A third case of vCJD linked to a blood transfusion has been diagnosed.
VCJD first emerged in 1995
The patient, whose details are not being revealed, developed the brain disease eight years after receiving the blood from a donor who later got vCJD.
The patient, who is being cared for by specialist doctors, is one of a group of under 30 people known to have received blood from infected donors.
Infection experts said the case was "further evidence" the incurable brain disease could be passed via blood.
The first case of vCJD transmission by blood trasfusion was announced by then Health Secretary John Reid in December 2003.
But the latest case illustrates that the prions that cause vCJD can be incubated for many years before symptoms become apparent.
Since the first case was announced anyone who has received a transfusion since January 1980 has been excluded from donating blood as part of measures to protect the blood supply.
In 2004, the government wrote to thousands of people warning they may have been exposed to vCJD through contaminated blood products.
A group of under 30 have been identified as actually receiving blood transfusions from infected donors.
Most of the people warned were haemophiliacs, who are given plasma products, clotting factors used to treat their bleeding disorders. However, all the blood transfusion cases to date have not involved plasma products.
Professor Peter Borriello, director of the Health Protection Agency's centre for infections, said: "The occurence of a third case of vCJD in a small group of patients like this suggestes 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."
He added the people who had received blood transfusion from donors who later developed the disease have been informed of the development.
Dr Angela Robinson, medical director of NHS Blood and Transplant, said: "Our thoughts go out to the patient and their family."
Some 154 people have died from vCJD since it first emerged in 1995. The disease is believed to have passed from cattle to humans through meat infected with the disease BSE