Treatment of Mycobacterium paratuberculosis infection in ruminants.

Paratuberculosis is a chronic, debilitating, fatal condition that usually is clinically undetectable until the onset of copious diarrhea. Paratuberculosis is caused by an acid-fast organism, M. paratuberculosis. Successful eradication of paratuberculosis depends on the early detection of infected animals, thereby allowing removal of carrier animals from the herd. Treatment for paratuberculosis is therefore rarely indicated or undertaken; however, treatment may be considered for animals of exceptional genetic value or companion animals. Antimicrobials reviewed in this article for the treatment of paratuberculosis include isoniazid, rifampin, streptomycin, amikacin, clofazimine, and dapsone. Treatment of paratuberculosis requires daily medication for extended periods and results in palliation of the disease rather than a definitive cure. The treatment for paratuberculosis recommended by the authors is isoniazid at 20 mg/kg administered orally every 24 hours for the rest of the animal's life. When the animal has acute onset of diarrhea, rifampin at 20 mg/kg every 24 hours is also administered orally. In severe, imminently life-threatening cases, an aminoglycoside should be administered concurrently for 3 to 8 weeks. This protocol (isoniazid, rifampin, and an aminoglycoside) will help ensure that Mycobacteria organisms are sensitive to at least two of the antibiotics. Rifampin treatment can be discontinued if clinical signs of paratuberculosis disappear and the cost of therapy is judged excessive. The combined therapeutic approach has been used in three animals, and the results are presented in this article. Because isoniazid, rifampin, and some aminoglycosides are not approved for use in food animals in the United States of America, the meat or milk from treated animals should not be used for human consumption.