Traveler's diarrhea is commonly associated with which etiologic agent?

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

Answer: (B)

Traveler's diarrhea is most often caused by enterotoxigenic Escherichia coli. This strain adheres to the small intestine and releases toxins that drive a secretory, watery diarrhea after ingestion of contaminated food or water during travel. The illness typically presents as watery stools with abdominal cramps and sometimes mild fever, occurring within a day or two of exposure and usually resolving without severe complications. Other organisms listed can cause gastroenteritis, but they are not the classic, most common cause of traveler's diarrhea: Aeromonas hydrophila is linked to contaminated water or seafood but is less typical worldwide; Proteus mirabilis is mainly a urinary tract pathogen; Vibrio parahaemolyticus is associated with seafood, especially undercooked shellfish. Thus, Escherichia coli best fits the common travel-associated etiology.