Animation of an endoscope view of the intestine affected by Crohn's disease. This is a severe inflammatory bowel disease that causes ulceration and inflammation of the intestinal walls, and a range of other symptoms. It is thought to be caused by a combination of genetic and environmental factors, leading to disruption of the immune system and its subsequent attack on intestinal tissues. Crohn's disease causes pain, diarrhoea, vomiting and weight loss. There is no definitive treatment for the condition, with control and management the only options.