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Final Conclusion of Research Part 2

© Susan Johnson

Crohn's Disease Past, Present & Future    In the beginning...       The search for the cause of Crohn's Disease is truly a medical "who-done-it."  The first detective to try to solve the mystery began sleuthing in the early part of the twentieth century. Dr. Thomase K. Dalziel of Glasgow, Scotland, suspected that this human intestinal disease had something in common with a similar disease in cattle caused by a slow-growing bacterium called Mycobacterium avium subspecies paratuberculosis "MAP".  Applying the same test to diseased human tissue that successfully found the bacterium in animals, Dr. Dalziel found - nothing! Not a trace of the bacterium.  Why not?  Medical Science in 1913 couldn't answer that question.

Enter the next detective: Dr. Crohn.      In 1932, Dr. Burrill B. Crohn researched the disease that now bears his name.  He too could find no evidence of a bacterial origin for Crohn's Disease.  Consequently, Crohn's disease has, for over fifty years, been classified as an autoimmune disease with an unknown cause.  From this point on, most doctors concentrated their efforts on treating patients with maintenance therapies as the disease slowly destroyed the intestinal tracts of it's victims.

But one doctor wasn't satisfied      Dr. Walter R. Thayer, Jr., a professor at Brown University Medical College in Rhode Island and a practicing gasteroenterologist specializing in Crohn's disease continued to research MAP as a cause of Crohn's.  Dr. Thayer approached Dr. Roderick Chiodini, who had been working with MAP in cattle.  Thayer believed that an infectious agent might be the true cause of Crohn's disease.  Could Dr. Chiodini help find it?

Chiodini's finding:  Mycobacterium avium subspecies paratuberculosis in humans - and a surprise!      An authentic secret agent, this elusive bug turned out to have a "cloaking device."  When MAP settles into a human intestinal tract, it sheds it's tough, waxy shell, mutating into what's called a "spheroplast" form.  In this form, it cannot be detected by traditional testing methods, which is why Dr.'s Daziel and Crohn couldn't find it. Drawing on his expertise with mycobacteria, Dr. Chiodini was able to culture this sneaky intruder causing it to revert to its original "bacillary" form - thereby revealing its true nature.

And now we lift its fingerprints...     ...DNA fingerprints, that is.  In 1985, a gene sequence was discovered which is unique to MAP.  The sequence is known as IS900, and about 20 copies of the sequence are present in the MAP genome.  The gene sequence is not present in any other known organism, meaning that IS900 is a unique genetic "fingerprint" for MAP.

    In 1991, Prof. John Hermon-Taylor, of St. George's Hospital Medical School in