Crohn's disease is an inflammatory bowel disease in which inflammation injures the intestines. It is a long-term (chronic) condition. Crohn's disease typically begins between ages 15 and 40.
No one knows for sure what triggers the initial intestinal inflammation at the start of Crohn's disease. A viral or bacterial infection may start the process by activating the immune system. The body's immune system stays active and creates inflammation even after the infection goes away.
Certain genes passed on from parent to child may increase risk of developing Crohn's disease if the right trigger occurs.
Once Crohn's disease begins, it can cause lifelong symptoms that come and go. The inside lining and deeper layers of the intestine wall become inflamed. The lining of the intestine becomes irritated. It can thicken or wear away in spots. This creates ulcers, cracks and fissures. Inflammation can allow an abscess (a pocket of pus) to develop.
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