Crohn’s disease is an inflammatory bowel disease, the general name for diseases that cause swelling in the intestines. Because the symptoms of Crohn’s disease are similar to other intestinal disorders, such as irritable bowel syndrome and ulcerative colitis, it can be difficult to diagnose. Ulcerative colitis causes inflammation and ulcers in the top layer of the lining of the large intestine. In Crohn’s disease, all layers of the intestine may be involved, and normal healthy bowel can be found between sections of diseased bowel.
Crohn’s disease affects men and women equally. About 20 percent of people with Crohn’s disease have a blood relative with some form of inflammatory bowel disease, most often a brother or sister and sometimes a parent or child. Crohn’s disease can occur in people of all age groups, but it is more often diagnosed in people between the ages of 20 and 30. People of Jewish heritage have an increased risk of developing Crohn’s disease, and African Americans are at decreased risk for developing Crohn’s disease.
Crohn’s disease may also be called ileitis or enteritis.
Wikipedia article on the disease gives us a primary information as below.
Crohn's disease is a disease of the digestive system which may affect any part of the gastrointestinal tract from mouth to anus. As a result, the symptoms of Crohn's disease can vary significantly among afflicted individuals. The main gastrointestinal symptoms are abdominal pain, diarrhea (which may be visibly bloody), vomiting, or weight loss. Crohn's disease can also cause complications outside of the gastrointestinal tract such as skin rashes, arthritis, and inflammation of the eye.
The precise cause of Crohn's disease is not known. The disease occurs when the immune system attacks the gastrointestinal tract and for this reason, Crohn's disease is considered an autoimmune disease. This autoimmune activity produces inflammation in the gastrointestinal tract, and therefore Crohn's disease is classified as an inflammatory bowel disease.
Like many other autoimmune diseases, Crohn's disease is believed to be genetically linked. The highest risk occurs in individuals with siblings who have the disease. Males and females are equally affected. Smokers are three times more likely to develop Crohn's disease. Crohn disease affects between 400,000 and 600,000 people in North America. Prevalence estimates for Northern Europe have ranged from 27–48 per 100,000. Crohn disease tends to present initially in the teens and twenties, with another peak incidence in the fifties to seventies, although the disease can occur at any age.
Unlike the other major types of inflammatory bowel disease, there is no known drug based or surgical cure for Crohn's disease. Treatment options are restricted to controlling symptoms, putting and keeping the disease in remission and preventing relapse.
The disease was independently described in 1904 by Polish surgeon Antoni Leśniowski and in 1932 by American gastroenterologist Burrill Bernard Crohn, for whom the disease was named. Crohn, along with two colleagues, described a series of patients with inflammation of the terminal ileum, the area most commonly affected by the illness. For this reason, the disease has also been called regional ileitis or regional enteritis.
