Control of Johne's disease
- Johne's disease can be controlled and even eliminated from infected herds or flocks, however, it
takes a thorough understanding of the disease by animal owners, consultation with a veterinarian,
and requires use of one or more of the available diagnostic tests. Halfhearted attempts to control
Johne's disease will generally fail. Control of Johne's disease also takes time. A typical herd clean
up program may take 5 years or longer. Faster clean up programs are possible, but they are usually
more expensive. The basics of control are simple: new infections must be prevented, and animals
with the infection must be identified and removed from the herd or flock. A computer simulation
model illustrates how Johne's control takes time and how faster Johne's control can be
accomplished by both changing animal management procedures and by testing the herd of flock and
culling the test-positive animals. This web page will describe in more detail how to implement these
two basic techniques for Johne's disease control.
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- . . . manure management
- The largest number of M. paratuberculosis bacteria excreted by infected animals are in the feces
(manure). Farm sanitation and control over where manure goes on a farm are critical to control of
Johne's disease. Because of the susceptibility of young animals to M. paratuberculosis infection,
it is important to keep them well away from feces of adult animals that may harbor the infection. The
longer separation of young stock and adults can be maintained the better. For dairy cattle the
minimum time for complete separation is the first 6 months of life, the "window" of maximum
susceptibility.
- Animals should be born in a clean dry environment with minimal fecal contamination. For dairy
cattle, prompt removal of the newborn from its mother is recommended for control of Johne's
disease, as well as several other dairy cattle diseases. This practice is not practical for many other
animal species although in certain circumstances should be considered. For example, in small herds
of pygmy goats, hand rearing of newborns by bottle feeding and housing young animals in a facility
separate from the adults may be essential to avoid new M. paratuberculosis infections.
- Manure contamination of feed by use of dirty feeding equipment should be avoided. Also, manure
contamination of water supplies, particularly ponds or streams that animals can drink from, must be
avoided to limit spread of the infection.
- Pasture contamination with M. paratuberculosis is theoretically important as a means of infection
transmission, but is less likely than other modes of transmission and far more difficult to control. If
possible, infected pastures should be tilled, otherwise waiting for environmental conditions to cause
destruction of M. paratuberculosis on pastures must be depended on. This can take up to a year.
- . . . milk management
- Many animals infected with M. paratuberculosis will excrete the bacterium in their milk. This is true
of cattle as well as smaller ruminants like sheep and goats. M. paratuberculosis excretion in milk
happens most often in animals with clinical signs of Johne's disease, but occurs in infected animals
that appear healthy too. Because no diagnostic test can detect all infected animals, to control
Johne's disease it is best if feeding of raw milk and natural nursing can be avoided. This is easier
for dairy cattle than for most other species of animals, but always should be considered. Artificial
milk replacers are considered free of M. paratuberculosis.
- Colostrum, the antibody-rich milk produced by mothers the first few days after giving birth, can
contain M. paratuberculosis. Because colostrum is critical to the health and survival of newborns,
feeding of colostrum must be done. However, the risk of transmitting M. paratuberculosis infections
in colostrum can be minimized by:
- only using colostrum from Johne's test-negative animals
- not pooling colostrum from multiple animals
- thoroughly cleaning the udder and teats before collection of colostrum to avoid manure contamination.
- . . . culling offspring of infected mothers
- M. paratuberculosis infections can be transmitted from mothers to offspring by contact with the
mother's infected feces, through infected colostrum or milk from the mother, or across the placenta
into the fetus before the baby is born. Depending on the extent to which manure management and
milk/colostrum management recommendations listed above can be implemented, there is a
moderate to high probability that offspring born to M. paratuberculosis-infected mothers will acquire
the infection. Consequently, on a case by case basis, it may be wise to cull offspring born to
infected mothers. If not culled, it may take two or more years to determine if the young animal
became infected, and this will be time lost in pursuit of control or eradication of the M.
paratuberculosis in the herd or flock.
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Identify and remove infected animals: test-and-cull program
- The majority of M. paratuberculosis infections in a herd or flock are "invisible". Animals with clinical signs of Johne's disease, diarrhea and weight loss, are only a small fraction of the truly infected animals. The infection has the ability to silently spread from animal to animal long before signs of illness in infected animals are evident. For this reason, laboratory tests are important to determine
which animals are infected. Test-positive animals are generally those most likely to be infectious
(excreting M. paratuberculosis) and so they should be removed, or at least isolated from, the herd or flock.
- Referred to as a test-and-cull program, this practice is essential to successful control of Johne's
disease in herds or flocks in a reasonable period of time. Clearly, there are situations where
alternatives must be considered: testing and culling of all test-positive animals is not necessarily
always required. With the great diversity of animal species affected by Johne's disease and the
differences in husbandry practices and economic value of these different species, it is difficult to
generalize about test-and-cull recommendations. Decisions on how best to implement testing in a
Johne's control program should be made in consultation with a veterinarian. For details about
available laboratory tests for Johne's disease, see the d at this web site.
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- M. paratuberculosis is resistant to most commonly used disinfectants. Destruction of M.
paratuberculosis on surfaces that might be contaminated requires thorough cleaning with soap and
water followed by application of a disinfectant that is "tuberculocidal". Tuberculocidal disinfectants
usually contain strong chemical compounds and should be used carefully. Label instructions for
proper use and safe handling should be followed precisely.
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- Collins, M.T. 1994. Clinical approach to control of bovine paratuberculosis. J.Am.Vet.Med.Assoc.
204:208-210.
- Collins, M.T. and I. R. Morgan. 1991. Economic decision analysis model of a paratuberculosis test
and cull program. J.Am.Vet.Med.Assoc. 199:1724-1729.
- Collins, M.T. and I. R. Morgan. 1992. Simulation model of paratuberculosis control in a dairy herd.
Prev.Vet.Med. 14:21-32.
- Gay, J.M. and D. M. Sherman. 1992. Factors in the epidemiology and control of ruminant
paratuberculosis. Vet.Med. 87:1133-1139.
- McCaughan, C.J. 1989. On-farm management of Johne's disease, p.53-60. In A.R. Milner and
P.R. Wood (ed.), Johne's disease. Current trends in research, diagnosis and management, CSIRO,
Melbourne.
- Sherman, D.M. 1985. Current concepts in Johne's disease. Vet.Med. 80:77-84.
- van der Giessen, J.W.B., R. M. Haring, E. Vauclare, A. Eger, J. Haagsma, and B. A. M. van der
Zeijst. 1992. Evaluation of the abilities of three diagnostic tests based on the polymerase chain
reaction to detect Mycobacterium paratuberculosis in cattle: Application in a control program.
J.Clin.Microbiol. 30:1216-1219.
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Last revised February 19, 1997.
URL is http://www.vetmed.wisc.edu/pbs/johnes/control.html.html.
Web Designer can be contacted at: mcdonal7@facstaff.wisc.edu
All material Copyright © 1996 by the Board of Regents of the University of Wisconsin System. School of Veterinary Medicine, all rights reserved. If you have questions or comments about this page email us at: mcollin5@facstaff.wisc.edu