(CNN) — More than 230 people on board the luxury Queen Mary 2 cruise ship have fallen ill with the highly contagious norovirus stomach bug. The US Centers for Disease Control and Protection (CDC) reported the outbreak just as the Cunard cruise liner was nearing the end of a four-week-long re turn voyage from the UK to the Caribbean. Queen Mary 2 regularly sails transatlantic crossings. It’s a journey — and a ship — designed to hark back to the golden age of luxury ocean liners. Cunard is owned by Carnival Corporation The vessel set sail on March 8 from Southampton and is due to return to the English port on April 6. During the voyage, 224 of the 2,538 passengers have fallen sick with the gastrointestinal virus, while 17 of the 1,232 crew members have also became unwell, according to CDC data. ‘The cruise ship virus’ Infectious disease expert Dr. William Schaffner, a professor at Vanderbilt University Medical Center, told CNN Travel earlier this year that norovirus is “known obviously as the cruise ship virus.” Norovirus is notoriously contagious, and therefore people in close quarters — such as a cruise ship — may be more likely to spread the disease. The CDC also notes the virus’ spread among travelers in other similarly 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,” said Schaffner. “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.” Predominant symptoms on board the Queen Mary 2 are diarrhea and vomiting. The CDC said that Cunard Line increased cleaning and disinfection on board the ship following the recent confirmed outbreak. Infected passengers have also been quarantined from others on board and stools are being tested. The CDC’s Vessel Sanitation Program (VSP) which keeps track of outbreaks at sea, also confirmed it’s “remotely monitoring the situation, including review of the ship’s outbreak response and sanitation procedures.” The VSP also confirmed that Cunard Line had consulted with the program about cleaning procedures on Queen Mary 2, and reporting illness on board. CNN Travel reached out to Cunard Line for comment. A rise in illness at sea? The outbreak comes on the heels of the worst year for cruise ship-based gastrointestinal outbreaks in over a decade, according to CDC data. The majority of these record-breaking 2024 gastrointestinal outbreaks at sea were norovirus-related. The CDC reported a total of 16 gastrointestinal cruise outbreaks across 2024, the highest in over a decade, while in 2023, there were a total of 14 reported outbreaks. Speaking to CNN Travel in January, a CDC spokesperson said that “while 2023 and 2024 both had higher numbers of cruise ship outbreaks than in years prior to the pandemic, we do not yet know if this represents a new trend.” There were fewer reports in the 2020-2022 period, during which time the cruise industry shut down — and then slowly restarted — in the wake of the Coronavirus pandemic. Back in 2019, there were 10 reported outbreaks, according to CDC data. “Cruise ship travel during the Covid-19 pandemic was limited, and prior to that, we saw that the rates of gastrointestinal illness on cruise ships decreased (during 2006-2019),” said the CDC spokesperson. CDC data only covers ships under the agency’s jurisdiction — meaning the ship’s voyage must include a US port, a foreign itinerary and be carrying more than 13 passengers. While this criteria counts for a lot of the world’s cruise ship fleet, it doesn’t cover every vessel traversing the world’s oceans. In a statement provided to CNN Travel in January, industry organization Cruise Lines International Association said: “Incidents of illness onboard cruise ships are extremely rare.” The CDC also notes that “outbreaks are found and reported more quickly on a cruise ship than on land,” thanks to reporting protocols. On average, some 19-21 million instances of norovirus illness occur in the US every year, according to the CDC. So far in 2025, the CDC has reported 11 outbreaks of gastrointestinal illness on board cruise ships, including the Queen Mary 2 infection. Of these instances, nine were caused by norovirus. Staying healthy on board Cruise passengers who present stomach bug symptoms can help limit the spread of infection by “promptly reporting their illness if they are sick and following medical staff recommendations,” according to the CDC spokesperson who advised CNN Travel earlier this year. Passengers are also instructed to practice “washing their hands often, especially after using the toilet and before eating or drinking.” Cruise ships also pride themselves on taking steps to control outbreaks, as Queen Mary 2 recently demonstrated. Measures include quarantining passengers and crew with symptoms, and increasing cleaning and disinfection of impacted vessels. Still, infectious disease expert Schaffner said that due to the supremely infectious nature of norovirus, “it is likely to go beyond all those barriers and interventions that have been put in place” by cruise lines. Schaffner’s advice to prospective cruise passengers is “number one, if you’re feeling at all ill, stay home, rebook for a later cruise. “Number two, pay meticulous attention to all the hygienic instructions that you are given on the cruise ship, and pay particular attention to hand hygiene. And in this circumstance, soap and water is actually better than using the sanitary hand wipes or lotions that we use, because norovirus is not very affected by the alcohol that’s in the hand wipes and the lotions.” ...read more read less