A blood test for the human form of mad cow disease is being used in the UK for the first time, it has been revealed.
In a significant step forward in the fight against variant CJD, neurologists have recently been told that the test is available for use.
Professor John Collinge, director of the Medical Research Council's Prion Unit and part of the team that developed the test, said it was "extremely good news".
Speaking to Channel 4 News, he said: "We have recently offered this test to UK neurologists and colleagues around the world (who) are sending us samples from patients in which variant CJD is a possibility in the diagnosis.
"So we are beginning to evaluate the test in clinical service."
He said the test could enable researchers to find out how many people are infected with vCJD.
"In principle, it may allow us to find how many people in the population are infected so we can target risk management strategies and ensure the safety of our blood supply," he said.
"It could also enable us to make an earlier diagnosis and as treatments become available it is going to be desperately important to get to patients early before there is extensive damage to the brain."
Recent studies from tonsil samples suggest as many as 15,000 people in Britain might have the disease.
According to Health Protection Agency figures there have been 176 definite or probable cases of vCJD since it was first detected in humans in 1995.