What causes traveler’s diarrhea?

    Written by:
    Katie Jantz

    Fact-checked

    by:

    Morgan Pfiffner, Graham Walker
    Last Updated: May 16, 2025

    Traveler's diarrhea is primarily caused by consuming contaminated food or water, often due to poor sanitation, which leads to infections from bacteria, parasites, or viruses. The most common bacterial culprits include Campylobacter jejuni, Escherichia coli, Salmonella, and Shigella, and prolonged cases may indicate a parasitic infection like Giardia intestinalis.

    Traveler’s diarrhea occurs due to the consumption of food and/or water contaminated with bacteria, parasites, or viruses, generally resulting from poor sanitation practices.[1] Infection leads to an increase in the excretion of fluid and electrolytes via the gastrointestinal tract, leading to diarrhea.[2]

    Most cases of traveler’s diarrhea are caused by pathogenic bacteria, with Campylobacter jejuni, Escherichia coli, Salmonella species, and Shigella species being the most common.[3] If traveler’s diarrhea lasts more than 2 weeks, the infection is more likely to be due to a parasite such as Giardia intestinalis.[2][1].