Traveler's diarrhea pathophysiology

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Overview

Pathophysiology

  • The transmission and pathogenesis of traveler's diarrhea is dependent on the infectious agent.
  • The following table summarizes the natural reservoir, transmission, and pathogenesis of common infectious agents associated with traveler's diarrhea:
Infectious Agent Characteristics Reservoir Common Mode of Transmission Pathogenesis
E. coli (ETEC)
  • Gram-negative rod
  • Humans and animals
  • Fecal-oral route
  • Contaminated ground beef, unpasteurized mild, cheese, vegetables, or water
  • Enterotoxin-mediated: secretion of heat-labile toxin (LT) and heat-stable toxin (ST)
Campylobacter jejuni
  • Gram-negative rod
  • Humans and animals
  • Fecal-oral route
  • Contaminated meat, unpasteurized mild, cheese, vegetables, or water
  • Exposure to infected animals
  • Enterotoxin-mediated: secretion of cholera-like enterotoxin
Shigella spp.
  • Gram-negative rod
  • Humans only
  • Fecal-oral route
  • Contaminated meat and pork, unpasteurized mild, cheese, vegetables, or water
  • Low inoculum sufficient for infection (resistant to gastric acid)
  • Enterotoxin-mediated: secretion of Shiga toxin
  • Invasion of macrophages and induction of cellular apoptosis
  • Intracellular spread by actin polymerization processes (rocket propulsion)
Salmonella spp.
  • Gram-negative rod
  • S. typhi: Humans only
  • Other Salmonella spp.: Humans and animals
  • Fecal-oral route
  • Contaminated raw egg shells, poultry, unpasteurized mild, cheese, vegetables, or water
  • High inoculum sufficient for infection (inactivated by gastric acid)
  • Vi capsule endotoxin prevents opsonization and lysis
  • Spread through the reticuloendothelial system
Norovirus
  • Positive-sense, single-stranded RNA virus
  • Humans and animals
  • Fecal-oral route
  • Contaminated food, vegetables, and water
  • Fomites
  • Aerosol exposure
  • Virus uses P2 subdomain for binding and HBGA for attachment on host cell
Rotavirus
  • Double-stranded RNA virus
  • Humans and animals
  • Fecal-oral route
  • Fomites
  • Poorly understood pathogenesis
  • Viral replication in villous epithelium of host small intestine
Giardia lamblia
  • Anerobic, flagellated protozoan parasite
  • Humans and animals
  • Ingestion of cysts in water or uncooked foods
  • Fecal-oral route
  • Attaches to the epithelium by a ventral adhesive disc, and reproduces via binary fission
  • Usually luminal infection, no hematogenous spread
Entamoeba histolytica
  • Anaerobic parasitic protozoan with pseudopods
  • Humans
  • Rare (but present) in animals
  • Ingestion of cysts in water
  • Fecal-oral route
  • Excystation in the small intestine and migration to the large intestine
  • Luminal and extraluminal infection, hematogenous spread common
Cryptosporidium
  • Spore-forming parasite
  • Humans and animals
  • Ingestion of oocytes in water
  • Fecal-oral route
  • Minimally invasive, surface-level mucosal inflammation
  • Usually luminal infection, potential to infect biliary tree

References

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