What causes the signs of Johnes disease?
M. paratuberculosis infects the part of the small intestine called the ileum. There it causes a certain type of inflammation called granulomatous inflammation. This inflammation thickens the intestinal wall, preventing it from functioning normally. This leads to diarrhea and poor absorption of nutrients. As a result, even though infected animals seem to be feeling and eating well, they will rapidly lose weight.
