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The BBC's Catherine McGourty
"Food experts are playing down the risk"
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Professor John Collinge
"Subclinical forms of disease could be seen in other species"
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Tuesday, 29 August, 2000, 08:28 GMT 09:28 UK
BSE risks played down
cow at incinerator
Infected cattle were destroyed to control the disease
Fresh fears that BSE, or mad cow disease, could enter the human food chain by infecting pigs, sheep and poultry have been played down by food safety experts.

Scientists discovered that BSE could infect different species without them showing any sign of carrying the illness.

It had been thought that the species barrier made it difficult for BSE to pass to different species of animals.

But some experts believe the findings do not present any new dangers for humans and believe current public health measures are adequate.

Scientists from the Medical Research Council Prion Unit, based at St Mary's Hospital, west London, discovered proof of a so-called sub clinical form of BSE where animals could be infected but show no symptoms of the disease.

We are now in the end games for BSE

Prof Hugh Pennington
They injected material from BSE-infected hamsters into mice.

Mice have always been thought to have an effective barrier against the disease.

Although the animals showed no signs of illness, the researchers found they had high levels of potentially lethal abnormal prions in their brains.

Prions are the infectious agents in the disease.

Professor Andrew Hill, of the Medical Research Council's Prion Unit, said the research showed it was necessary to re-examine the way species barriers are measured in the laboratory.

"Perhaps we should not assume that because one species appears resistant to a strain of prions it has been exposed to that it doesn't silently carry the infection," he told BBC Radio 4's Today Programme.

'Reinforcing knowledge'

"It raises the theoretical possibility that apparently healthy cattle could harbour but never show clinical signs of BSE."

He said it was important to repeat the research using different strains of prions.

"The results we obtained were quite unexpected and it means we have to re-evaluate the way we study these species barriers," he said.

Hugh Pennington, professor of bacteriology at Aberdeen University, played down any new fears.

"We are now in the end games for BSE," he told the Today programme.

"We already know that the agent can move from one species to another, unfortunately it has done that to people," he said.

"He is reinforcing what we know already."

Members of the Spongiform Encephalopathy Advisory Committee (SEAC) are to consider the findings at their next meeting on 29 September.

Professor Peter Smith, acting chairman of SEAC, said: "It is not clear that the new findings indicate that additional controls should be considered with respect to protecting human or animal health."

'Worrying development'

But Malcolm Tibbert, acting chairman of the Human BSE Foundation, that represents families of people who died of CJD, said the latest research was a very worrying development.

"Other species may be carrying this new hidden form of BSE posing yet another threat to human health," he told the Today programme.

"The more that we know about this disease the better and hopefully we can go on to have a better understanding of it," he said.

Variant CJD, which first emerged in 1996, is now known to be BSE in a human guise. It is thought to have spread to the human population through people eating contaminated beef products in the 1980s.

A total of 79 cases of variant CJD have been recorded so far.

The scientists, led by Professor John Collinge, say there could be "important public health implications" for their findings.

Their research is published in the journal Proceedings of the National Academy of Sciences.

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See also:

01 Aug 00 | UK
Europe snubs British beef
17 Jul 00 | Health
Baby food firms deny mad cow risk
15 Jul 00 | Health
CJD scientists probe abattoirs
29 Jun 00 | UK Politics
BSE fears after cow infected
20 Jun 99 | BSE Inquiry
BSE: The long search for the facts
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