Cruise Ships Report Highest Gastrointestinal Infection Rates in a Decade
The cruise industry is experiencing unprecedented growth, with an estimated 37.1 million passengers anticipated to set sail in 2025, as per the Cruise Lines International Association (CLIA). However, a concerning trend has emerged alongside this expansion: the occurrence of gastrointestinal infections on cruise ships has reached the highest levels seen in over ten years.
Recent data from the U.S. Centers for Disease Control and Prevention (CDC) indicates that 2024 was the worst year for gastrointestinal outbreaks on cruise vessels in a decade, primarily attributed to the highly contagious norovirus.
In December alone, five cruise ships reported norovirus outbreaks, affecting hundreds of passengers aboard vessels operated by Cunard Line, Holland America, and Princess Cruises. The CDC classifies an outbreak as occurring when at least 3% of passengers or crew members exhibit gastrointestinal symptoms that require medical attention.
Norovirus has long been associated with cruise ships due to its ability to spread rapidly in environments where people are in close quarters. Dr. William Schaffner, an infectious disease specialist at Vanderbilt University Medical Center, emphasizes that norovirus is notoriously contagious, making it easier to transmit among passengers in confined spaces.
"This virus can infect individuals with very few viral particles, meaning a small dose is sufficient for infection," Dr. Schaffner noted. "It can survive on surfaces for days, which increases the likelihood of transmission if one comes into contact with contaminated surfaces."
Norovirus infections typically peak during the winter months, with seasonal variations in intensity. The current season is reportedly more severe than usual, contributing to the spike in outbreaks as reflected in the CDC's December data.
While the Cruise Lines International Association asserts that incidents of illness aboard cruise ships are rare, the CDC points out that outbreaks are detected and reported more swiftly on cruises compared to land-based settings, thanks to established reporting protocols.
Despite the increase in reported outbreaks, the CDC maintains that the figures for 2023 and 2024 may not signal a long-term trend, given that there were fewer reports from 2020 to 2022 when the cruise industry was significantly impacted by the COVID-19 pandemic. In 2019, the CDC recorded only ten outbreaks.
The CDC's data pertains only to cruise ships operating under its jurisdiction, meaning vessels must include a U.S. port in their itinerary and carry more than 13 passengers. This criterion encompasses a substantial portion of the global cruise fleet but does not account for every cruise operating worldwide.
In addition to norovirus, other gastrointestinal illness outbreaks were noted in 2024, including a salmonella-related incident on the Royal Caribbean's Radiance of the Seas and an E. coli outbreak aboard the Silver Nova from Silversea Cruises. The cause of another gastrointestinal illness reported on the Allure of the Seas remains unidentified.
In total, the CDC documented 16 gastrointestinal outbreaks on cruise ships in 2024, marking the highest annual count in over ten years, compared to 14 outbreaks in 2023.
