The major causes and the prevalence of chronic diarrhea differ between developed and developing countries. In the developing world, chronic diarrhea is typically associated with serial enteric infections and malnutrition; it is manifested by a chronic enteropathy, with impaired mucosal healing and diminished digestive and absorptive capacity .
In developed countries, children are less likely to be exposed to serial enteric infections and malnutrition. In these populations, chronic diarrhea is more likely to be induced by underlying disease causing malabsorption or maldigestion [2-5]. However, enteric infections (particularly in immunocompromised patients), malnutrition, and dietary factors (eg, excessive consumption of juice), play a role in some cases.
The difference in pathophysiology underlying most cases of chronic diarrhea in developing countries as compared to those in developed countries calls for different approaches to diagnosis and management in the two settings. The diagnosis and treatment of chronic diarrhea in developing countries is discussed separately. (See "Persistent diarrhea in children in developing countries".)
The pathophysiology and management of diarrheal diseases in developed countries will be reviewed here. The approach to diagnosing the cause of these diarrheal diseases is discussed separately. (See "Approach to the diagnosis of chronic diarrhea in children in developed countries".)
Chronic diarrhea is defined as stool volume of more than 10 grams/kg/day in infants and toddlers, or more than 200 grams/day in older children for more than 14 days . This typically translates to persistent loose or watery stools occurring at least three times a day, where the change in stool consistency is more important than stool frequency . Some authors make a distinction between chronic diarrhea, which they define as having a gradual onset, from persistent diarrhea, which they define as having a sudden onset. However, it is frequently difficult to identify the time of onset of the diarrhea and delineation of the two entities can be problematic. Consequently, for the purposes of this review we will not differentiate between persistent and chronic diarrhea.