The blood tests accurately diagnosed 32 patients between the two studies, distinguishing those with the disease from 391 healthy controls. In both cases, the tests were 100 percent sensitive and 100 percent specific and, in one of the studies, the test managed to identify vCJD prion particles in a blood donation more than a year before the onset of symptoms—a first for prion disease detection.

WIKIMEDIA, US NAVY Thousands of Europeans may be asymptomatic carriers of variant Creutzfeldt-Jakob disease (vCJD), a fatal prion disease that is the human variant of Mad Cow disease. But now, two studies published December 21 in Science Translational Medicine describe new methods for detecting even latent vCJD, which could make blood transfusions safer and help early detection and treatment of the disease.

Luis Concha-Marambio of the University of Texas Houston Medical School and colleagues developed one blood test and tested it on 14 individuals with vCJD and 153 controls. Daisy Bougard of the University of Montpellier in France and colleagues tested a similar technique on 18 individuals with vCJD and 238 without. Although the tests are slightly different, both involve amplifying prions in a blood sample by culturing them with normal proteins, subjecting them to sound waves, and then adding more proteins in successive waves. The process mimics the ideal environment for a prion to replicate and, if the sample is infected, the healthy proteins begin to form clumps and infect other proteins until there are so many abnormal proteins that the disease is relatively easy to detect. If the sample is not infected, the proteins remain normal.

Claudio Soto, a neurologist at the University of Texas Health Houston Medical School, a coauthor on one of the studies, told Scientific American that he founded a startup to develop the technology and test its accuracy in larger samples. He said he expects the test to be commercially available within two years, and added that technique may also help screen for more common diseases such as Alzheimer’s and Parkinson’s which, like vCJD, appear to involve abnormally-folded proteins.

“This is a big problem with all these brain diseases, that when the disease manifests clinically, it’s always very late, and at the time that the brain is largely destroyed,” Soto told Scientific American. “We are trying to develop a blood test to detect Alzheimer’s disease and Parkinson’s disease before the clinical symptoms of the disease appear so we have better possibilities for therapies to work.”