Grand Round: Mycobacterium paratuberculosis cervical lymphadenitis, followed five years later by terminal ileitis similar to Crohn's disease

Mycobacterium paratuberculosis was first described by Johne and Frothingham in 18951 as the cause of a chronic inflammatory disease of the intestine in a German cow. The organism was called Johne's bacillus, and the illness (in which millions of acid fast mycobacteria were visible in the diseased tissues), Johne's disease. In 1901 Thomas Dalziel, a surgeon at the Western Infirmary in Glasgow, operated on a colleague with chronic inflammation of the intestine. He was aware of the description of Johne's disease and of the subsequent bacteriological research in the field. He collected other cases and published his observations in the BMJ in 1913.2 He wrote that the “histological characters” of the disease he had described in humans were so similar to those of Johne's disease that the diseases may be the same. Dalziel's dilemma was that he could not see acid fast mycobacteria in the diseased intestine in humans.3 M paratuberculosis belongs to the M avium-intracellulare group.4 The term paratuberculosis suggests close similarity to M tuberculosis , but in truth it is very different. Unlike M tuberculosis , it can survive in the environment and is highly resistant in vivo to most standard antituberculous drugs. M paratuberculosis cannot be reliably detected by culture in the laboratory; different subtypes of the organism with different preferred hosts5 6 range from very slow growing to unculturable. M paratuberculosis can cause chronic inflammation of the intestine in many species of animals including primates.7 8 9 The disease in animals shows a broad range of histopathological types, from a pluribacillary (lepromatous) form with millions of typical acid fast bacilli visible in the tissues, to a paucimicrobial (tuberculoid) form in which M paratuberculosis cannot be seen in the tissues and cannot be detected by culture but in which there is …