Mycobacterium Avium sub-species Paratuberculosis
Diagnosis of Paratuberculosis (Johne’s Disease)
Collins, M.T. (2011). Diagnosis of paratuberculosis. Veterinary Clinics of North America: Food Animal Practice, 27(3): 593–598. The emergence of paratuberculosis as a common and costly problem affecting multiple ruminant species led to a surge in research funding internationally, which in turn led to development and validation of multiple diagnostic tests. Today, there are available a greater diversity of accurate and affordable tests for paratuberculosis than for most other ruminant infectious diseases, including brucellosis and tuberculosis, 2 diseases that have been virtually eradicated from most developed countries. There is a suitable diagnostic test for virtually every paratuberculosis testing need. The present-day challenge for practitioners is to select the appropriate test for the intended purpose.
Six‑Year Field Trial of Johne’s Disease Control in Dairy Herds
Collins, M.T., Eggleston, V., Manning, E.J.B. (2010). Successful control of Johne’s disease in nine dairy herds: Results of a six-year field trial. Journal of Dairy Science, 93: 1638–1643. The objective was to evaluate if a standardized Johne's disease control program significantly reduced the prevalence of cattle infected with Mycobacterium avium ssp. paratuberculosis in dairy herds with a moderate to high initial infection prevalence of ≥10% ELISA-positive adult cattle. Nine Wisconsin dairy herds of diverse sizes and management styles completed the 6-yr study. Although variations among farms were observed, the collective results demonstrated that bovine paratuberculosis can be controlled in dairy herds through effective heifer husbandry practices in combination with diagnostic testing to identify, for culling or management, cows most likely infectious.
Seroreactive MAP Proteins in Human Isolates (Crohn’s Disease Connection)
Shin, A.R., Kim, H.J., Cho, S.N., Collins, M.T., Manning, E.J., Naser, S.A., Shin, S.J. (2010). Identification of seroreactive proteins in the culture filtrate antigen of Mycobacterium avium ssp. paratuberculosis human isolates to sera from Crohn's disease patients. FEMS Immunology & Medical Microbiology, 58: 128–134. The etiology of Crohn’s disease (CD) is unresolved, but it is likely that an interplay of host genetic factors and environmental triggers is relevant. Mycobacterium paratuberculosis (MAP) has been focused upon as one of these triggers because it causes a similar chronic inflammatory bowel disease in animals. However, the differences among MAP antigens isolated from humans (H-MAP) and cattle (BMAP) have not been well characterized. In this study, culture filtrate (CF) proteins from MAP isolates were tested with sera from CD patients and healthy controls in enzyme-linked immunosorbent assay (ELISA). Antibody produced by seven CD patients reacted differently according to the antigen source: strong reactivity was seen to H-MAP CF, but not to B-MAP CF. Six proteins, ModD, PepA, transaldolase, EchA9, MAP2120c, and MAP2950c, in H-MAP CF reacting specifically with CD patient sera were identified by liquid chromatography-electrospray ionizationMS. Bioinformatic analysis revealed that ModD and PepA were the same proteins reacting with sera from cattle infected with MAP. The elevated antibody responses of CD patients to rModD and rPepA were confirmed by ELISA (P o 0.001). These results support previous studies showing ModD and PepA as key antigens for the diagnosis of MAP infections. The study also identified additional proteins potentially useful in the design of assays for human MAP infections.
Putting Crohn’s on the MAP: Five Common Questions on the Contribution of MAP to the Pathophysiology of Crohn’s Disease
- Agrawal, G., J. Aitken, H. Hamblin, M.T. Collins, T.J. Borody. 2020. Putting Crohn’s on the MAP: Five common questions on the contribution of Mycobacterium avium subspecies paratuberculosis to the pathophysiology of Crohn’s Disease. Digestive Diseases and Sciences https://doi.org/10.1007/s10620-020-06653-0
For decades, Mycobacterium avium subspecies paratuberculosis (MAP) has been linked to the pathogenesis of Crohn’s disease. Despite many investigations and research efforts, there remains no clear unifying explanation of its pathogenicity to humans. Proponents argue Crohn’s disease shares many identical features with a granulomatous infection in ruminants termed Johne’s disease and similarities with ileo-cecal tuberculosis. Both are caused by species within the Mycobacterium genus. Sceptics assert that since MAP is found in individuals diagnosed with Crohn’s disease as well as in healthy population controls, any association with CD is coincidental. This view is supported by the uncertain response of patients to antimicrobial therapy. This report aims to address the controversial aspects of this proposition with information and knowledge gathered from several disciplines, including microbiology and veterinary medicine. The authors hope that this discussion will stimulate further research aimed at confirming or refuting the contribution of MAP to the pathogenesis of Crohn’s disease and ultimately lead to advanced targeted clinical therapies.
Additional Scholarly Contributions
Dr. Collins also served as Guest Editor for an entire scientific volume dedicated to Johne’s disease:
Veterinary Clinics of North America – Food Animal Practice (Johne’s Disease Issue)
Collins, M.T. (Guest Editor). (2011). A 143‑page, 13‑chapter volume focused exclusively on Johne’s disease.
This issue of Veterinary Clinics of North America: Food Animal Practice captures this wealth of new knowledge about Johne's disease and translates it into practical terms for veterinary practitioners. Authors of the enclosed articles are internationally recognized experts who work with practitioners and producers on a daily basis, giving them insights on Johne's disease only gained by years of experience and considerable trial and error. This issue provides a basic understanding of Johne's disease epidemiology and pathobiology, practical methods for Johne's disease control on farms, early information on genetic resistance, a description of national and international control efforts, and a glimpse into the future as to whether MAP is a human health issue: a zoonotic pathogen contaminating foods of animal-origin.