New 'mad cow' link to humans and livestock

'Mad cow' disease and the related human strain slowly wastes victims' brains

LONDON -- Seemingly healthy people and other animals could be silent carriers of "mad cow disease" and its human equivalent, new research has reported.

Research by British scientists found new evidence of a "sub-clinical" form of the disease -- officially known as BSE -- in mice which were infected but presented no symptoms.

The discovery could mean that key experiments into how easily BSE can move from cattle to infect people and other animals need to be reviewed.

Pigs, poultry and sheep could carry the sort of risk long associated with cows according to the laboratory research on mice and hamsters.

"Although they may not show any signs of disease, no matter how long they live, they could still harbour high levels of the infectious agent and therefore pose a risk," Professor John Collinge, who led the research team, said.

The disease, that slowly wastes the brains of its victims, is called Creutzfeldt-Jakob disease (CJD) in humans and scrapie in sheep.

Collinge said measures to protect people against BSE were adequate but the implications should be thought through.

"We should re-think how we measure species barriers in the laboratory. We should not assume that just because one species appears resistant to a strain ... they do not silently carry the infection," he said.

He added that the research also raised the possibility that apparently healthy cattle could harbour, but never show signs of, BSE.

The British government welcomed the research but said it had no plans to widen public health controls as a result.

"The measures we have in place address the possibility of transmission to humans and other animals," a spokesman for the Agriculture ministry said.

The government's scientific advisers will examine the new findings at a meeting on September 29.

Britain has reported more than 178,500 cases of BSE in cows and 70 people have died from CJD infection. Nine people in the UK are reported to be still alive suffering from the disease.

There have been two human deaths in France and one in Ireland.

The disease has led to a broad public debate about food safety and led to questions about how the government juggles consumer and farmer interests.

Sheep may also carry the deadly disease without showing symptoms

The British government has imposed a range of controls including a bar on older cattle being fed to people and a ban on cow and sheep remains being fed to livestock that ends up as meat for human consumption.

A range of new measures were also introduced to prevent the disease being transmitted via surgical instruments used in hospital or dental procedures.

Veterinary adviser to the British Meat and Livestock Commission, Tim Miles, said a sub-clinical form of the disease had been known about for some time which is why such stringent procedures were implemented.

"Any disease that we're seeing is a reflection of historical exposure. The public are completely protected through the current procedures," he said. The National Beef Association -- whose members were hard hit by BSE -- said the disease was now on the wane and that there was no need to pursue such "obscure areas" of research.

But the Human BSE Foundation, which represents victims' families, welcomed it as another piece in the "mad cow" jigsaw.

"The more we know about this disease the better," it said.

"It's a very worrying development that other species may be carrying this new hidden form of BSE and obviously poses yet another threat to human health."

The Agriculture ministry said it was confident the new research would not harm the public's confidence in eating meat.

"The public's confidence in British livestock is very high," the spokesman said. "In fact confidence in British beef is now higher, consumption levels are higher, than before the BSE issue."

Reuters contributed to this report.

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Britain's Medical Research Council
UK Ministry of Agriculture
Mad Cow Disease Home Page
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