A norovirus outbreak aboard the Ruby Princess sickened more than 120 passengers and crew members during a 20-day round-trip voyage to Alaska and Canada, according to the US Centres for Disease Control and Prevention, marking the third such outbreak on a Princess Cruises ship so far this year.
The CDC said 102 of the ship’s 3,032 passengers and 23 of its 1,144 crew members reported symptoms of acute gastrointestinal illness during the voyage, which departed San Francisco on June 12 and returned Thursday morning after stops in Alaska and British Columbia. The outbreak was formally reported to the agency’s Vessel Sanitation Program on June 28, with laboratory testing of stool samples confirming norovirus as the cause.
What Is Norovirus, and Why Does It Spread So Easily on Cruise Ships?
Norovirus is a highly contagious virus that causes acute gastroenteritis, with symptoms typically including sudden vomiting and diarrhoea, sometimes accompanied by stomach cramps, fever or body aches. According to the CDC, the virus can survive on surfaces for days or even weeks and spreads primarily through contaminated surfaces, food or close contact with infected individuals, making communal spaces like dining halls, buffet lines and shared cabins on cruise ships especially conducive to outbreaks. The illness is rarely dangerous for otherwise healthy individuals, though it can cause serious dehydration, particularly in young children, older adults and those with weakened immune systems.
Sarah Michaels, an assistant professor at Tulane University’s Celia Scott Weatherhead School of Public Health and Tropical Medicine, has previously said that outbreaks like these are frequently occurring in the wider community as well, but noted that settings with people living in close quarters, including cruise ships, day care centres and nursing homes, tend to make such illnesses far easier to detect and report.
Crew Moved Quickly to Contain Norovirus Outbreak
Princess Cruises said its crew responded promptly once the increase in gastrointestinal cases became apparent, implementing the ship’s enhanced sanitation protocols, isolating symptomatic passengers and crew members in their cabins, and consulting directly with CDC epidemiologists throughout the voyage. The company confirmed in a statement that a limited number of guests reported mild gastrointestinal illness during the sailing and said case numbers had dropped significantly in the final days before the ship’s return to port.
Passengers waiting to board the Ruby Princess for its next voyage Thursday afternoon said the cruise line had been transparent with them about the outbreak ahead of departure. One passenger, Stephanie Gomez, said she felt comfortable boarding given the additional time crews spent on a deep clean, adding that she planned to bring disinfectant spray for her cabin as an extra precaution. Another passenger, Luka Jackson, who was travelling to celebrate his grandparents’ anniversary, said the timing was unfortunate but that he trusted the line’s assurances that the ship was safe to sail.
A Pattern Across Princess Cruises Fleet
Thursday’s outbreak follows two earlier norovirus incidents on Princess Cruises vessels this year. In May, 160 passengers and crew members fell ill aboard the Caribbean Princess during a voyage that began in Fort Lauderdale, Florida, while in March, norovirus sickened more than 150 people aboard the Star Princess during a separate Caribbean sailing. Combined, the three outbreaks bring the total number of sick passengers and crew across the cruise line’s fleet this year to nearly 480, more than any other operator. Lindblad Expeditions is the only other line to record more than one outbreak in 2026, after its National Geographic Sea Bird experienced two separate norovirus incidents in May and June.
According to CDC data, norovirus remains the leading cause of gastrointestinal illness outbreaks on cruise ships, accounting for 17 of the 23 outbreaks publicly reported across the industry in 2025. So far in 2026, the agency has logged seven outbreaks meeting its public reporting threshold, five of which have been linked to norovirus and two to E. coli.
Federal Reporting Rules Keep Outbreaks in Public View
Under federal maritime regulations, any commercial vessel carrying 13 or more passengers operating in U.S. waters must report gastrointestinal illness data to the CDC at least 24 hours before arriving at a U.S. port as part of the agency’s Vessel Sanitation Program. The Ruby Princess underwent an intensive, hours-long turnaround clean at San Francisco’s Pier 27 before health officials cleared it to depart Thursday afternoon on its next scheduled sailing, a 10-night Alaska Inside Passage cruise.
The CDC recommends that travellers wash their hands frequently, promptly report any symptoms to a ship’s medical staff, and remain isolated while symptomatic to help limit the further spread of the virus, particularly during the peak summer cruising season, when ships are operating at or near full capacity.
