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JOHNE'S INFORMATION CENTER - University of Wisconsin Ñ School of Veterinary Medicine
JOHNE'S INFORMATION CENTER - University of Wisconsin - School of Veterinary Medicine

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Wednesday, October 17, 2018
New phage-based diagnostic test coming to market.

At the 2018 meeting of the European Association of Veterinary Laboratory Diagnosticians (14-17 October, 2018) Pelletier et al. reported on the use of a new phage-based assay called Actiphage™ Rapid kit from PBD Biotech to detect MAP in blood samples from bovine calves. Details are provided in the two page abstract (link below).

Comment: This report is interesting from two perspectives. The first is the biology of MAP infections in dairy calves. This the first report of MAP detection in blood samples of 3 different calves soon after birth; 1, 15, and 84 days of age for the three different calves. The calves reverted to test-negative after the single MAP detection. The second perspective is the promise of improved diagnostics for paratuberculosis using phages to enhance DNA extraction of MAP DNA from clinical samples to enhance the diagnostic sensitivity of real-time PCR assays for MAP.

EAVLD abstract


Tuesday, October 16, 2018
Survey of MAP infection in Canadian dairy herds

Colleagues at three veterinary schools in Canada teamed up to do the first all-Canada survey to estimate the prevalence of MAP infected dairy herds. The study collected samples from 362 dairy herds in 10 Canadian provinces using environmental fecal cultures as the diagnostic test.

True prevalence estimates were 66% for farms in Western Canada, 54% in Ontario, 24% in Québec, and 47% in Atlantic Canada. Herds housed in tie-stalls had a lower prevalence than freestall-housed herds, and herds with 101–150 and >151 cows had higher prevalence than herds with ≤100 cows. This was the first time MAP prevalence was determined using 1 detection method, performed in 1 laboratory, and within a single year across Canada, enabling direct comparisons of prevalence among regions, housing types, and herd sizes.

Comment: This was the first time MAP prevalence was determined using 1 detection method, performed in 1 laboratory, and within a single year across Canada, enabling direct comparisons of prevalence among regions, housing types, and herd sizes. The authors did an elegant job of judging the sensitivity and specificity of their sampling method. Their survey findings are similar those done in Europe and a bit lower than estimates for U.S. dairy herds.

Link to “in press” article:


Monday, October 15, 2018
Landmark paper defining Crohn’s disease (1932).

Eighty-six years ago today, Burrill B. Crohn, Leon Ginzburg, and Gordon D. Oppenheimer published a paper titled Regional Ileitis – A Pathologic and Clinical Entity in the Journal of the American Medical Association (vol. 99, no. 16, pp 1323-1329, October 15, 1932).

Honoring the importance of this report, the article was later reprinted as a Landmark Article in The Mount Sinai Journal of Medicine (vol 67, no. 3, pp 263-268, May 2006). We provide the original JAMA article here for users interested in reading this influential publication in its original form. Note: the reprinted version in the Mount Sinai Journal of Medicine has better print quality.

Comment: I appreciate history more as I grow older. Also, it is important to read original published reports to avoid misquoting or perpetuating misunderstandings. Interesting note: As described in Wikipedia, Crohn always preferred the medically descriptive terms "regional ileitis" and "regional enteritis" to "Crohn's disease", but he was not able to prevent the appropriation of his name for the disease.

Without providing much detail, B.B. Crohn’s article mentions efforts to determine if Mycobacterium tuberculosis was involved in the regional ileitis cases he described including culture for M. tuberculosis, inoculation of lymph node homogenates from five patients into guinea pigs, rabbits, and chickens, and acid-fast staining of tissue sections. He concludes that M. tuberculosis was not a cause of these cases of regional ileitis. However, he never mentions the 1913 report by Dalziel or makes any mention of Mycobacterium paratuberculosis or the similarities of regional ileitis in humans to that of cattle, as described by H.A. Johne in 1895. How might history be different had Dr. Crohn mentioned the possibility of M. a. paratuberculosis involvement?

The picture of B.B. Crohn is credited to Wikipedia.

Original article


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