Blood test for screening mad cow disease to come soon: Study

By Dr. Ananya Mandal, MDFeb 6 2011

UK scientists have developed a new blood test that can diagnose cases of variant Creutzfeldt-Jakob Disease (vCJD), a rare, fatal brain disease caused by proteins known as prions. These prions are also responsible for the mad cow disease, or bovine spongiform encephalopathy (BSE). This test could in near future be used to identify contaminated blood and prevent transmission of the disease during blood transfusions, the researchers said.

It is estimated that 1 in 4,000 people could harbor the disease in the U.K., the researchers said. Since symptoms of the condition take years to appear, the people with the disease could spread it via blood transfusions and surgeries that use contaminated blood.

Mad cow disease, which humans can get by eating beef from infected cattle, has killed 171 people and been responsible for the deaths of more than 4 million cattle, slaughtered in attempts to eradicate the disease.

The team ran the test on 190 samples, and it was able to pick out 15 of the 21 samples from people with the disease. That is a 71.4% success rate. On top of that, the test did not turn up any false positives – in other words, it did not incorrectly indicate that the abnormal prion was in any of the healthy samples.

Study researcher John Collinge, of The UK Medical Research Council Prion Unit added that the test might also help scientists to better gauge how many people have vCJD. However, the researchers cautioned that before the test is implemented, it must be further studied in large numbers of people. And scientists need to determine how many among those with positive blood tests actually go on to develop vCJD.

Luisa Gregori, of the U.S. Food and Drug Administration writing in a commentary accompanying the study said it was not clear whether the test could detect vCJD in people who do not yet show symptoms of the disease. These patients would presumably have lower levels of infectious prions in their blood, Gregori said. The study and the commentary is published online in the journal the Lancet.

The Department of Health is monitoring the research closely while NHS Blood and Transplant said it “may be a first step towards development of a screening test which could be of value in establishing the prevalence of infection, as a blood donor screening test or for testing people considered at risk for public health purposes.”