Scientists discover new human link with BSE

British scientists today publish the strongest evidence so far that "mad cow" disease has been transmitted to humans through infected beef.

EU officials last night warned that the new findings ruled out even a partial lifting of the beef export ban in the foreseeable future and said that Britain must honour its obligation to slaughter all high-risk cattle.

Scientists from the Imperial College School of Medicine at St Mary's Hospital, London, have shown that a protein associated with the new variant of Creutzfeldt-Jakob disease (CJD) identified in humans earlier this year and tentatively linked with eating infected beef, closely resembles that seen in cattle with bovine spongiform encephalopathy (BSE), and in other animals infected with BSE. The protein, known as a prion, is quite distinct from that found in other forms of CJD. The research could lead to a new test to confirm the new variant of CJD.

These new findings are the first experimental evidence that the appearance of this fatal brain disease in humans is linked with the BSE epidemic in cattle. Twelve cases of the new CJD have been confirmed so far since March with two more suspected cases under investigation.

Professor John Collinge, a consultant neurologist who led the research, said yesterday: "The Government has been working on the assumption that BSE is a human pathogen [infectious agent] and this work strengthens that hypothesis."

A Department of Health spokeswoman called the findings "persuasive" but not conclusive.

Professor Collinge and his team analysed the biochemical properties of prion proteins associated with sporadic and acquired forms of CJD, new variant CJD, and BSE transmitted to mice, cats, and macaque monkeys.

According to their report in today's issue of Nature, they discovered a characteristic molecular signature in new variant CJD which was also present in BSE in cattle and other animals, but absent in other forms of CJD. Professor Collinge, a member of the Government's Spongiform Encephalopathy Advisory Committee, said identification of the marker would lead to a diagnostic test for new variant CJD using human lymph or tonsil tissue within six months, and a blood test within a year. Currently new variant CJD can only be confirmed at autopsy.

The Meat and Livestock Commission said the research had no implications for the safety of beef because safeguards were designed to protect public health from the "worst possible case scenario".