A third case of variant-CJD - the human form of mad cow disease - associated with a blood transfusion has recently been diagnosed in Britain, the country’s Health Protection Agency (HPA) reported on Thursday.

“The patient developed symptoms of vCJD about eight years after receiving a blood transfusion from a donor who developed symptoms of vCJD about 20 months after donating this blood. The patient is still alive and is under the care of doctors at the National Prion Clinic,” the agency said in a statement.

Professor Peter Borriello, Director of the HPA’s Centre for Infections said: “The occurrence of a third case of vCJD infection in a small group of patients like this suggests that blood transfusion from an infected donor may be a relatively efficient mechanism for the transmission of vCJD, although much still remains unknown.

“This underlines the importance of the existing precautions that have been introduced to reduce the risk of transmitting vCJD infection through blood transfusion.”

The agency stressed that all three cases of vCJD relate to the transfusion of blood components and not treatment with plasma products.

The latest patient is one of a small number (less than 30) of living individuals who are known to have received a blood transfusion in the UK from a donor who later developed vCJD.

All these individuals have previously been informed of their potential exposure to vCJD and asked to take certain precautions to reduce the chance of passing on vCJD on to other people via healthcare procedures, such as surgery.