Vegan Health ArticlesParatuberculosis and Crohn's Disease: Got Milk? DNA Fingerprinting
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From Michael Greger, MD
Updated January 2001

Obtaining Crohn's tissue samples is easy -- patients are all too frequently having pieces of their bowel removed -- but growing MAP from this tissue is so difficult that a nonculture-based method was needed. This advance came in the late 1980s when new DNA fingerprinting techniques arrived on the scene.[70] Using DNA probe technology similar to that used in forensic cases to pick up minute amounts of DNA, one can determine the definite presence of paraTB without needing to actually culture and grow it.[144] No longer would researchers have to wait months or years for the spheroplasts to revert back to normal and start growing again, one could just target, with 100% certainty, MAP DNA.

Sixty-five percent of bowel samples from Crohn's patients came up positive, compared to only 4% of those with the similar but different disease ulcerative colitis.[170] As techniques for extracting and isolating DNA have become better and better, MAP has been found in intestinal Crohn's tissue with increasingly positive results.[112] The reason more Crohn's cases were not detected is because the test has a limited sensitivity, especially when searching for a needle in a haystack in the gut which is awash in the DNA of billions of other bacteria.[153] DNA probe detection of other low abundance bacterial pathogens, particularly in chronically inflamed tissues -- diseases like tuberculosis, Lyme disease, brucellosis, and lymphocytic leprosy -- have similarly been fraught with difficulty.[155] Isolating chromosomal DNA from mycobacteria in general is experimentally difficult.[154] There are also other substances in the gut that have been found to inhibit the test such as bile salts and polysaccharides.[192]

Also accounting for uncertainty in the data[27] is the frequent misdiagnosing of Crohn's disease. For example, it's been shown that at least 20% of people diagnosed with Crohn's actually have a different disease, such as ulcerative colitis.[186] There is also considerable debate on whether or not Crohn's is a single disease entity in the first place.[23] Crohn's may be more of a catchall syndrome describing a number of different conditions, some of which may not be caused by MAP.[132] Either way, this makes it difficult to interpret data that show that not all of those we consider to have Crohn's disease test positive for MAP.

As expected, some people without Crohn's -- healthy controls -- test positive. Yet just because someone comes in contact with and harbors a specific germ doesn't necessarily mean that person will come down with the disease.[65] It is estimated, for example, that only a third of calves that ingest MAP ever develop Johne's.26 It is also possible, like closely related subspecies, that there are different strains of MAP, some of which cause disease and some of which don't.[163] The important point is that there has consistently been a highly significant specific association between Mycobacterium paratuberculosis and Crohn's disease.[24]

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We began this archive as a means of assisting our visitors in answering many of their health and diet questions, and in encouraging them to take a pro-active part in their own health. We believe the articles and information contained herein are true, but are not presenting them as advice. We, personally, have found that a whole food vegan diet has helped our own health, and simply wish to share with others the things we have found. Each of us must make our own decisions, for it's our own body. If you have a health problem, see your own physician.