Crohn's disease is a type of inflammatory bowel disease (IBD) that may affect any segment of the gastrointestinal tract. Symptoms often include abdominal pain, diarrhea, fever, abdominal distension, and weight loss. Complications outside of the gastrointestinal tract may include anemia, skin rashes, arthritis, inflammation of the eye, and fatigue. The skin rashes may be due to infections as well as pyoderma gangrenosum or erythema nodosum. Bowel obstruction may occur as a complication of chronic inflammation, and those with the disease are at greater risk of colon cancer and small bowel cancer. Although the precise causes of Crohn's disease (CD) are unknown, it is believed to be caused by a combination of environmental, immune, and bacterial factors in genetically susceptible individuals. It results in a chronic inflammatory disorder, in which the body's immune system defends the gastrointestinal tract, possibly targeting microbial antigens. While Crohn's is an immune-related disease, it does not seem to be an autoimmune disease (the immune system is not triggered by the body itself). The exact underlying immune problem is not clear; however, it may be an immunodeficiency state. About half of the overall risk is related to genetics, with more than 70 genes involved. Tobacco smokers are three times as likely to develop Crohn's disease as non-smokers. It often begins after gastroenteritis. Other conditions with similar symptoms include irritable bowel syndrome and Beh?et's disease. There is no known cure for Crohn's disease. Treatment options are intended to help with symptoms, maintain remission, and prevent relapse. In those newly diagnosed, a corticosteroid may be used for a brief period of time to improve symptoms rapidly, alongside another medication such as either methotrexate or a thiopurine used to prevent recurrence. Cessation of smoking is recommended for people with Crohn's disease. One in five people with the disease is admitted to the hospital each year, and half of those with the disease will require surgery at some time during a ten-year period. While surgery should be used as little as possible, it is necessary to address some abscesses, certain bowel obstructions, and cancers. Checking for bowel cancer via colonoscopy is recommended every few years, starting eight years after the disease has begun. Crohn's disease affects about 3.2 per 1,000 people in Europe and North America; it is less common in Asia and Africa. It has historically been more common in the developed world. Rates have, however, been increasing, particularly in the developing world, since the 1970s. Inflammatory bowel disease resulted in 47,400 deaths in 2015, and those with Crohn's disease have a slightly reduced life expectancy. It tends to start in adolescence and young adulthood, though it can occur at any age. Males and females are equally affected.

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Wiki: Crohn's disease