What is the most common cause of traveler's diarrhea?

Traveler's diarrhea is most commonly caused by entero-toxigenic Escherichia coli (ETEC), which is a specific strain of E. coli. This form of E. coli is particularly associated with food and water contamination in regions where sanitary conditions may be inadequate. When travelers consume contaminated food or water, the E. coli can proliferate in the intestines and produce toxins that lead to diarrhea characterized by frequent, watery stools.

The prevalence of E. coli as the main culprit in cases of traveler's diarrhea is well documented in travel medicine literature, making it a significant health concern for individuals traveling to areas with higher risks of gastrointestinal infections. Understanding this helps in preventing traveler's diarrhea through safe food and water practices.

In contrast, while other organisms listed, such as Salmonella, Norovirus, and Giardia lamblia, can cause gastrointestinal illness, they are less frequently responsible for traveler's diarrhea specifically. Salmonella is typically associated with undercooked poultry or eggs, Norovirus often spreads in crowded settings, and Giardia lamblia is more linked with contaminated water sources, but these are not the primary causes of travel-related diarrhea together with E. coli infections.