paratuberculosis, similar to other pathogenic mycobacteria, targets the mucosa-associated lymphoid tissues of the host ( 189). This occurs either by ingesting the organism through contaminated milk or food products or by accidental ingestion of the microorganism from contaminated surfaces ( 61). Young animals are most commonly infected through the fecal-oral route. Neonatal and juvenile animals are at the highest risk for acquiring an infection of M. paratuberculosis in human disease and the identification of potential sources of infection are topics of intense debate. paratuberculosis in milk ( 135, 136), others have demonstrated killing by turbulent-flow conditions ( 277). While some reports have indicated that high-temperature short-time pasteurization does not effectively kill M. paratuberculosis was more thermally tolerant than either Mycobacterium bovis or Coxiella burnetii, the current milk pasteurization standard microorganism ( 285). paratuberculosis in Crohn's disease.Īnother aspect of this controversy has surfaced recently with a report that in milk pasteurization trials, a clinical strain of M. ( 151) for a thoughtful analysis of the involvement of M. The reader is referred to a recent review by Hermon-Taylor et al. Finally, it has been hypothesized that only a subset of Crohn's disease cases have an infectious etiology ( 53). Similarly, chemotherapy with antimycobacterial agents has given mixed results in Crohn's disease patients (see references 61 and 151 for reviews). paratuberculosis and Crohn's disease has not been demonstrated. Given the difficulty that investigators have had in isolating a putative infectious agent for this disease from human tissues and the lack of suitable animal models, it is not surprising that Koch's postulates have not been fulfilled for Crohn's disease. This issue is still controversial, with several reports documenting either the presence or absence of this bacterium in Crohn's disease patients ( 36, 43, 58, 110, 167, 257).
paratuberculosis from intestinal tissue of Crohn's disease patients has led to concern that it may be pathogenic for humans ( 204). Nonetheless, a Johne's disease regression model estimates this loss to be from $40 to $227 per cow inventoried per year, based on the percentage of culled cows with clinical signs ( 219). However, accurately assessing losses in productivity and profit at the level of an individual herd is difficult, making it likely that the impact of this disease is underestimated nationwide ( 165, 223). It is considered to be one of the most serious diseases affecting dairy cattle ( 200). Its influence in the United States alone is staggering, causing an estimated loss of $1.5 billion to the agriculture industry every year ( 279). Johne's disease is prevalent in domestic animals worldwide and has significant impact on the global economy ( 290). paratuberculosis in the laboratory and reproducing the disease in experimentally infected cattle ( 46, 148). Trowt successfully fulfilled Koch's postulates by growing M. Frothingham initially reported the disease in Germany in 1894. paratuberculosis) is the etiological agent of a severe gastroenteritis in ruminants, known as Johne's disease. Bacteria of the genus Mycobacterium are gram-positive, acid-fast organisms that include a number of significant human and animal pathogens.
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