Fri 28 May 2004Breakthrough over BSE test
FORDYCE MAXWELLTHE use of an on-farm heartbeat test for cattle to identify early signs of BSE is imminent, it was claimed yesterday.
The test to measure millisecond variations in heartbeat intervals has been developed over eight years by Dr Chris Pomfrett and colleagues at Manchester Royal Infirmary.
These abnormalities, he said yesterday, can be detected long before the characteristic animal behavioural changes caused by prion diseases, the transmissible spongiform encephalopathies such as BSE.
He said: "Heart rate is controlled by nerve cells in the brainstem, the region at the base of the brain where the highest concentrations of prion protein are found in advanced cases of BSE when examined after death." Two parts of the brain are connected to the heart via the vagal nerve, which can react to slow down the heartbeat in times of stress.
"This function has been described as the vagal brake on the heart. What we see in cattle with BSE and humans with variant CJD [which has been linked to humans eating infected beef] is an intermittent action of the vagus, repeatedly cutting in and out in an abnormal manner."
He added: "Our test detects changes that precede the most sensitive clinical signs of BSE shown by cattle."
Equipment for on-farm use has been developed during more than 3,000 tests at Drayton experimental farm, Warwickshire, on cattle experimentally infected with BSE.
Pomfrett said: "It consists of three plastic stickers, about four inches across. These can be placed harmlessly anywhere on the side of the cow as long as they form a triangle and are connected to what looks like a big calculator for about five minutes. Then we have a result and know if the cow has BSE symptoms." He went on: "We started work on this in 1996 and applied for a patent in 1997. It could be on farms soon and become part of routine management."
Cases of BSE in UK cattle are now fewer than 1,000 per year compared with a peak of more than 180,000. But beef from cattle over 30 months old is still banned for human consumption and more than 3 million older cattle have been incinerated since the ban started in March 1996.