Mad Cow Experts Fear Second
Disease Phase In Humans

By Jennifer Cooke
The Sydney Morning Herald

Britain's second possible case of person-to-person transmission of the human equivalent of mad cow disease via a blood transfusion indicates a possible second phase of the epidemic in people.
What is even more worrying, experts say, is that the second victim - who received blood in 1999 from a person who later died of a new variant of Creutzfeldt-Jakob disease (vCJD) - belongs to a different genetic group to every other of the 150 vCJD victims to date.
This suggests that the disease may strike a wider group of people than those affected so far.
The second victim, whose spleen tested positive during a post mortem to the infectious agent that causes vCJD, died from an unrelated cause.
Professor Graeme Ryan, chairman of the Federal Government's expert committee on prion diseases, which include both vCJD and bovine spongiform enceophalopathy (BSE), said the fact that the agent was found for the first time in a spleen was interesting enough. However, the fact that the blood recipient was among a genetic group that comprises about 47 per cent of the world population was extraordinary.
The matter would top the agenda at the next meeting of the committee on Transmissible Spongiform Encephalopathies in Melbourne in several weeks.
In July last year the Red Cross Blood Transfusion Service acted pre-emptively by tightening blood donation restrictions already in place by further deferring anyone who had lived in Britain for more than a total of six months between 1980 to the present, as well as anyone who had ever had a blood transfusion in Britain.
Britain only barred blood transfusion recipients dating back to 1980 (the start of the BSE epidemic in cows) from donating blood this year.
This followed the detection of the first possible vCJD case via blood transfusion in December in a person who died of the disease six years after a blood transfusion from a donor who also later died from vCJD. The disease has an incubation period of at least a decade.
This second case raised important questions, Professor Ryan said, including whether the person would have developed vCJD and whether the person would have been a carrier for it before death, despite not having any symptoms.
"It's quite an extraordinary finding and very worrying too."
The first phase of the vCJD epidemic occurred in 1996 when the British Government announced the first group of people who had died of vCJD. It followed a decade of denials that eating beef products contaminated with BSE could jump from cows to humans.
More than 150 Britons and other people who lived in Britain during the peak of the BSE epidemic have since died of vCJD. This month a seventh vCJD victim was also found in France.
The head of Australia's CJD Registry, Professor Colin Masters, said this might indicate a second phase of the human epidemic, the first being the transmission from cows. "In Australia we have to continue to review the risk reduction measures taken so far and see if anything further is required."
Australian authorities have not recommended extending blood donor deferrals to those who have spent long periods in France and other European countries where BSE has spread.
So far vCJD has only involved a genetic group that makes up 38 to 40 per cent of the population.
More details are expected to be forthcoming when an article on the subject appears soon in the journal The Lancet.
Copyright © 2004. The Sydney Morning Herald.



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