Experiments with mice have shown that blood plasma is capable of transmitting the disease agent. This would also apply to the "new variant" of CJD (v- CJD), thought to be derived from the agent which causes bovine spongiform encepalopathy (BSE), or mad cow disease.
The work was carried out by Paul Brown, a leading scientist in both BSE and CJD based at the National Institutes of Health in Bethesda, Maryland. He injected blood from mice infected with CJD into the brains of healthy mice, which then became ill.
The implications of his work, which is not yet published, are that blood and blood products donated by people who subsequently die of v-CJD should be removed from blood banks.
But the UK National Blood Authority said last night that it was not notified of any such cases and has not been instructed to trace any donations from people who die of v-CJD.
However, it did tighten its rules on blood donation by families and relatives of CJD victims in August last year.
Meanwhile yesterday, the father of the fifteenth person to die in the UK of v-CJD - 19-year-old Matthew Parker, who died at the weekend - accused the Government of murder.
John Middleton said: "This has been a cover-up from day one. The Government knew it was giving infected feed to cattle and knew that would be passed into the human food chain. They have murdered my son and I want someone to be accountable for his death. Someone must stand up and admit it's their fault."
Two more Britons who have been diagnosed as having v-CJD are still alive. In total there are 17 recorded cases, compared with 10 at this time last year when the Government first announced the existence of a link between BSE and v-CJD.
Dr Brown's work has confirmed the fears of experts, who have long suspected that the prion protein which causes it could be transmitted in the blood.
But Dr John Barborough, microbiology consultant toe the NBA, who heard Dr Brown's talk, told The Independent: "It's dangerous to extrapolate from this. Injecting into the brain is a million times more effective as a transmission.
"But, being cautious, we will be looking at this in the NBA, and will watch out for anything that looks significant, and working with the Department of Health."
CJD victims, and people who have developed the disease from injections of human growth hormone, are also banned from donating organs.
But many of the victims of v-CJD develop symptoms quickly and die soon after showing clinical symptoms. It is also impossible to know if people are incubating the disease. The first victim of v-CJD in the UK was almost killed in a road crash, and might therefore have been a potential organ donor.
The blood of people who are incubating the disease would be potentially infectious. The prion protein eventually seems to concentrate in the brain and nervous tissue, where it leads to holes, which give the brain a spongy appearance.Reuse content