Diarrhea in the returned traveller

Background

Microbiology

• Bacteria
  • Escherichia coli (entero-hemorragic (EHEC), entero-toxigenic (ETEC)): most common cause
    • Usually afebrile
    • Diffusely adherent E. coli (DAEC) also exists
  • Campylobacter jejuni: more common in SE Asia
  • Salmonella (non-typhoidal)
  • Shigella
  • Plesiomonas (unclear if cause of diarrhea)
  • Vibrio cholerae
  • Aeromonas
• Viruses
  • Norovirus: most common virus
  • Rotavirus
  • Enterovirus
• Parasites
  • Giardia lamblia: usually afebrile
  • Entamoeba histolytica
  • Cyclospora cayetanensis
  • Cryptosporidium
  • Strongyloides stercoralis
• And others 1

Epidemiology

• Usually defined as diarrhea (3 or more unformed stools per day), plus one of abdominal cramps, tenesmus, nausea, vomiting, fever, or fecal urgency, either while travelling
• Incidence among travellers from rich countries is 10 to 40%

Risk Factors

• Beach vacations are protective compared to VFR, adventure tours, or all-inclusive hotels
• Cruise ships are associated with explosive outbreaks of norovirus
• Lower rates in winter; higher during rainy seasons
• Higher rates of diarrhea requiring hospitalization in infants and toddlers

Investigations

• Blood cultures (if febrile)
• Stool culture or PCR for bacteria
• Stool for ova & parasites

Management

• If mild (1-3 stools daily with mild enteric symptoms), can treat with bismuth subsalicylate or loperamide
  • Avoid loperamide in patients less than 2 years, if they are febrile, or if their stools are bloody
• May benefit from antibiotics if diarrhea is severe, there are systemic symptoms, or it is interfering with their activities
  • Can decrease duration of diarrhea by about a day and a half
• Empiric treatment depends on country of origin
  • Ciprofloxacin 500 mg PO bid for 3 days, for countries with lower rates of resistance
  • Azithromycin 500 to 1000 mg PO daily for 3 days

Further Reading

• Traveler's Diarrhea: A Clinical Review. JAMA. 2015;313(1):71-80. doi: 10.1001/jama.2014.17006
• Statement on Travellers' Diarrhea by the Committee to Advise on Tropical Medicine and Travel (CATMAT) (available online)