CDC Records 23 Cruise-Ship Illness Outbreaks in 2025, Norovirus Dominates

The Centers for Disease Control and Prevention logged 23 gastrointestinal illness outbreaks aboard cruise ships in its jurisdiction during 2025, with norovirus identified as the causative agent in 18 of them, according to the agency's Vessel Sanitation Program.

The Details

The CDC's Vessel Sanitation Program maintains a public record of gastrointestinal outbreaks on cruise ships that fall under its oversight. For 2025, that record lists 23 separate outbreaks, with norovirus accounting for the overwhelming majority of cases where a cause was identified.

The agency publishes outbreak notices when a voyage meets two specific criteria: the ship must be under VSP jurisdiction, and the voyage must have 3 percent or more of passengers or crew reporting symptoms of gastrointestinal illness to the ship's medical staff. The CDC states: "We post outbreaks when they meet both of the following: Ship is under VSP jurisdiction ... [and] voyage has 3% or more of passengers or crew reporting symptoms of GI illness to the ship's medical staff."

The 2025 tally comes amid broader attention to cruise-ship illness patterns. WLWT, citing CDC data, reported that cruise-ship outbreaks have risen in recent years and that three outbreaks had already been recorded in 2026 at the time of that outlet's publication. The 2025 figure of 23 outbreaks provides a concrete baseline for comparison as those newer cases develop.

Among the 23 recorded outbreaks, norovirus was the most frequently identified pathogen. The CDC's outbreak listings designate norovirus as the causative agent in 18 of the 23 incidents, underscoring the virus's persistent role in maritime illness clusters.

Context

The CDC defines acute gastroenteritis illness for cruise-ship reporting purposes as three or more loose stools within a 24-hour period, or vomiting accompanied by another qualifying symptom. This definition guides both ship medical staff and the Vessel Sanitation Program in determining which cases count toward the outbreak threshold.

Long-term CDC data offers additional framing for the 2025 numbers. An analysis of 252 cruise ships from 2006 through 2019 found that passenger acute gastroenteritis illness rates were higher on larger vessels and on voyages lasting longer than seven days. Those findings suggest that ship size and itinerary length are relevant variables when assessing outbreak risk.

Norovirus itself is a highly contagious pathogen that typically spreads through contaminated food, water, or surfaces. Its prevalence in the 2025 cruise-ship dataset aligns with its established reputation as a common cause of gastrointestinal illness in closed or semi-closed environments where large numbers of people share dining facilities and living spaces.

The CDC's Vessel Sanitation Program conducts regular inspections and provides guidance to the cruise industry, but the 2025 outbreak count reflects reported incidents rather than an estimate of total unreported cases.

What's Next

The CDC will continue to monitor and log gastrointestinal outbreaks on cruise ships under VSP jurisdiction as they occur. Ships remain required to report cases of acute gastroenteritis to their onboard medical staff, and voyages crossing the 3 percent symptom threshold will continue to be posted on the agency's public outbreak list. The three outbreaks recorded in early 2026, as noted by WLWT, will add to the data set in coming months.