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Animal and Plant Health Inspection Service
U.S. Department of Agriculture
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Johne's Disease

Johne's disease (pronounced "yo-knees") is a contagious, chronic and usually fatal infection that affects primarily the small intestine of ruminants. All ruminants are susceptible to Johne's disease. Johne's disease is caused by Mycobacterium avium subspecies paratuberculosis, a hardy bacteria related to the agents of leprosy and tuberculosis. The disease is worldwide in distribution.

A national study of US dairies, Dairy NAHMS 96, found that approximately 22 percent of US dairy farms have at least 10% of the herd infected with Johne's disease. The study determined that infected herds experience an average loss of $40 per cow in herds with a low Johne's disease clinical cull rate while herds with a high Johne's disease clinical cull rate lost on average of $227. This loss was due to reduced milk production, early culling, and poor conditioning at culling. The cost of Johne's disease in beef herds still need to be determined.

Signs of Johne's disease include weight loss and diarrhea with a normal appetite. Several weeks after the onset of diarrhea, a soft swelling may occur under the jaw (bottle jaw). Bottle jaw or intermandibular edema is due to protein loss from the bloodstream into the digestive tract. Animals at this stage of the disease will not live very long, perhaps a few weeks at most.

Signs are rarely evident in cattle until two or more years after the initial infection, which usually occurs shortly after birth. Animals are most susceptible to the infection in the first year of life. Newborns most often become infected by swallowing small amounts of infected manure from the birthing environment or udder of the mother. In addition, newborns may become infected while in the uterus or by swallowing bacteria passed in milk and colostrum. Animals exposed at an older age, or exposed to a very small dose of bacteria at a young age, are not likely to develop clinical disease until they are much older than two years.

Farm specific plans can be implemented to reduce economic losses and cleanup Johne's disease from the farm. For more information on Johne's disease, diagnosis, prevention, and control, contact your herd veterinarian or your State's extension office.  Work with your veterinarian to develop a strategic plan for Johne's prevention and control for your farm.

Some basic prevention strategies are:

  • Calves, lambs, kids, etc. should be born in a clean environment.
  • Reduce the newborns exposure to manure from adult animals by separation when possible.
  • Avoid manure contamination of feed by using feed bunks and not using the same equipment to handle feed and move manure.
  • Avoid manure contamination of water sources were animals drink.
  • For natural colostrum needs of newborn animals, use colostrum from Johne's negative animals.
  • Do not pool colostrum.
  • Avoid natural nursing and milk feeding whenever possible. Feed an artificial milk replacer or pasteurized milk instead of raw milk to supply the needs of newborns. Never feed pooled milk or waste milk.
  • Thoroughly clean the udder and teats before collection of the colostrum to avoid manure contamination.
  • MAP can survive up to a year in the environment so if possible, for pastures that have become contaminated, till the ground or graze using non replacement feeder cattle.
  • Identify all females in the herd. Identify and remove, or keep separate all test positive animals.
  • Prevent infection from spreading by culling, or separating offspring of infected mothers as soon as possible.
  • If purchasing herd additions, try to buy from low risk herds. Some herds are enrolled in the Voluntary Bovine Johne's Disease Control Program to help identify their herd as low risk.

Consult with your veterinarian about which Johne's test is best for your situation and use an APHIS approved diagnostic laboratory.

Click here for a list of laboratories which have passed the Johne's serology and/or organism detection check testing.

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