Pathophysiology of disease: Acute diarrhea is caused by a bacterial, viral or parasitic infection. Chronic diarrhea is usually related to a functional disorder such as irritable bowel syndrome or an intestinal disease such as Crohn's disease. The most common cause of diarrhea is infection of the intestines due to either virus, bacteria or parasite. This condition known as gastroenteritis. These infections are often acquired from food or water that has been contaminated by stool, or directly from another person who is infected. It may be divided into three types: short duration watery diarrhea, short duration bloody diarrhea, persistent diarrhea.