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


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Use this section of the
site for a Johne's disease
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Table Bottom

Enlarged mesenteric lymph nodes
Johne’s disease frequently causes lymph nodes near the intestine to become enlarged (arrow).
Acid_fast stain: ileum
Special stains, called acid-fast stains, can reveal the red, rod-shaped mycobacteria in the intestinal tissue. They are clustered inside white blood cells.
AGID blood test for Johne’s disease
AGID test, sold under the trade name Rapid Johne’s Test, is a simple, easy to perform test for Johne’s disease that can be used on cattle with clinical signs; diarrhea and weight loss.
Scanning electron micrograph of M. paratuberculosis
M. paratuberculosis magnified over 50,000 times as seen by an electron microscope.
Giant cell in ileum
Giant cells in a acid-fast stained tissue section. Seeing such cells, along with acid-fast bacteria is diagnostic for paratuberculosis.
Histopathology: ileum
A thin section of bovine intestine stained with H&E, among the most common stains. The normal architecture of the tissue is changed due to inflammation in response to the M. paratuberculosis infection.
Standard culture method
Herrold’s egg yolk agar is a culture medium widely used to grow M. paratuberculosis from clinical samples like feces. Growth of bacterial colonies on this medium containing mycobactin, and not on medium without mycobactin (right hand tube), is indicative of M. paratuberculosis.
Heinrich Albert Johne
In 1895, this German physician, and his American colleague, Frothingham, were the first to describe the disease now known as bovine paratuberculosis.
Thickened intestinal mucosa due to Johne's disease
In cattle, infection of the intestine with M. paratuberculosis leads, over the course of several years, to marked thickening. This photos shows a normal (bottom) and affected bovine ileum.

Colonies of M. paratuberculosis
The colonial morphology of M. paratuberculosis is affected by the composition of the culture medium. This close up view of M. paratuberculosis colonies on Middlebrook agar medium shows the very rough colonial morphology typical of the organism grown in the absence of Tween.