From this page – https://www.cnn.com/2025/01/03/travel/cruise-ships-worst-year-stomach-bugs-cdc-data
The cruise industry continues to balloon — with ever bigger, ever wilder boats and some 37.1 million cruise passengers set to take to the waters in 2025, according to industry body Cruise Lines International Association (CLIA).
But another statistic in the world of cruising is on the up, and it’s not a good one: the latest data from the US Centers for Disease Control and Prevention (CDC) suggests 2024 was the worst year for cruise ship-based gastrointestinal outbreaks in over a decade.
Norovirus at sea
CDC data suggests the majority of 2024 gastrointestinal outbreaks at sea were associated with the highly contagious norovirus. In December alone, five cruise ships were stricken with the vomiting bug, with hundreds of passengers reporting symptoms on Cunard Line, Holland America and Princess Cruises’ vessels. When an outbreak appears in CDC’s data, it means 3% or more of the ships’ passengers and crew presented gastrointestinal symptoms to medical staff.
Norovirus has long been associated with cruise ships because the virus spreads in environments where people are in close proximity. Infectious disease expert Dr. William Schaffner, a professor at Vanderbilt University Medical Center, notes norovirus is “known obviously as the cruise ship virus.”
Norovirus is notoriously contagious, and therefore people living in close quarters on a ship might be more likely to spread the disease. The CDC also notes the virus’ spread among travelers in other confined spaces such as camps, dormitories and hotels.
“This is a virus that can infect you with very few viral particles. In other words, the infectious dose is very small,” Schaffner tells CNN Travel. “It can persist for days or even a week on environmental surfaces, which means that if you put your fingers on a contaminated surface, you can pick up a few viral particles, touch your mouth and then initiate an infection.”
Norovirus tends to peak during winter months, and “this seasonal occurence of norovirus varies in intensity,” explains Schaffner.
