Traveler's diarrhea is most commonly associated with which organism?

• A. Aeromonas hydrophila
• B. Escherichia coli
• C. Proteus mirabilis
• D. Vibrio parahemolyticus

Answer: (B)

Traveler’s diarrhea is most commonly caused by enterotoxigenic Escherichia coli. This organism produces toxins that stimulate the intestinal lining to secrete fluids, leading to watery, nonbloody diarrhea after ingestion of contaminated food or water in travel regions. ETEC is particularly widespread in many travel destinations, so it accounts for the majority of cases, making it the best answer.

Other organisms can cause gastroenteritis, but they are not the leading cause of travel-related illness. Aeromonas hydrophila can cause diarrhea, often associated with water exposure, but it is less common as the primary cause of traveler’s diarrhea. Proteus mirabilis typically causes urinary tract infections and less commonly gastrointestinal symptoms. Vibrio parahaemolyticus is linked to seafood consumption and can cause gastroenteritis, but it does not surpass ETEC in frequency as the traveler's diarrhea agent.