Twenty four people accidentally given blood transfusions contaminated with the human form of mad cow disease are now at "substantial" risk, an expert has said.
Professor John Collinge, from the Medical Research Council's Prion Unit, made the assessment after investigating the third case of a person known to have acquired variant Creutzfeldt Jakob Disease (vCJD) from a blood transfusion.
Writing in The Lancet medical journal, he said blood transfusions seemed to be an efficient route for transmitting the infectious prion proteins believed to cause vCJD.
The first two cases of vCJD infection linked to transfusions were reported in 2004.
Both patients had received blood from donors who later developed the disease. One recipient developed signs of vCJD after six years, and died 13 months later.
The second did not develop symptoms and died from an unrelated cause five years after the transfusion. A post-mortem examination then revealed evidence of vCJD.
The third patient, a young man of 23, was the first to be diagnosed with the brain disease while still alive.
Like the others, he was given blood from a donor who later developed vCJD. Seven-and-a-half years after his transfusion he was referred to the NHS National Prion Clinic at the National Hospital for Neurology and Neurosurgery in London. There, his symptoms were confirmed to be caused by vCJD.
The patient joined a drug trial testing a potential treatment for the disease in 2004, but died a year later aged 32.
Initially 66 transfusion patients were known to have received infected blood from donors who developed vCJD. Today a total of 24 remain alive, but face an uncertain future.
