Norovirus sickens 125 on Princess Cruises ship after Alaska voyage

Norovirus sickened 125 passengers and crew on the Ruby Princess during a 20-day round trip from San Francisco to Canada and Alaska. The U.S. Centers for Disease Control and Prevention said 102 of 3,032 passengers and 23 of 1,144 crew members reported gastrointestinal illness, with diarrhea and vomiting the predominant symptoms.

The outbreak was reported to the CDC Vessel Sanitation Program on June 28, 2026, four days before the ship returned to San Francisco on July 2. Princess Cruises and the crew then increased cleaning and disinfection, collected stool specimens for testing, isolated ill passengers and crew, and consulted with the program, which was remotely monitoring the situation.

The timeline puts a hard edge on the cruise line’s disease-control promises. Passengers were still on board when the outbreak was logged with federal health officials, and the CDC’s own posting rules show how narrow the warning window can be: outbreaks are listed when a ship in its jurisdiction, including voyages with U.S. and foreign ports, has 3% or more of passengers or crew reporting gastrointestinal illness. On the Ruby Princess, the passenger illness rate crossed that threshold at about 3.4 percent, while the crew rate was about 2.0 percent.

The CDC identified norovirus as the causative agent, a pathogen it says is a common cause of cruise-ship outbreaks. The ship’s case count also arrived as cruise-ship illness drew wider scrutiny in 2026, with CDC-tracked outbreak listings showing additional gastrointestinal outbreaks on other cruise ships this year. For Princess Cruises, the Ruby Princess episode was the company’s third reported gastrointestinal outbreak of 2026, underscoring how quickly sanitation measures, isolation protocols and disclosure timing can still fall behind a virus already spreading inside a closed voyage.