A norovirus outbreak aboard a Princess cruise ship sickened 125 passengers and crew members during a voyage in the North Pacific, according to health officials.
The Ruby Princess docked in San Francisco on Thursday morning following a 20-day round-trip Alaskan voyage which included a stop in British Columbia, Canada. On Wednesday, the U.S. Centers for Disease Control and Prevention said the norovirus outbreak affected 3% of the 4,176 people aboard and was reported to the CDC on June 28.
The Ruby Princess is seen docked in San Francisco on July 2, 2026.
Kassia Bonesteel
The main symptoms among those who fell ill were diarrhea and vomiting, according to the CDC. The crew aboard the ship increased cleaning and disinfection procedures, collected stool specimens for testing, and isolated the sick passengers and crew members, the report said.
“Princess Cruises can confirm that a limited number of guests reported mild gastrointestinal illness during the 20-day June 12 Ruby Princess voyage from San Francisco,” said the company in a prepared statement. “Our crew responded promptly by implementing enhanced sanitation protocols across the ship, and cases have since decreased and remain low.”
It was the third norovirus outbreak on a Princess cruise ship this year, according to the CDC, the most among cruise lines. In May, 160 passengers and crew members fell ill aboard the Caribbean Princess during a voyage that began in Fort Lauderdale, Florida. In March, norovirus sickened 153 people aboard the Star Princess during another Caribbean cruise.
Lindblad Expeditions had two norovirus outbreaks on its National Geographic Sea Bird expedition cruise ship in May and June.
Commercial passenger vessels carrying more that 13 or more passengers and operating in U.S. waters ships are required to track and report illnesses at least 24 hours before arriving at a U.S. port as part of the CDC’s Vessel Sanitation Program.
According to the CDC, norovirus is the most common cause of gastrointestinal illness outbreaks on cruise ships, accounting for 17 out of the 23 CDC-reported cruise ship outbreaks in 2025. Norovirus can be difficult to control on cruise ships because of the close living quarters, shared dining areas, and rapid turnover of passengers, while the virus can persist on surfaces for days or weeks and is resistant to common disinfectants.
However, acute gastrointestinal illnesses, including norovirus, are relatively infrequent on cruise ships. The CDC says norovirus outbreaks on cruise ships account for only 1% of all reported norovirus outbreaks.
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