Also called regional enteritis or regional ileitis, this is a nonspecific inflammatory disease of the upper and lower intestine that forms granulated lesions. It is usually a chronic condition, with acute episodes of diarrhea, abdominal pain, loss of appetite, and loss of weight. It may affect the stomach or colon, but the most common sites are the duodenum and the lowest part of the small intestine, the lower ileum. The standard treatment is, initially, anti-inflammatory drugs, with surgical resectioning often necessary. The disease is autoimmune, and sufferers share the same tissue type (HLA-B27) as those who acquire ankylosing spondylitis.