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- An abnormal increase in stool water content, volume, or frequency (≥3 in 24 hours) for <14 days duration
- 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.
- Suspect Clostridium difficile in patients with recent antibiotic use or hospitalization.
- 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 ~1.5 million annual deaths worldwide (1).
- 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
- Rotavirus and adenovirus most common in children <2 years, bacteria are more common in children >2 years
- In developing world, acute diarrhea is largely due to contaminated food and water (1).
Etiology and Pathophysiology
- Escherichia coli
- Salmonella, Shigella, Campylobacter jejuni
- Vibrio parahaemolyticus, Vibrio cholerae
- Yersinia enterocolitica
- C. difficile
- Staphylococcus aureus
- Bacillus cereus
- Clostridium perfringens
- Listeria monocytogenes
- Rotavirus and norovirus (most common)
- Cytomegalovirus (in immunocompromised)
- Giardia lamblia
- Entamoeba histolytica
- Isospora belli
- Cyclospora, Microspora
- Pathophysiology (1)
- Noninflammatory: most commonly viral; increased intestinal secretions without disruption of intestinal mucosa; watery
- Inflammatory: generally invasive or toxin-producing bacteria; disrupts mucosal integrity with subsequent tissue invasion/damage; bloody stools
- 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
- Antibiotic use
- Proton pump inhibitor (PPI) use
- Daycare exposure
- Fecal-oral sexual contact
- Nursing home residence
- Pregnancy (12-fold increase for listeriosis) (1)
- Frequent hand washing and alcohol-based hand sanitizers; hand washing promotion may reduce 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)
Traveler’s Diarrhea (TD) Prophylaxis
- 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%).
- Antibiotic prophylaxis should not be routinely used. Consider rifaximin use in patients at high risk of health-related complications of TD; fluoroquinolones no longer recommended for TD prophylaxis (2)
- Probiotics, prebiotics, and synbiotics have unclear benefit as prophylaxis.
Commonly Associated Conditions
- Inflammatory bowel disease (IBD)
- Immunocompromised (HIV, malignancy, chemotherapy)