Paratuberculosis is an infection caused by Mycohacterium paratuherculosis. Clinical paratuberculosis is known as Johne's disease. Most animals acquire the infection shortly after birth, but signs of illness usually are not apparent for several years.Paratuberculosis usually is spread from herd to herd by the purchase of infected animals that are not showing signs of the disease. We have found that cattle may shed the organisms in their feces for up to three years before exhibiting signs of the illness.