greater than those in cerebrospinal fluid," has implications for infection control. "Some experts have [already] recommended appropriate decontamination of surgical instruments that come into contact with the olfactory epithelium of patients at high risk for Creutzfeldt-Jakob disease," he said.

Dr. Master is with the Florey Institute of Neuroscience and Mental Health at the University of Melbourne. These remarks were taken from his editorial accompanying the two reports on CJD assays (N. Engl. J. Med. 2014 August 6 [doi:10.1056/NEJMe1407419]).