Are Travelers’ Diarrhea and Norovirus Outbreaks on Cruise Ships Similar

Traditionally, it was believed that following simple dietary recommendations could prevent travelers' diarrhea (TD).

However, studies have shown that individuals who adhere to these guidelines can still fall ill. Recent research has identified critical bacterial causes of TD and has highlighted the regional variations in antibiotic resistance.

Published in JAMA Network Open on December 20, 2025, this Original Investigation utilized data from the GeoSentinel network. It analyzed antimicrobial susceptibility in four major pathogens from April 2015 to December 2022, focusing on Campylobacter, Shigella, nontyphoidal Salmonella, and diarrheagenic Escherichia coli.

Analyzing 859 cases, the study revealed alarming resistance rates: 75% for Campylobacter, 32% for nontyphoidal Salmonella, 22% for Shigella, and 18% for diarrheagenic E. coli.

Travelers in South Central Asia, Southeast Asia, and sub-Saharan Africa experienced the highest resistance rates.

Current treatment guidelines recommend fluoroquinolones or macrolides such as azithromycin for moderate-to-severe TD.

Resistance to macrolides was also notable, with 12% of Campylobacter and 35% of Shigella showing nonsusceptibility.

These researchers' findings suggest substantial geographic differences in antibiotic nonsusceptibility patterns in travelers' diarrhea; antimicrobial susceptibility from culture should be obtained when possible to inform self-treatment and clinician management strategies.

Throughout 2025, the U.S. CDC Vessel Sanitation Program continued to report norovirus outbreaks, which often included 'traveler diarrhea' cases. Norovirus is the most frequent cause of diarrheal outbreaks on cruise ships.

The CDC says they don't always know the cause of these outbreaks.

TD and norovirus infections on cruise ships are not clinically the same, though they share some overlapping symptoms and can both cause gastrointestinal distress.

Norovirus spreads explosively via contaminated surfaces, food, water, or people, making cruise ships hotspots for its transmission, says the CDC.

When a norovirus outbreak occurs onboard, passengers whose symptoms meet the case definition are asked to provide stool or vomitus samples. These samples are tested to determine the causative agent.

As of December 30, 2025, neither TD nor norovirus has a U.S. FDA-approved vaccine available.

However, norovirus vaccine candidates have been studied for years.