Gastroenteritis is a nonspecific term for various pathologic states of the gastrointestinal tract. The primary manifestation is diarrhea, but it may be accompanied by nausea, vomiting, and abdominal pain. A universal definition of diarrhea does not exist, although patients seem to have no difficulty defining their own situation. Although most definitions center on the frequency, consistency, and water content of stools, the author prefers defining diarrhea as stools that take the shape of their container.
The severity of illness may vary from mild and inconvenient to severe and life threatening. Appropriate management requires extensive history and assessment and appropriate, general supportive treatment that is often etiology specific. Diarrhea associated with nausea and vomiting is referred to as gastroenteritis.
Diarrhea is one of the most common reasons patients seek medical care. In the developed world, it is one of the most common reasons for missing work, while in the developing world, it is a leading cause of death. In developing countries, diarrhea is a seasonal scourge usually worsened by natural phenomena, as evidenced by monsoon floods in Bangladesh in 1998 or the earthquake in Haiti in 2010. An estimated 179 million cases of acute gastroenteritis occur every year in the United States.  Of these patients, 80-85% do not seek medical attention, and only 1-2% require hospital admission. Diarrheal diseases can quickly reach epidemic proportions, rapidly overwhelming public health systems in even the most advanced societies.