What Is It? 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. A common complication of Crohn's disease is called a
fistula. A f