A slowly progressive diarrheal disease that causes major economic loss to the cattle industry; also known as paratuberculosis. It is caused by Mycobacterium avium ss paratuberculosis (MAP), which produces chronic inflammation of the mucosa of the ileocecal valve and adjacent tissues of the gastrointestinal tract of cattle, sheep, goats, and wild ruminants. The organism has been isolated from 2–3% of the adult cows in the United States; in some exotic species (such as mouflon and mountain goats), more than 90% of the animals in a herd may be infected. Animals less than 2 months of age are most susceptible to infection. Therefore, eliminating or minimising exposure of young animals to MAP is important in the control of Johne's disease. It is recommended that calves be removed from dams immediately after birth and fed colostrum from negative animals.