Technical Abstract: Johne's disease is a chronic, debilitating intestinal disorder in cattle, sheep and wild ruminants, characterized by diarrhea, weight loss and death. Animals usually become infected when they are young by ingesting feces or milk containing the causative bacteria. However, clinical signs of disease do not usually present themselves until the animals reach 3 to 5 years of age or even older. During this time the animal is infected and may be shedding the organism in its feces without showing any clinical signs of disease. In addition to reduced production by these animals, they also present a potential infective threat to the rest of the herd. Johne’s disease is difficult to diagnose and therefore to control. Diagnosis of infection is most frequently performed by direct culture or PCR of Mycobacterium avium subsp. paratubercuosis from the feces or by indirect measurement of antibodies in the serum and milk. Control measures for neonates to contaminated manure or milk. Vaccination is another management tool that is becoming more widely used. Mycobacterium avium subsp. paratuberculosis has been detected in tissues from some patients with Crohn’s disease, an inflammatory bowel disorder in humans. However, this association is not clear and Mb. a. paratuberculosis is not classified as a zoonotic agent.