Diagnosis of Creutzfeldt-Jakob Disease in Canada: An Update on Cerebrospinal Fluid Testing from 2016 to 2024

Abstract

Background: Canada's National Microbiology Laboratory offers diagnostic testing of Creutzfeldt-Jakob disease (CJD) and related prion diseases. Since 2016, the highly sensitive and specific end-point quaking-induced conversion assay (EP-QuIC) of CSF samples has been used for antemortem CJD diagnostic testing alongside tests for surrogate biomarkers 14-3-3 and hTau. To assess EP-QuIC's utility, we undertook a retrospective study of Canadian CJD diagnostic testing conducted between 2016 and 2024.

Methods: Using CJD CSF test results collected between 2016 and 2024, we analyzed the CJD incidence in Canada, estimated based on positive EP-QuIC tests. Multivariate regression models were used to further evaluate CJD CSF testing between CJD subtypes, genders, age groups and codon 129 genotypes.

Results: From 2016 to 2024, the CJD incidence across Canada was estimated at 1.51 cases per million population per year. CJD incidence did not vary significantly across provinces, although a slight increase in CJD incidence was detected in New Brunswick due to increased sampling rates. EP-QuIC offered higher test sensitivity than both surrogate biomarker tests. Analysis of biomarker abundances and test positivity rates across biochemical subtypes revealed significant differences. We also detected variation in CSF test positivity rates across age groups and a trend of increasing biomarker abundance with age within EP-QuIC-negative cases. No significant variation was detected between males and females.

Conclusion: EP-QuIC exhibits exceptional specificity and sensitivity for antemortem diagnosis of CJD, providing a valuable tool for the diagnosis of human prion diseases and for improved surveillance.

Keywords: CJD diagnostics; CJD surveillance; Creutzfeldt-Jakob disease; QuIC; prion.