Scientists reported new evidence on Friday which increased the likelihood that the human form of mad cow disease could be spread through a blood transfusion.
Britain announced last December what it said could be the world’s first case of variant Creutzfeldt-Jakob disease (vCJD) caused by transfusion, following the death of an unidentified patient several years after receiving blood from a donor later found to have had the illness.
British Health Secretary John Reid said at the time it was not certain whether the patient had been infected through the transfusion or by eating meat infected with mad cow disease.
But two studies published in The Lancet medical journal show infection through blood is a possible route of transmission.
“Our findings raise the possibility that this infection was transfusion-transmitted,” said Professor Robert Will, of the National CJD Surveillance Unit at Western General Hospital in Edinburgh, Scotland.
Variant CJD is the human equivalent of Bovine Spongiform Encephalopathy (BSE) or mad cow disease, an incurable, degenerative brain disorder linked to eating meat infected with BSE. The illnesses are caused by normal brain proteins, called prions, that transform themselves into infectious agents.
After studying blood donation records and the details of the case, Will and his team said the patient was much older than most vCJD sufferers and the odds of it not being through a transfusion were about one in 15,000-30,000.
In a separate study in the journal, scientists at the department of medical research at the French Atomic Energy Commission in France found that the macaque monkey can be infected with BSE orally or intravenously.
Experts not surprised
Based on their findings, they said blood transfusion should be regarded as a “likely route of contamination for vCJD patients with a medical history involving a transfusion during the period of risk.”
The recipient of the transfusion developed vCJD after a 6.5 year incubation period. The donor showed no signs of the disease when the blood was given to Britain’s National Blood Service but developed the illness and died from it three years later.
Professor Adriano Aguzzi, a leading expert on prion diseases at the University of Zurich in Switzerland, said the findings are not surprising because studies in sheep have shown that the infectious agent can be transmitted via blood, even if the blood is collected before symptoms of the illness are evident.
“Shocking as it may be, the finding that vCJD can be transmitted via blood transfusion is not surprising,” he said in a commentary on the research.
Up to December 2003, 153 cases of vCJD had been reported worldwide.
