An anonymous reader writes from a report via Scientific American: Eating beef from an animal infected with mad cow disease can lead to an untreatable condition that attacks the brain and is universally fatal, but symptoms can take decades to emerge. Thankfully, Claudio Soto, a neurologist at McGovern Medical School at UTHealth in Houston, and her team, as well as a team led by Daisy Bougard of the French Blood Establishment in Montpellier, France, have developed new blood-screening technology that can spot Mad Cow Disease (known as variant Creutzfeldt-Jakob disease) with 100 percent accuracy -- perhaps years before it attacks. From the Scientific American: "Misfolded proteins called prions cause both mad cow and variant Creutzfeldt-Jakob disease. Once they invade the brain, they begin recruiting normal proteins and forcing them to adopt the same abnormal shape. The prions and the blighted proteins clump together forming increasingly large aggregate deposits that wreak havoc on the brain and invariably lead to death. The disease, however, has a long incubation period. In the interim, the prions hang out in non-brain tissues such as the appendix and tonsils, and because they do not cause symptoms, the infected person becomes a silent carrier. [The two teams] ran the test on blood samples from variant Creutzfeldt-Jakob disease patients in the U.K. and France. The two teams used slightly different methods, but the basic idea was the same: the test essentially mimics the progression of the disease in an accelerated, artificial environment. First the prion proteins are separated from the blood and combined with normal proteins, which take on an abnormal shape, forming aggregate clumps. Then, the aggregates are pulled apart and recombined with more normal proteins. The process is repeated over and over again, in effect replicating the prion proteins until very small quantities are amplified enough to be easily detected. If there are no prions present in the blood, nothing happens. Between the two studies, the test was able to identify a total of 32 cases of variant Creutzfeldt-Jakob disease with 100% percent accuracy, and there were no false positives among the 391 controls, which included regular blood donors, patients with a different form of Creutzfeldt-Jakob disease, and patients with other neurological diseases. In addition, Bougard's group was able to diagnose variant Creutzfeldt-Jakob disease in the blood of two patients 1.3 and 2.6 years before they developed clinical symptoms." The two studies -- "Detection of prions in blood from patients with variant Creutzfeldt-Jakob disease" and "Detection of prions in the plasma of presymptomatic and symptomatic patients with variant Creutzfeldt-Jakob disease" -- were published in the journal Science Translational Medicine.

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