Snapshot A 3-year-old boy with no significant past medical history is brought to urgent care for 2 days of watery diarrhea. He had been attending daycare 2 times a week, and several other kids have also experienced similar symptoms. He has had 5-6 bowel movements per day and has not been able to eat much. His parents have been encouraging him to drink oral electrolyte solution. On physical exam, he is noted to have sunken eyes, poor skin turgor, and increased capillary refill time. Introduction Overview acute diarrhea is characterized by acute onset of > 3 bowel movements/day lasting < 14 days and is often caused by infection persistent diarrhea lasts 2-4 weeks chronic diarrhea lasts > 4 weeks and is often caused by underlying conditions such as inflammatory bowel disease or fat malabsorption Epidemiology Incidence very common rotavirus is most common cause of infectious diarrhea worldwide vaccine available acute diarrhea is the second cause of childhood mortality in the world Demographics viral diarrhea is most common in children especially rotavirus and adenovirus Etiology Infections viruses bacteria parasites Drug-induced quinidine colchicine cytotoxic agents chemotherapy Food allergies Toxic ingestions Autoimmune Small intestine bacterial overgrowth, often secondary to scleroderma or diabetes Pathogenesis types of diarrhea exudative/inflammatory diarrhea frequent, small-volume, bloody stools indicates disrupted and inflamed mucosa etiologies infectious (i.e., Shigella, Salmonella, E. coli, Campylobacter, and amebiasis) idiopathic inflammatory bowel disease (ulcerative colitis and Crohn disease) ischemic colitis fatty diarrhea weight loss and greasy or bulky stools that float that are often chronic etiologies fat malabsorption watery diarrhea osmotic diarrhea due to osmotic pull of water into the intestinal lumen etiologies giardiasis laxatives lactose intolerance secretory diarrhea due to active secretion of water etiologies infectious (i.e., enterotoxic E. coli and Vibrio) carcinoid syndrome gastrinoma drugs (i.e., colchicine) Infectious Bloody Vs Watery Diarrhea Bloody Diarrhea Watery Diarrhea Campylobacter E. histolytica Enterohemorrhagic E. coli Enteroinvasive E. coli Non-thypoidal Salmonella Shigella Y. enterocolitica C. difficile C. perfringens Enterotoxigenic E. coli Giardia Cryptosporidium V. cholerae Rotavirus Norovirus Adenovirus S. aureus High Yield Risk Factors Exposure Risk Factors Associated Organisms Daycare Rotavirus, astrovirus, calicivirus, Campylobacter, Shigella, Giardia, Cryptosporidium Food Dairy Eggs Beef Poultry Pork Seafood Oysters Rice/Pasta Campylobacter and Salmonella Salmonella E. coli Campylobacter C. perfringens Y. enterocolitica Astrovirus Vibrio Calicivirus Bacillus cereus Water exposure Swimming Pools Contaminated water with cysts Shigella Giardia, E. histolytica, and Cryptosporidium Travel history "Traveler's" diarrhea Cruise ships Camping/hiking E. coli, Giardia, Salmonella, Shigella, and Campylobacter Norovirus Giardia Past medical history Antibiotics/hospitalization C. difficile and rotavirus Pets Dog feces Turtles/reptiles Other animals/pets Yersinia enterocolitica Non-typhoidal Salmonella Campylobacter Presentation Symptoms common symptoms dehydration lethargy feeling of thirst diarrhea foul-smelling along with stools that float bloody diarrhea watery diarrhea other enteric symptoms nausea vomiting abdominal pain/cramping Physical exam inspection dry mucous membranes sunken eyes poor skin turgor delayed capillary refill Studies Acute diarrhea does not routinely require laboratory evaluation, unless clinical presentation includes high fever bloody diarrhea severe abdominal pain requires hospitalization elderly immunocompromised status Serum labs complete blood count Stool studies ova and parasite examination C. difficile toxin leukocyte presence suggests enteroinvasive infection pH < 5.5 usually indicates viral illness and can also indicate lactase deficiency culture enzyme immunoassay for rotavirus and adenovirus antigens latex agglutination assay for rotavirus Differential Chronic diarrhea, which lasts 4 weeks or more, suggests other etiologies, such as fat malabsorption syndrome Radiation injury high doses of radiation classically cause diarrhea and lymphopenia (poor prognosis) Chronic DiarrheaMalabsorption syndromesCeliac diseaseLactose intolerancePancreatic insufficiencyDiabetic neuropathyInflammatory bowel diseaseCrohn diseaseUlcerative colitisOther gastrointestinal causesMicroscopic colitisIrritable bowel syndromeEndocrinologicalCarcinoidGastrinomaDrug-inducedQuinidineColchicineChemotherapyOtherSevere combined immunodeficiencyArsenic poisoningVitamin C toxicityVitamin B3 deficiency Treatment Medical supportive care modalities oral rehydration (preferred) no need for advanced studies in healthy, well-appearing individuals intravenous rehydration electrolyte repletion antibiotics indication for bacterial etiologies causing moderate or severe diarrhea and not responsive to rehydration metronidazole or tinidazole for Giardia infections doxycycline for V. cholerae oral vancomycin for C. difficile infection anti-motility agents indication may prolong certain infectious diarrhea, such as Shigella-induced gastroenteritis acute diarrhea modalities loperamide bismuth salicylate Complications Dehydration