The following is a transcript of

Farming Today

with Ashley Getting

As broadcast by: BBC Radio 4 on 31st March 2000

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Mr. Getting

Good morning. A bacteria that causes a deadly wasting disease in cattle could be passed to humans through milk. A special investigation by "Farming Today" has revealed that three pints in every hundred could be contaminated. Johne's disease is a wasting condition in cattle in which the intestines swell up, the livestock are unable to eat and ultimately have to be slaughtered. Johne's is now reaching epidemic proportions in almost every developed country in the world. It's caused by a bacteria that's known to the experts as Mycobacterium avium subspecies paratuberculosis or MAP for short. In the United States the bacteria is affecting a fifth of the national herd. In the Netherlands it's ravaging a quarter of dairy cows. Professor John Hermon-Taylor is a world expert in MAP, based at St. George's Hospital in London.

Professor Hermon-Taylor

What we know for certain is that MAP is widely prevalent in the domestic livestock of Western Europe and North America, and that there are also wildlife reservoirs, and that human populations -- that's us-- living in the same regions are certainly exposed to MAP.

Mr. Getting

There is a human disease also on the increase that is affecting up to eighty thousand people in the UK. Crohn's disease, like its animal counterpart Johne's, is a serious and incurable illness that attacks the intestines. It can have devastating consequences, as Crohn's sufferer Alan Kennedy explains.

Alan Kennedy

You might get somebody who would develop a fistula from the intestine to the skin, to the anus, to the vagina in women, and those tubules are outlets for septic fluids from the bacterial infection. So, as you can imagine, that's a very, very difficult thing to live with.

Mr. Getting

Carol Ann Courtney has struggled to live with Crohn's for years.

Carol Ann Courtney

Yeah, I'm suffering at the moment. I have just got out of bed after a particularly nasty night, which does involve a lot of bleeding, rectal bleeding, distension and extreme pain. And I've had many, many operations, you know, a lot of surgery, and it just causes -- you know, at the moment I'm pretty weak and wobbly, but that's because I've had two bad days of pain.

Mr. Getting

So, are these two diseases of the intestines, Johne's in cattle and Crohn's in human beings, linked by a common bacterial thread? Could Mycobacterium avium subspecies paratuberculosis or MAP be the missing link? Professor Michael Collins, president of the International Association for Paratuberculosis, says the evidence is striking.

Dr. Collins

In my reading of the literature where fully removed intestinal samples have been tested using genetic technology, seven out of ten studies find a significant association between this bacteria known as Mycobacterium paratuberculosis and the patient having Crohn's disease.

Mr. Getting

So, is there a common source? Is the animal one the same as the human one?

Dr. Collins

A difficult question. The science of DNA fingerprinting as it's called commonly to track which strains exist in which kinds of animals is still in its infancy. Workers in the Czech Republic perhaps have the most sophisticated system reported to date, and they have shown that, by their methods, some of the strains isolated from humans are identical with some of the strains isolated from cattle.

Mr. Getting

If there is a bacterial connection between the reservoir of Johne's in cattle and Crohn's sufferers like Carol Ann Courtney, then how could MAP be infecting the human population? Professor John Hermon-Taylor believes the infection is carried in our milk supply.

Professor Hermon-Taylor

We carried out ourselves an extensive, and I have to say rather exhausting, research project here between 1990 and 1994 that was supported by Ministry of Agriculture and by Action Research, and this showed unequivocally that MAP was present in retail milk. Now recent research also supported by MAFF carried out at the Queens University of Belfast, confirms that live MAP is, from time to time, present in units of retail pasteurised milk, and this is because subclinically infected dairy cows secrete MAP in their milk. It is almost as if the bug seeks out the reproductive pathway to pass from parent to offspring when the calf or the lamb or the child is most susceptible. So, it's definitely in the milk supply.

Mr. Getting

A spokesperson for Queens University in Belfast has confirmed to "Farming Today" that live MAP has been found in pasteurised milk, and the test is being done for the Ministry of Agriculture, although the report won't be finished for four months. So, if this year alone another 8,000 new Crohn's victims are going to be infected with an incurable disease that could be transmitted through milk, then why is so little being done? In 1992, eight years ago, Professor Hermon-Taylor alerted MAFF to the problem. Ministers said there wasn't enough evidence. In 1998 he delivered a new study to ministers; this time they responded. The pasteurisation process designed to make milk safe and kill off bugs like MAP was extended from 15 to 25 seconds, but it wasn't compulsory. David Balfour is from the National Dairy Council.

David Balfour

The industry did take the precautionary move, however, it is not possible to insist that everybody does it, as pasteurisation is subject to UK and EC law, and only by making that change could everybody be forced to make that move which we have taken, but it is merely, merely precautionary.

Mr. Getting

Well, shouldn't everyone be forced to make that move?

Mr. Balfour

I think that is a decision that should be taken by a government on the available evidence. Certainly, the Department of Health have looked at this evidence over the years, certainly since 1992. A panel of experts recently looked at it again. They said that the theory was unproven, and they did not recommend a change to anybody's dietary habits.

Mr. Getting

Well, doesn't it make a mockery of a serious precautionary move if some people still are going on in the same old way?

Mr. Balfour

There are a number of processes, many hundreds throughout the country. The vast majority have made the change. Fifteen seconds is still the internationally accepted holding time; it is the standard that is adopted throughout the world. And you cannot force, unless government demands it, that everyone makes the change. One can merely recommend it to one's members that that should be the case.

Mr. Getting

So, is this voluntary code enough when studies from Northern Ireland suggest up to 3% of the milk we drink could be infected by MAP? David Balfour says that the voluntary code is enough because the link between Johne's and Crohn's has not been proved. I asked Professor Michael Collins from the International Association for Paratuberculosis how much more proof is needed.

Dr. Collins

That's a good question. Not being a member of the medical or gastroenterology community, I guess you'd have to ask them how much proof is considered necessary to consider this, in fact, a causal association.

Mr. Getting

Well, do you think it is?

Dr. Collins

I'm of the opinion that Mycobacterium paratuberculosis is involved. My reading of the literature suggests that treatment of that infection for that subset of Crohn's patients will effect significant clinical improvement.

Mr. Getting

Despite growing evidence that the MAP bacteria in cattle could be responsible for Crohn's in humans, precious little research has been done on the likelihood of transmission through other dairy products like cheese or even through meat. And researchers now claim that MAP can be transmitted in ways that are even more direct than milk. A cluster of Crohn's cases in Cardiff prompted an investigation into the nearby River Taffe by Professor Roger Pickup from the Institute of Freshwater Ecology.

Professor Pickup

We came down on several occasions, and the samples returned a positive result for the presence of mycobacteria.

Mr. Getting

Well, how did it get from the river to create a cluster of disease?

Professor Pickup

Our hypothesis at the moment is that as the river travels through Cardiff, aerosols, or tiny droplets of water, are produced, and these are windblown and windblown into the population. They will then breathe those droplets in.

Mr. Getting

Although water from the Taffe isn't used for drinking, those potentially infectious water droplets that flow in our rivers are also flowing in and out of the lakes and reservoirs that supply our drinking water. And if MAP can survive the pasteurisation process in milk, can it also survive the parallel precautions taken with our tap water, filtration and chlorination? Professor Roger Pickup again.

Professor Pickup

There's a good chance it will . It's quite a strong organism. It's very difficult to break it open for DNA studies, and so, there is a good chance it could get through the water purification system. Other organisms of a similar type do.

Mr. Getting

So, faced with an incurable disease that could be affecting tens of thousands of people in Britain that could be transmitted through the most direct of means, water and milk, and that may be immune to current protection measures, Professor John Hermon-Taylor wants to know why we are doing so little about it.

Professor Hermon-Taylor

The average cost per year is somewhere in the region of 2,800 to 3,000 pounds a year, and you only need the back of an envelope to take eighty thousand times two thousand eight hundred a year and you can see what it's costing our health services each year, rising at the rate of the number of new people developing the disease, and that rate is increasing.

Mr. Getting

And despite that annual cost, over 220 million for the human population alone, not counting the cost of farming from sick livestock, the disease remains officially ignored. It's not even notified, as the official jargon has it, as being worthy of attention. And the small sums that might lead to more understanding of the bacteria and to a vaccine or a cure aren't currently available.

Announcer

You can hear more on the story on "CountryFile" on BBC 1 at 11:30 on Sunday. And on Monday's "Farming Today" we'll ask the "powers that be" why they're not doing more.