But one London professor believes that the disease is caused by a bacterium that can be found in the milk being poured into beakers and breakfast bowls across the land every morning. And he is not the only expert who feels that Infliximab is just another treatment that suppresses the symptoms of Crohn's disease but does not tackle its causes.
Crohn's disease most commonly affects the small intestine and colon, causing ulceration along the gut that results in intense pain, diarrhoea, bleeding, weight loss and tiredness. For most Crohn's sufferers, the best they can hope for is steroids or anti-inflammatory drugs such as Infliximab. However, even with this treatment about 75 per cent of patients still require surgery at some stage in their lives, and even surgery does not cure the disease.
John Hermon-Taylor, professor of surgery at St George's Hospital in London, who has a special interest in molecular and cellular science, believes the causes of Crohn's disease are staring us in the face. He has been working on the disease since the Seventies and believes it is caused by an organism called Mycobacterium para-tuberculosis (M paraTB), which is also responsible for Johne's disease in cattle and sheep.
"The bug, which is very similar to tuberculosis, is found in domestic species and wild animals all over Europe and North America and has increased significantly over the course of this century because of intensive farming methods. It has learnt to live in the intestines of animals and causes chronic inflammation of the gut," he says. "The bug is then shed by the infected animals into their milk, which is passed on to humans.".
A recent study funded by the Ministry of Agriculture, Fisheries and Food (Maff) showed that out of 31 cartons of milk from 16 pasteurisation plants, six cartons tested positive for M paraTB. "If we want to get rid of M paraTB in milk, we need to be pasteurising milk at a higher temperature than we do for TB," says Prof Hermon-Taylor.
"As for the treatment of Crohn's, although the bug is similar to TB it is not affected by anti-tuberculosis drugs. However, we have discovered that this bug can be successfully killed off with a combination of two specific antibiotic drugs, rifabutin and clarithromycin. This treatment is effective in 80 per cent of all cases of Crohn's disease."
Prof Hermon-Taylor's research has been duplicated in Houston, where Dr David Graham conducted a controlled trial looking at the efficacy of clarithromycin as a treatment for Crohn's. They randomly assigned 17 people with severe Crohn's to receive either simple conventional therapy, or therapy with antibiotics. Forty per cent of the patients on antibiotics became well and stayed well for up to three years.
So why is medical opinion so divided on the causes of Crohn's disease and its treatment? One reason is that M paraTB is almost impossible to detect, as it "hides" within human cells.
"You can't see it down a microscope or culture it in a laboratory, and immunological tests don't detect it either," says Prof Hermon-Taylor. "The only way you can detect it is by revealing the presence of its DNA, and even then the test has to be done extremely accurately."
Dr Derek Jewel, senior gastroenterologist at the John Radcliffe Hospital, Oxford, is sceptical about Hermon-Taylor's research. "Professor Hermon- Taylor's original paper showed up M paraTB in about two-thirds of patients with Crohn's disease, but the specificity of the trial was questionable. Although his work seems very convincing, the concern is that the test has never successfully been repeated. Some very reputable people have tried to detect the DNA in the tissue but just cannot do it," he says.
But Prof Hermon-Taylor is adamant that his studies have been repeated successfully elsewhere. "Since 1992 there have been 18 other studies using the DNA test on Crohn's and nine say it's there and nine say it's not. And all the doctors are arguing like a tree full of parrots."
However, at the University of Central Florida researchers have now perfected a blood test for M paraTB in human beings, and in a recent study 92 per cent of people with Crohn's tested positive.
One person who is in no doubt about the link between M paraTB and Crohn's disease is Lesley Lane. Ten years ago her son Jordan was out playing football with his mates. When he came indoors he had a swelling on the side of his neck. The GP diagnosed infected lymph nodes. But after two weeks he was taken to Addenbrookes Hospital in Cambridge for tests.
"I was told he had Hodgkin's lymphoma and signed the form to remove the lump," says Lesley. "Three days later they told me it wasn't Hodgkin's, but a form of TB."
A few weeks later the lump came up again and they removed it. Jordan was put on anti-tuberculosis drugs but they didn't work. He had to have more lumps removed and then he seemed fine until 1993, when he suddenly started to get severe abdominal pain and diarrhoea. He lost weight rapidly and was tired and listless. "He looked as if he was wasting away," says Lesley. He was referred to a paediatrician, Dr Nick Barnes, at Addenbrookes. "He recommended we go and see Prof Hermon-Taylor. When he asked me if I was prepared to travel, I said I would go to the ends of the earth if it would make Jordan better."
Prof Hermon-Taylor had already been sent a sample of tissue from Jordan's lump. "He showed us some pictures of cows and pointed to one in particular that looked particularly sick and anorexic. He then explained that the DNA from the cow matched the DNA from Jordan's lump, and told us he thought that Jordan had Crohn's caused by M paraTB. It was the first time anyone had explained Jordan's illness in a way that made perfect sense," says Lesley.
"He told us that the combination of these two antibiotics would cure the problem, but Jordan was never allowed to drink cows' milk again. He was totally honest about the drugs. They had only ever been tried on adults, and they could make Jordan feel ill. But Jordan was so keen to get well, he was prepared to try anything."
Today, Jordan is a strapping 17-year-old, in his first job as a trainee accountant. "From being a thin and wasted young lad, he is completely healthy, and has never drunk cows' milk again. I would advise anyone who has Crohn's to give this treatment a try. I am totally in Prof Hermon- Taylor's debt," says Lesley.
Dr Barnes is also delighted with Jordan's progress. "Jordan is living proof that M paraTB can cause Crohn's disease, and that it can be killed off with these drugs. Far from being a rare case, I believe we are seeing more and more M paraTB in the community. My wife is a GP in a practice of around 14,000 patients. Out of the 25 who have Crohn's disease, at least half have a story similar to Jordan's which can be traced to M paraTB," says Dr Barnes. "If I got Crohn's disease today, I would go on the drug treatment like a shot."
Prof Hermon-Taylor has the last word. "We know that in 1999 about 4,000 people will come down with Crohn's disease, which will ruin their lives. In the first half of this century, we dealt with TB in cattle. It's time we now dealt with M paraTB before it becomes an epidemic," he says.
For further information on Crohn's disease contact the National Association for Colitis and Crohn's Disease on 01727 844296Reuse content