WelcomeLink to Body ContentLink to Site Map
Select Area of Interest

Choose topic:
FAQs
Epidemiology
Pathology
Diagnosis
Control
Prevention
Herd/Flock Management
Laws & Regulations
True Cases & Stories
Gallery Graphics
Line
Testing Services
General Information
Glossary
History
Biology of Ml. Paratuberculosis
Antimicrobial Therapy
Zoonotic Potential
Test Your Knowledge
Handouts/Brochures
Presentations
Links
Line
Guestbook
Sponsors & Credits

Ask the Expert
Site Map
Search the Site

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




Search Site





Table Bottom

 



Comprehensive, reviewed, refreshed and renewed!

Testing Services

Questions about testing?
Call 608-263-6920

What's New    Bar



Bar
Monday, November 12, 2018
Ovine Paratuberculosis in Uruguay

Case Report:

Eleven cases of Johne’s disease are described in this case report. All originate from a 735 head flock of sheep in Colonia, Uruguay. Six animals had the multibacillary form of the disease (abundant acid-fast bacteria), and 5 had the paucibacillary form with minimal lesions. All animals were infected with the S-strain of MAP. This is only the second time the S-strain of MAP has been reported in South America, the other being from a sheep in Argentina.

Comment: This report has a lovely scanning electron micrograph of MAP inside macrophages, an excellent picture of the thickened intestine, and good histopathology images, both H&E stained and ZN-stained. The article notes that Johne’s disease is widespread in Uruguayan cattle but has not been documented as a problem in sheep until this case report. This report is newsworthy for documenting S-strain MAP infections in sheep in Uruguay and for the relatively young journal in which the report appears.

This is an open-access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Journal of Infection in Developing Countries, 12(3):190-195, 2018.


Bar


Bar
Tuesday, November 6, 2018
Comparison of two PCRs for diagnosis of paratuberculosis in sheep

Research Article

Julie Arsenault and colleagues just reported a comparison of PCR assays to detect MAP in fecal samples from ewes culled from 7 flocks in Quebec, Canada (see JVDI OnlineFirst, 02-NOV-2018, link below). This is a novel contribution to Johne’s disease research since there are not many reports of diagnostic test accuracy on sheep are available from animals in North America.

The case definition for being MAP-infected was based on isolation of MAP in culture from tissues and was met by 44 ewes in the study. Another 30 culled ewes from these same flocks were deemed not MAP-infected based on culture for MAP from tissues and histopathology. The in-house real-time IS900 PCR sensitivity (Se) & specificity (Sp) were 84% and 93%. By comparison, a commercial PCR kit (Tetracore) had values of 52% (Se) and 93% (Sp), assuming “suspect” classified samples were considered negative. The Tetracore Se & Sp values were 63% and 87% if suspects were classified as positive because Se goes up, but Sp goes down as you move the cut-off for defining a “positive”.

Other interesting observations: A commercial, ELISA had and Se/Sp of 14% and 100% on these same ewes further verifying that ELISA is not particularly useful when used on sheep. And among the ELISA-positive ewes 3 had multibacillary lesions (lots of MAP observed) and 1 had paucibacillary lesions (few or no MAP observed). Fecal culture Se was 21% (3 multibacillary and 2 paucibacillary).

Comment: Evaluation of diagnostic assays is tricky business. The case definition is crucial! This study used a standard, well-accepted case definition for MAP-infected sheep, i.e. the sheep considered as “cases” were culture-positive from mesenteric lymph nodes, ileum or feces. The trickier part is the case definition for not MAP-infected. While it is relevant to test animals residing in the same flocks as the MAP-infected animals, it is also important to test animals in flocks that are 100% certain to be MAP-free. This higher standard for not MAP-infected, testing MAP-free flocks, was not achieved in the study making specificity estimates questionable (acknowledged by the authors). Because PCR assays may be more sensitive than the “gold standard” used to define not infected ewes there may be instances where the PCR was correct and the case definition for being not MAP-infected was wrong. And, the study was relatively small making the 95% confidence limits on Se and Sp estimates fairly large.

There is much to be learned from the study details, including the supplementary information. Check out Fig.1 to see from where MAP was most often isolated. Read this well-written article, it is worth your time.

Link to the Journal of Veterinary Diagnostic Investigation


Bar


Bar
Friday, November 2, 2018
Killing MAP with Copper Ions Research Article

From the laboratory of Dr. Miguel Salgado, Associate Professor, Instituto de Medicina Preventiva Veterinaria, Facultad de Ciencias Veterinarias, Universidad Austral de Chile comes a novel study on killing MAP suspended in fluids using copper ions. As noted in this research article, the U.S. Environmental Protection Agency (EPA) approved the use of copper as an antimicrobial in 2008. The lead author, Pamela Steur, is a graduate student in Dr. Salgado’s laboratory and this is part of her PhD thesis work.

Comment: Multiple modes of testing MAP viability were used in this trial making the findings very convincing. However, this is a proof of concept article. It remains to be determined if the system will work in fluids such as milk. It is no coincidence that copper should be studied in Chile as it is the top producer of copper in the world, producing 5,750,000 tons of copper annually.

Disclosure: The author of this website is a coauthor on this publication.

Link to the full Open Access article.


Bar

Complete Listing

 

Back to Top

Line

If you have trouble accessing this site, please contact johnes@vetmed.wisc.edu.

SVM logo

 


Line

Copyright
Line
Contact
Line
Sponsorship
Line
Credits