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Fears humans could catch fatal cow virus

ANIMAL health experts in Scotland are investigating how to control a fatal wasting virus in cows amid fears it could be passed on to humans.

New data shows that the reported incidence in Johne’s disease in cattle in Scotland has nearly doubled in 10 years.

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The Food Standards Agency (FSA) has called for improved diagnosis and control of the disease as one Government sponsored survey estimates that up to 42.5% of dairy farms have been affected. It is concerned because some scientists have linked Johne’s to the human inflammatory bowel condition Crohn’s disease.

Thousands of cattle have died over the past decade after being infected by the intestinal disease. Figures obtained by The Herald show that in Scotland since 2000, when there were just over 400 reported diagnoses in cattle alone, the numbers have almost doubled in the past few years.

Veterinary agencies also report 52 diagnoses in sheep in Scotland in the first nine months of last year.

But there is concern that, in parallels with the mad cow disease outbreak 20 years ago, infected sheep and cattle are slipping through the net because it can be several years before any signs of the disease become obvious.

The disease is not notifiable, so many more deaths may not have been reported.

Cases of Crohn’s disease have been rising in the UK and it is estimated to affect more than 100,000 people, with between 3000 and 6000 new cases diagnosed each year. A study in Scotland found there had been a 50% rise over 10 years among under-16s.

There is no known cure for Crohn’s, whose symptoms are similar to that of Johne’s and include pain, diarrhoea, severe tiredness and loss of weight. It is often associated with other inflammatory conditions affecting the joints, skin and eyes.

Patients need treatment with drugs, including steroids, to reduce inflammation or by means of special liquid feeds to rest the bowel. Surgery can be required to remove narrowed or damaged parts of the intestine.

Professor John Hermon-Taylor, from St George’s Hospital in London, believes Johne’s disease is transferred to humans from cattle through food and believes it should be notifiable, ensuring it is reported to Government authorities to allow for a proper monitoring of the disease.

“The link between Johne’s and Crohn’s is that the proven multi-host bacterium, which causes chronic inflammation of the intestine, causes them both,” he said.

Researchers at the Scottish Agricultural College (SAC) have launched a bid to find the most cost effective approach to control the bacterium.

George Caldow, of the SAC, said there were possible implications for human health but there was “debate and differing opinion across the medical profession” about the link between Johne’s disease and Crohn’s.

“What it does do is raise the question mark,” he said. “The FSA has recommended that a precautionary principal is taken in the dairy industry to ensure that as little of the bacterium as possible can ever enter the food chain.”

The problem, however, is how to detect it. The Moredun Research Institute, Edinburgh, is trying to develop the first effective diagnostic test for the disease, emphasising the importance of control to Scotland.

Dr Karen Stevenson of Moredun said in a briefing about the research: “Johne’s disease is a major endemic disease and increasing in prevalence. Control of infectious livestock diseases will be integral to food security, public health and the sustainability of Scotland’s rural communities.”

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