World Health Organization Shares Concern
GENEVA (Reuter) - The World Health Organization said Thursday groups of
people at risk from the human form of madcow disease should not donate blood.
Clarifying earlier confusion over the risk of the disease's transmission by blood transfusion or blood products, WHO said there had been no proven evidence of this.
The fatal brain disorder Creutzfeldt-Jakob disease (CJD) is the human form of bovine spongiform encephalopathy (BSE), or mad cow disease.
``Although there has been no proven or even probable instance of CJD transmission from human to human by blood transfusion or blood products, observation must continue,'' it said. ``The experts concluded that blood transfusions continue to be safe.''
But the WHO statement, which followed a two-day consultation with a group of 50 international medical experts that ended Wednesday, said three groups of people at risk from the disease should be barred from giving blood.
These were people who received growth hormones in the early 1980s, people who received a transplant of a human brain tissue called dura mater (the outermost and toughest covering of the brain, used in neurosurgery to patch damaged membranes of patients and extracted from corpses that died from CJD) and members of families affected with the disease.
A senior WHO specialist, David Heymann, said CJD struck about one person in one million, but that WHO was recommending a ban on blood transfusions by high-risk groups to be on the safe side.
``The disease agent has never been shown to be passed on by blood transfusion. This risk is zero, but we want to eliminate groups of people that are possibly at risk to be absolutely safe,'' he told Reuters.
WHO's recommendations followed laboratory experiments by Paul Brown, a U.S. scientist, that showed a small risk of CJD transmission through blood plasma in mice injected with the disease.
Brown said at a WHO news conference Wednesday he had injected blood from mice infected with the human form of mad cow disease into the brains of healthy mice, which became ill.
WHO is coordinating world-wide surveillance on the two diseases amid fears that mad cow disease can cross over to humans in a new form of the brain-wasting CJD.
But Heymann stressed there was no evidence that anyone had ever been infected with CJD through blood transfusion.
Brown, of the National Institutes of Health, Bethesda, Md., said dura mater was still being used in neurosurgery and other operations such as replacement of eardrums and intestinal surgery and in gall bladder, and that this had to be stopped.
Scientists think BSE and CJD are caused by mutated prions, brain proteins that can somehow replicate themselves and affect normal prions. They are not destroyed by regular cooking or freezing processes.
CJD is a painful degenerative disease which gives an infected patient involuntary spasms that then deteriorate into blindness and epilepsy. There is no known treatment or cure for BSE in bovines or CJD in humans.