LONDON – A test for variant Creutzfeldt-Jakob Disease (vCJD) is available to British patients for the first time, according to the NHS National Prion Clinic, part of the University College London Hospitals Trust. Researchers say the blood test will help identify people infected with the human form of bovine spongiform encephalopathy. Until now, the only way to confirm a diagnosis of vCJD is through tonsil biopsies or from brain samples taken after a patient has died.

Prion diseases can exist in carrier states, meaning a person can be infected with prions, but not show any signs of disease in their lifetime. The blood test allows doctors to make a diagnosis at an earlier stage in the diseases' progression. Blood transfusions or blood products such as plasma clotting agents or purified antibodies can transmit vCJD. The test may allow for the medical community to screen donated blood, researchers said.

The Medical Research Council Prion Unit and the National Prion Clinic developed the blood test. Researchers said the test is at an early prototype stage but correctly identifies the "large majority of patients" with symptoms of vCJD and has not given false positives in patients with other brain diseases or healthy individuals. The Lancet will publish details of the test Feb. 3.