Snapshot A 25-year-old man presents to his primary care physician for evaluation of diarrhea. He had recently gone to Mexico for spring break, where he stayed in a hostel with his friends. He spent a lot of time on the beach, swimming in caves, and hiking. He reports having onset of watery diarrhea about a week ago. He has not had any fevers, nausea, or vomiting. He does recall eating multiple rounds of raw oysters while in Mexico. He is found to be dehydrated, with poor skin turgor and dry mucous membrane. 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 autoimmun small intestine bacterial overgrowth, often secondary to scleroderma or diabetes Pathogenesis types of diarrhea exudative/inflammatory diarrhea frequent, small-volume, and bloody stools indicates disrupted and inflamed mucosa etiologies infectious (i.e., Shigella, Salmonella, E. coli, Campylobacter, amebiasis) idiopathic inflammatory bowel disease (ulcerative colitis, 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, 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 Campylobacter, Salmonella Food Eggs Salmonella Food Beef E. coli Food Poultry Campylobacter, Salmonella Food Pork C. perfringens, Y. enterocolitica Food Seafood Astrovirus, Vibrio Food Oysters Calicivirus, Vibrio Food Rice/pasta Bacillus cereus Water exposure Swimming pools Shigella Water exposure Contaminated water with cysts Giardia, E. histolytica, Cryptosporidium Travel history "Traveler's" diarrhea E. coli, Giardia, Salmonella, Shigella, Campylobacter Travel history Camping/hiking Giardia Past medical history Antibiotics/hospitalization C. difficile, rotavirus Pets Dog feces Yersinia enterocolitica Pets Turtles/reptiles Non-typhoidal Salmonella Pets Other animals/pets 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 Chronic Diarrhea Malabsorption syndromes Celiac disease Lactose intolerance Pancreatic insufficiency Diabetic neuropathy Inflammatory bowel disease Crohn disease Ulcerative colitis Other gastrointestinal causes Microscopic colitis Irritable bowel syndrome Endocrinological Carcinoid Gastrinoma Drug-induced Quinidine Colchicine Chemotherapy Other Severe combined immunodeficiency Arsenic poisoning Vitamin C toxicity Vitamin B3 deficiency Treatment Medical supportive care modalities oral rehydration 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 Vibrio cholera oral vancomycin for C. difficile infection rifaximin for small intestinal bacterial overgrowth anti-motility agents indication not indicated for infectious diarrhea modalities loperamide bismuth salicylate Complications Dehydration