After you've read this, there's another interesting article you should read, and yet another. Finally, there's a really excellent site dealing with this subject by Alan Kennedy.
The following article appeared in ia Journal number 140 (June-August 1993) and has been scanned in and reproduced here without permission. Any typographical errors are mine or my OCR software's.
Professor John Hermon-Taylor,
M Chir FRCS
St George's Hospital Meledical School, London
Throughout this century, Crohn's disease has become a progressively increasing problem, miserable for those who have it and, hitherto, baffling for the doctors. Many attempts have been made to find bacteria or viruses that might specifically cause the disease, but until recently all these efforts failed.
We now know that this is because the causative organisms are very difficult to identify by conventional means, refusing to grow in the laboratory and being undetectable by microscopy and general immunological tests. Ths breakthrough came in 1985 in the form of a discovery, in the Department of Surgery at St. George's Hospital medical School, of a small fragment of DNA in some `scum' that had taken up to five years to appear in a Crohn's disease culture. Rather like forensic testing, this enabled Crohn's disease bugs to be DNA fingerprinted. The researchers at St. George's then developed a very sensitive test for the detection of the fingerprinted organism, which turned out to be mycobacterium paratuberculosis. These tests have shown that the DNA of this organism is present in the diseased tissues, small gut and large gut of the vast majority of people with Crohn's disease, but not of ulcerative colitis.
This is very important because mycobacterium paratuberculosis can also cause chronic inflammation of the intestine in many different species of animals, including primates closely related to humans.
New research can nearly always be relied on to produce the unexpected, and this case was no exception. What the St. George's researchers found uas that about 10% of apparently normal people had a low level of mycobacterium paratuberculosis in the healthy colon, suggesting a previously unsuspected exposure of the populalion to these chronic enteric pathogens. How are these oranisms getting to us? Obviously food and water supplies are potential candidates.
There was also a followup article in ia Journal number 152 (June-August 1996) by David Eades (ia's national secretary) which revealed results of further study. Two thirds of those suffering from Crohn's in southern England had MparaTB present in their diseased tissues, compared with only 4% of those suffering from UC. The article also suggests that those with Crohn's disease might want to switch to UHT milk which is less likely to contain this robust mycobacterium.