- An abnormal increase in stool water content, volume, or frequency (≥3 times in 24 hours) for <14 days duration
- Most commonly secondary to infectious etiology; often self-limited
- Acute viral diarrhea (50–70%)
- Most common cause of infectious diarrhea; noninflammatory (watery)
- Frequently presents with associated nausea and/or vomiting
- Symptoms usually develop after an incubation period of ~1 day and last for 1 to 3 days; typically self-limited
- Bacterial diarrhea (15–20%)
- Most common infectious cause of inflammatory (bloody) diarrhea
- Incubation period variable; diarrhea caused by preformed enterotoxin presents within 1 to 6 hours of contaminated food ingestion, whereas bacterial infection typically presents within 1 to 3 days.
- Symptoms usually resolve in 1 to 7 days; antibiotic use attenuates length and/or severity of disease.
- Suspect when concurrent illness in others who have shared potentially contaminated food.
- Protozoal infections (10–15%)
- Typically cause noninflammatory (watery) diarrhea
- Long incubation period and prolonged disease course; symptoms develop approximately 7 days after exposure and commonly last >7 days.
- Suspect when outbreaks of watery diarrhea in areas with contaminated water or food supply
- Traveler’s diarrhea (TD) typically begins 3 to 7 days after arrival in foreign location and resolves within 5 days; rapid onset, generally self-limited
- In developing countries, acute diarrhea is more common in children; no age predilection in developed countries
- Acute diarrhea accounts for >128,000 U.S. hospital admissions and ~2.5 million annual deaths worldwide (1).
- The WHO categorizes acute diarrhea (symptoms <14 days) into watery and bloody (dysentery) subtypes.
- Second leading cause of death in children <5 years and seventh leading cause of death among all ages worldwide
- Affects 11% of the general population
- In developing world, acute diarrhea is largely due to contaminated food and water.
Etiology and Pathophysiology
- Escherichia coli
- Salmonella, Shigella, Campylobacter jejuni
- Vibrio parahaemolyticus, Vibrio cholerae
- Yersinia enterocolitica
- Clostridium difficile
- Staphylococcus aureus
- Bacillus cereus
- Clostridium perfringens
- Listeria monocytogenes
- Mycobacterium avium complex (in immunocompromised)
- Mycobacterium tuberculosis (in immunocompromised)
- Rotavirus and Norovirus (most common)
- Cytomegalovirus (CMV) (in immunocompromised)
- Giardia lamblia
- Entamoeba histolytica
- Cryptosporidium (in immunocompromised)
- Cystoisospora belli
- Cyclospora, Microspora (in immunocompromised)
- Pathophysiology (1)
- Noninflammatory: most commonly viral; increased intestinal secretions without disruption of intestinal mucosa; watery character
- Inflammatory: generally invasive or toxin-producing bacteria; disrupts mucosal integrity with subsequent tissue invasion/damage; bloody character
- Viral diarrhea: changes in small intestine cell morphology, including villous shortening, increased number of crypt cells, and increased cellularity of the lamina propria
- Bacterial diarrhea: Bacterial invasion of colonic wall leads to mucosal hyperemia, edema, and leukocytic infiltration.
- Travel to developing countries
- Failure to observe food/water precautions
- Immunocompromised host (HIV, malignancy, chemotherapy)
- Recent hospitalization
- Antibiotic use
- Proton pump inhibitor (PPI) use
- Daycare exposure
- Fecal-oral sexual contact
- Nursing home residence
- Pregnancy (12-fold increase for listeriosis) (1)
- Frequent handwashing reduces incidence of diarrhea by approximately 30%.
- Proper food and water precautions, particularly during foreign travel—“boil it, peel it, cook it, or forget it”
- Avoid undercooked meat, raw fish, unpasteurized milk.
- Rotavirus vaccine (for infants)
- Typhoid fever and cholera vaccine (for travel to endemic areas)
- TD Prevention:
- Pretravel counseling on high-risk food/beverage
- Consider daily prophylaxis with bismuth subsalicylate (BSS) in all travelers (can reduce the risk of TD by up to 60%); usual dosing of 2 tablets (262 mg each) or 2 oz (60 mL) liquid formulation 4 times daily
- Do not use routine antibiotic prophylaxis.
- When indicated, the Infectious Disease Society of America recommends chemoprophylaxis with fluoroquinolones: norfloxacin 400 mg/day or ciprofloxacin 500 mg orally once or twice daily.
- Probiotics, prebiotics, and synbiotics have unclear benefit as prophylaxis.
Commonly Associated Conditions
- Inflammatory bowel disease (IBD)
- Immunocompromised (HIV, malignancy, chemotherapy)
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