Leading Cause of Infectious Illness Among Travelers
Traveler's diarrhea is the leading cause of infectious illness among travelers, with acute diarrhea affecting 20-50% of travelers to developing countries and representing the most common diagnosis in those returning from endemic regions. 1
Epidemiology and Incidence
- Acute traveler's diarrhea has a reported incidence of 222 cases per 1000 ill returned travelers, making it the most frequent health problem encountered by travelers to developing countries 1
- Travel to high-risk areas in Latin America, Africa, the Middle East, and Asia is associated with diarrhea rates of 20% to 50% 2
- The syndrome affects millions of tourists each year and creates a substantial economic burden, with more than 60% of cases caused by bacterial enteropathogens 3
Primary Causative Pathogens
Bacterial Pathogens (80-90% of cases)
The bacterial causes, in order of frequency, include:
- Escherichia coli strains (most common): Enterotoxigenic E. coli (ETEC) is the leading pathogen, with enteroaggregative E. coli (EAEC) increasingly recognized as a major cause 1, 4
- Campylobacter species: Common bacterial cause, particularly in Southeast Asia where fluoroquinolone resistance exceeds 90% 1, 5
- Shigella species: Frequent cause of dysentery-type illness 1, 6
- Salmonella species (non-typhoidal): Less common but clinically significant 1, 3
- Other bacteria include Aeromonas, Plesiomonas, and non-cholera Vibrios 6, 3
Viral Pathogens
- Norovirus and rotavirus: Important causes, particularly in cruise ships and resort outbreaks, though less likely to cause fever 1
- Viral pathogens typically cause short-term illness that resolves before travelers seek medical attention 6
Parasitic Pathogens (approximately 10% of cases)
- Giardia lamblia: Most common parasitic cause, particularly in persistent diarrhea lasting weeks to months 1, 7
- Other parasites include Cryptosporidium, Cyclospora cayetanensis, and Entamoeba histolytica 1, 7
Clinical Presentation
- Acute traveler's diarrhea is defined as 3 or more episodes of loose stool within 24 hours 1
- Fever is self-reported in up to 30% of patients with traveler's diarrhea 1
- The majority of cases are self-limited, lasting less than 5 days when untreated (shorter with antibiotic therapy) 1
- Up to 50% of patients have no identifiable pathogen despite thorough investigation 1
Geographic and Seasonal Variation
- The etiology varies significantly according to destination, setting, and season 1
- Fluoroquinolone resistance patterns differ dramatically by region, with Southeast Asia showing the highest rates 1, 5
Critical Diagnostic Pitfall
A common pitfall is failing to distinguish between self-limited bacterial diarrhea and Enterohemorrhagic E. coli (EHEC/STEC) infection, as antibiotics are contraindicated in STEC due to increased risk of hemolytic uremic syndrome. 8