Credit: Elise Amendola
Two groups of scientists have developed new tests to diagnose Creutzfeldt-Jakob disease (CJD).
One test uses samples collected from nasal passages to detect sporadic CJD, and the other uses urine samples to identify variant CJD.
The researchers said these tests provide simple methods for differentiating CJD from other diseases and could help prevent the transmission of CJD via blood
transfusions, transplants, or contaminated surgical instruments.
Both tests are described in The New England Journal of Medicine.
Nasal test for sporadic CJD
In one NEJM article, Byron Caughey, PhD, of the National Institute of Allergy and Infectious Diseases in Rockville, Maryland, and his colleagues detailed their results with the nasal test.
The researchers collected 31 nasal samples from patients with sporadic CJD and 43 samples from patients who had other neurologic diseases or no neurologic disease. The team brushed the inside of a subject’s nose to collect olfactory neurons connected to the brain.
Testing these samples allowed the researchers to correctly identify 30 of the 31 sporadic CJD patients (97% sensitivity). The tests also correctly showed negative results for all 43 of the non-CJD patients (100% specificity).
By comparison, tests using cerebral spinal fluid, which is currently used to detect sporadic CJD, were 77% sensitive and 100% specific. And these results took twice as long to obtain.
While continuing to validate the new testing method in CJD patients, the scientists are looking to expand their research to diagnose forms of prion diseases in sheep, cattle, and wildlife. The team also hopes to replace the nasal brush with an even simpler swabbing approach.
Urine test for variant CJD
In another NEJM article, Fabio Moda, PhD, of the University of Texas Medical School at Houston, and his colleagues described results observed with their urine test.
The team noted that the infectious agent in transmissible spongiform encephalopathies appears to be composed exclusively of the misfolded form of the prion protein, PrPSc. So they set out to determine if they could detect PrPSc in the urine of patients with CJD.
The researchers analyzed urine samples from healthy individuals (n=52) and patients with variant CJD (n=68), sporadic CJD (n=14), genetic forms of prion disease (n=4), other neurodegenerative disorders (n=50), and nondegenerative neurologic disorders (n=50).
The group found they could only detect PrPSc in samples from patients with variant CJD. They found “minute quantities” of PrPSc in 13 of the 14 urine samples from variant CJD patients, but PrPSc was not present in any of the samples from the other patients or the healthy individuals.
This suggests the test has a sensitivity of 92.9% and a specificity of 100%.
