Which bacteria is associated with diarrhea after returning to the US from Mexico?

The association of Escherichia coli, particularly the Enterotoxigenic E. coli (ETEC) strain, with traveler's diarrhea after returning from areas like Mexico is well documented. ETEC is a leading cause of diarrhea among travelers, especially in regions where hygiene and sanitation practices may differ significantly from those in the traveler’s home country.

ETEC produces toxins that stimulate the intestinal lining, leading to an increased secretion of fluids and electrolytes, which in turn causes diarrhea. This strain is commonly acquired through contaminated food or water, and individuals who have recently traveled to Mexico are particularly susceptible due to the prevalence of this bacteria in that region.

Other bacteria, like Campylobacter jejuni, Salmonella, and Clostridium difficile, can also cause gastrointestinal infections, but they are less specifically linked to travel from the US to Mexico and the consequent gastrointestinal disturbances experienced. Campylobacter is often associated with undercooked poultry, Salmonella with various contaminated foods, and Clostridium difficile usually occurs after antibiotic exposure. Each of these has its own typical scenarios and transmission routes, differentiating them from the predominant cause of travel-related diarrhea attributed to ETEC.