Inflammatory bowel disease (IBD) is a general term for a group of chronic inflammatory disorders of the intestines characterized by recurrent inflammation in specific parts of the intestines. The two main types of IBD are Crohn’s disease and ulcerative colitis.
In Crohn’s disease, the ileum (the final part of the small intestine) is the primary area affected, although the inflammatory reaction may also involve the mucosa of the mouth, esophagus, stomach, duodenum (the first part of the small intestine), jejunum (the middle portion of the small intestine), colon (the large intestine), the mesentery (outside covering of the intestines), or the lymph nodes in the abdominal region. In ulcerative colitis, the lining of the colon is the area affected.
IBD may occur at any age, but initial appearance is typically between the ages of 15 and 35 years, and women are affected slightly more often than men. Caucasians develop IBD two to five times more often than people of African or Asian descent, and individuals of Jewish descent have a three to six times higher incidence compared with other Caucasians. Ulcerative colitis is more common than Crohn’s disease, averaging between 70 and 150 cases per 100,000 people. The average incidence of Crohn’s disease is 20–40 cases per 100,000; however, the rate of Crohn’s disease is increasing in the West, possibly due to excessive antibiotic use and the Western diet.