This interested me because of the observation re: using cattle in a
decontamination program for sheep. TTMI.
JOHNES DISEASE, SHEEP - AUSTRALIA
A ProMED-mail post
Date: Wed, 21 Jul 1999 01:11:22 -0400
From: "Marjorie P. Pollack"
Source: Australia Broadcasting Network: Tuesday 20 July, 1999 (1:41pm AEST)
Tests Confirm Cattle Strain of Johnes Disease in Sheep
Strain testing of South Australia's only confirmed mainland case of Johnes
Disease in sheep has revealed the mid north property carries not Ovine - but
Bovine Johnes Disease.
The Woolana Stud at Mount Bryan has become the third property in the country
to confirm sheep with the cattle strain of Johnes.
Greg Johnson from the Kangaroo Island Ovine Johnes Action group, says strain
testing of sheep under the Johnes Market Assurance program should become
If sheep can catch Bovine Johnes disease, destocking and replacing them with
cattle may not be the best course of action.
Greg Johnson said, "Using cattle for any sort of a decontamination program
in destock properties might be a difficult thing to do because it's
possible the contamination of the pasture with cattle strains of Johnes
disease could result in disease and further contamination in those cattle
during the supposed decontamination period. The other issue is it means the
whole definition and the way that Johnes disease is viewed in the country
needs to be seriously examined and changed."
[Although previous titles on ProMED-mail have read "Ovine-Johnes," I think
the correct term should be "Johnes Disease, Sheep," or "Johnes Disease,
Ovine." Johnes is NOT just a bovine disease.
Johnes Disease is caused by _Mycobacterium avium paratuberculosis_, formerly
known as _M paratuberculosis_. Paratuberculosis is a chronic, contagious
enteritis, characterized by progressive, and persistent diarrhea,
debilitation, weight loss, and eventually death. It affects, cattle, sheep,
goats, llamas, camels, farmed deer, and other domestic, exotic and wild
ruminants. It has ben recognized in wild rabbits, too. Horses and pigs have
been infected experimentally, only. The distribution of this disease is
Crohn¥s disease is a chronic enteritis in man. There is conflicting data on
the involvement of the causative organism in Crohn¥s disease. Therefore,
animals with paratuberculosis should be considered as potential zoonotic
risks until the situation with Crohn¥s disease is clarified.
Johnes Disease is characterized by weight loss and diarrhea, but initially
the signs are vague and variable. Diarrhea may be intermittent, is typically
thick, does not contain blood or mucus. The diarrhea becomes more severe
over weeks or months and there is further weight loss. Dairy animals have a
drop in milk production. The disease is progressive and terminates in
emaciation and death.
There is not single, good diagnostic test. A combination of tests is often
used. Diagnosis is easier on a group of animals than a single animal. Fecal
culture is specific, but not highly sensitive because the organisms are shed
intermittently. Serological tests vary in sensitivity and specificity and
are poor at identifying sub clinical cases.
There is no known treatment for paratuberculosis. Control requires good
sanitation and management. There is a vaccine used in some countries, and
subject to approval by regulatory agencies and restricted to infected herds.
Vaccines and diagnostic tests are limited in efficacy. Calfhood (less than 1
month of age) vaccination can be effective in reducing disease incidence but
does not eliminate the infection.
Cattle inoculated with the inactivated, whole-cell, mineral-oil vaccine
develop granulomas, up to several cm in diameter, at the site of
inoculation, which is usually the brisket. These vaccines may cause the
cattle to react positively on subsequent tuberculin test. Accidental
self-inoculation can result in severe acute reactions with sloughing and
chronic synovitis and tendinitis. Vaccination does not eliminate the need
for good sanitation and management - Mod.TG]
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