THE FIRST experimental evidence that mad cow disease has been passed to humans is published today.
Scientists have discovered a critical similarity between the new type of Creutzfeldt-Jakob disease which has infected humans and bovine spongiform encephalopathy in cattle.
The finding adds powerful backing to claims that BSE has crossed the species barrier between cattle and humans.
The characteristic signature sets the new strain distinctly apart from other forms of CJD - but it is almost indistinguishable from the molecular hallmark of BSE.
Scientists see this as strong supportive evidence that the new CJD variant arose from BSE in beef.
The Government said last night that the findings did not require any additional measures to protect the public or restrict the consumption of British beef.
Roger Freeman, the minister co-ordinating the Government's response to the BSE epidemic, said present measures had been introduced after the new variant of CJD was first acknowledged earlier this year.
But Labour's health spokesman, Chris Smith, called for an immediate Government statement on the implications of the research, to be published in the magazine Nature.
Prof John Collinge, who made the discovery, called for his test to be used to find out whether scrapie, a similar disease in sheep, originated from BSE in cattle. "If BSE is in sheep it should be treated with the same respect as BSE in cattle," he said.
A team of scientists led by Prof Collinge at the Imperial College School of Medicine at St Mary's, London, examined the prion protein, the infectious agent that appears to cause BSE and CJD.
They developed a test that identifies the molecular differences between the strains of prion, and found that the prion present in patients with "new variant" CJD were almost identical to the prions found in cattle with BSE.