Virus present in the human system

The most common cause is an infection of the intestines due to either a virus, bacteria, or parasite—a condition also known as gastroenteritis.^[2] These infections are often acquired from food or water that has been contaminated by feces, or directly from another person who is infected.^[2] The three types of diarrhea are: short duration watery diarrhea, short duration bloody diarrhea, and persistent diarrhea (lasting more than two weeks, which can be either watery or bloody).^[2] The short duration watery diarrhea may be due to cholera, although this is rare in the developed world.^[2] If blood is present, it is also known as dysentery.^[2] A number of non-infectious causes can result in diarrhea.^[5]These include lactose intolerance, irritable bowel syndrome, non-celiac gluten sensitivity, celiac disease, inflammatory bowel diseasesuch as ulcerative colitis, hyperthyroidism, bile acid diarrhea, and a number of medications.^[5][6][7] In most cases, stool cultures to confirm the exact cause are not required.^[8]

Diarrhea can be prevented by improved sanitation, clean drinking water, and hand washing with soap.^[2] Breastfeeding for at least six months and vaccination against rotavirus is also recommended.^[2] Oral rehydration solution (ORS)—clean water with modest amounts of salts and sugar—is the treatment of choice.^[2] Zinc tablets are also recommended.^[2] These treatments have been estimated to have saved 50 million children in the past 25 years.^[1] When people have diarrhea it is recommended that they continue to eat healthy food and babies continue to be breastfed.^[2] If commercial ORS are not available, homemade solutions may be used.^[9] In those with severe dehydration, intravenous fluids may be required.^[2] Most cases; however, can be managed well with fluids by mouth.^[10] Antibiotics, while rarely used, may be recommended in a few cases such as those who have bloody diarrhea and a high fever, those with severe diarrhea following travelling, and those who grow specific bacteria or parasites in their stool.^[8]Loperamide may help decrease the number of bowel movements but is not recommended in those with severe disease.^[8]

About 1.7 to 5 billion cases of diarrhea occur per year.^[2][5][11] It is most common in developing countries, where young children get diarrhea on average three times a year.^[2]Total deaths from diarrhea are estimated at 1.26 million in 2013—down from 2.58 million in 1990.^[12] In 2012, it was the second most common cause of deaths in children younger than five (0.76 million or 11%).^[2][13] Frequent episodes of diarrhea are also a common cause of malnutrition and the most common cause in those younger than five years of age.^[2] Other long term problems that can result include stunted growth and poor intellectual development.^[13