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

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

Answer: (D)

Traveler’s diarrhea often results from ingesting contaminated food or water while traveling, especially in areas with variable sanitation. The most common culprit is enterotoxigenic Escherichia coli. This pathotype doesn’t invade the gut tissue but releases toxins that stimulate secretion in the small intestine, leading to watery, non-bloody diarrhea with cramps. The illness typically starts soon after exposure and is usually self-limited, though oral rehydration is important and antibiotics may be used in more severe cases or if symptoms persist.

Other organisms can cause gastroenteritis, but they’re not the classic match for traveler’s diarrhea. Aeromonas hydrophila is associated with freshwater exposure and can cause gastroenteritis, Vibrio parahaemolyticus is linked to raw or undercooked seafood and can give watery diarrhea, and Proteus mirabilis is more commonly implicated in urinary tract infections and wound infections rather than traveler's diarrhea. The pattern of illness and the epidemiology most consistently point to enterotoxigenic E. coli as the typical agent.