Precision Diagnostics LLC
Specializing in reproductive management
Precision diagnostics is now offering a Johne’s disease ELISA test at a cost of $6.00 per sample.
Johne’s disease is caused by a bacterium called Mycobacterium avium sp. Paratuberculosis (or
MAP). This bacterium colonizes cells in the intestines of cattle and other ruminants and causes
thickening of the intestinal wall which prevents the animal from absorbing nutrients. Infected
animals shed MAP bacteria in their manure; highly infected cows may shed MAP in milk and
colostrum as well. The bacteria can survive in manure or stagnant water for 1 year or more and
can even survive the ensiling process! Cattle acquire Johne’s by ingestion of manure from an
infected animal; often occuring when water or feed are contaminated with manure.
The symptoms of Johne’s disease include diarrhea and poor body condition despite having a
good appetite. Cattle with Johne’s disease also experience decreased milk production and
reproductive performance. Once symptoms begin, the animal will not recover and will
continue to deteriorate. Johne’s disease is unique in that, although most infections occur
before 6 months of age, animals will not show symptoms before they are 2-3 years old. This
means that an animal can be infected and shed bacteria which infect healthy animals with no
outward signs. It is estimated that for every clinical (symptomatic) case of Johne’s there are 1525 subclinical (no symptoms) cases in the herd.
Since there are no available treatment options, the best defense against Johne’s disease is
prevention. If you are buying animals be sure to purchase from a herd certified free of Johne’s
disease. Even if you do not suspect Johne’s in your herd it is always good practice to prevent
contamination of feed and water with manure by always using separate equipment for handling
each. Since most Johne’s infections are acquired before 6 months of age it is essential to
reduce exposure of calves to manure from adult animals. This is especially important in herds
with confirmed Johne’s cases.
Because of the economic significance and prevalence of Johne’s disease, as well as the delayed
onset of symptoms, implementing a testing program is an excellent way to detect and reduce
Johne’s cases in your herd. The Johne’s test offered by Precision Diagnostics works by detecting
antibodies produced by the cow’s immune system in response to MAP bacteria. The test
correctly identifies positive animals 68% of the time and correctly identifies negative animals
99% of the time. A unique feature of the test is that it provides a specific value associated with
the amount of antibody present in the cow. This feature allows us to determine if an animal is
negative, strongly positive, weakly positive, or “suspect.” Knowing these categories can help
producers make decisions such as whether or not to cull, keep, separate, or re-test an animal.
An added bonus is that the Johne’s test can be performed on the same blood sample
submitted for the bioPRYN pregnancy test! A copy of our new submission form is on the back
of this newsletter. We plan to offer the test for goats soon in addition to the currently offered
test for cattle. Please call with any questions.
P.O. Box 344 East Earl, PA 17519
www.precisiond.com
717-354-2178