Causes of watery diarrhea
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Infectious Causes of Watery Diarrhea
Acute watery diarrhea is most commonly caused by infections, especially in children. Rotavirus is a leading cause of severe acute watery diarrhea in children worldwide, even after the introduction of rotavirus vaccines, and is responsible for a significant proportion of cases in both developed and developing countries Operario2017Iyoha2015. Other infectious agents include certain types of Escherichia coli. Enterotoxigenic E. coli (ETEC) is a major cause of watery diarrhea, particularly in children and travelers, due to its production of enterotoxins that disrupt normal water absorption in the intestines . Enteroaggregative E. coli (EAEC) is also recognized as an important cause of persistent and sometimes inflammatory watery diarrhea in both children and adults .
Non-Infectious and Chronic Causes of Watery Diarrhea
Chronic watery diarrhea, defined as diarrhea lasting more than four weeks, often has non-infectious causes. Bile acid malabsorption, sugar malabsorption (such as lactose or fructose intolerance), and gluten-sensitive enteropathy (celiac disease) are significant contributors to chronic watery diarrhea. In a study of patients with chronic watery diarrhea, bile acid malabsorption was the most common cause, followed by sugar malabsorption and gluten-sensitive enteropathy. Only a minority of cases were classified as functional (without an identifiable organic cause) after thorough testing .
Microscopic Colitis as a Cause of Chronic Watery Diarrhea
Microscopic colitis is a relatively common cause of chronic watery diarrhea, especially in older adults. It is characterized by inflammation of the colon that is only visible under a microscope, as the colon appears normal during endoscopy. There are two main types: collagenous colitis and lymphocytic colitis. Both types present with similar symptoms, including watery diarrhea, abdominal pain, and sometimes weight loss. Diagnosis requires a colon biopsy, and treatment often leads to symptom improvement Kingham1982Pardi2011Pardi2002+1 MORE.
Pathophysiological Mechanisms of Watery Diarrhea
Watery diarrhea can result from several mechanisms: decreased absorption of solutes in the intestines, increased secretion of water and electrolytes, or a combination of both. Disruption of the intestinal barrier or abnormal activation of secretory pathways can also contribute. These mechanisms are relevant in both infectious and non-infectious causes of diarrhea .
Conclusion
Watery diarrhea can be caused by a range of infectious agents, with rotavirus and certain E. coli strains being most common in acute cases, especially in children. Chronic watery diarrhea is often due to bile acid malabsorption, sugar malabsorption, gluten-sensitive enteropathy, or microscopic colitis. Accurate diagnosis is important, as many cases previously thought to be functional have an identifiable organic cause. Understanding the underlying mechanism is key to effective management and treatment.
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