While Giardia can cause diarrhea and it is primarily spread through contaminated water, it's usually associated with freshwater sources in wilderness areas and the diarrhea does not typically have a fishy odor.

While E. coli can cause foodborne illnesses, it's less likely given the patient's recent travel history and the characteristics of her stool sample.

Shigella is another cause of severe diarrhea, often associated with poor sanitation conditions. However, the stool characteristics and the patient's travel history make Vibrio cholerae a more likely cause.

This is not a bacterial organism.