Norovirus Outbreak on Princess Cruise Ship Sickens 125 Passengers and Crew

A virus that causes stomach illness spread through a cruise ship traveling in the North Pacific Ocean, making 125 people sick. The ship, called the Ruby Princess, was run by Princess Cruises and carried more than 4,000 passengers and crew members. Health officials from the U.S. Centers for Disease Control and Prevention, known as the CDC, reported the outbreak on June 28. The ship had been on a 20-day round trip from San Francisco, stopping in Alaska and British Columbia, Canada, before returning to port on Thursday morning.

The illness is called norovirus, and it causes diarrhea and vomiting. About 3% of the 4,176 people on board got sick, which means roughly 1 out of every 33 people fell ill. The ship's crew worked quickly to stop the virus from spreading further. They stepped up cleaning and disinfecting, collected stool samples for testing, and kept sick passengers and crew members away from others.

Princess Cruises released a statement saying the number of sick guests was limited and that the cases were mild. The company said its crew acted fast by following stronger cleaning rules on the ship. "Our crew responded promptly by implementing enhanced sanitation protocols across the ship, and cases have since decreased and remain low," the company said. Officials confirmed that the situation improved before the ship returned to San Francisco.

This was the third norovirus outbreak on a Princess cruise ship in 2025, which is more than any other cruise line. In May, 160 people got sick on the Caribbean Princess during a trip that started in Fort Lauderdale, Florida. In March, 153 people came down with norovirus on the Star Princess during a Caribbean cruise. Another cruise company, Lindblad Expeditions, also had two norovirus outbreaks on its National Geographic Sea Bird ship in May and June.

Cruise ships are required by law to report illnesses to the CDC at least 24 hours before they reach a U.S. port. This rule applies to any passenger ship with 13 or more people that travels in U.S. waters. The CDC tracks these reports through a program called the Vessel Sanitation Program. This helps health officials watch for outbreaks and act quickly when one happens.

Norovirus is the most common cause of stomach illness outbreaks on cruise ships. So far in 2025, it has been responsible for 17 out of 23 outbreaks reported to the CDC on cruise ships. The virus is hard to control on ships because people live in close quarters, share dining rooms, and come and go quickly. The virus can also survive on surfaces for days or even weeks and does not always respond to regular cleaning products.

Even so, stomach illnesses like norovirus are not very common on cruise ships overall. The CDC says that cruise ship norovirus outbreaks make up only 1% of all reported norovirus outbreaks in the United States. That means the vast majority of norovirus cases happen on land, not at sea. Experts say that cruise lines and health officials continue to work together to keep ships as safe and clean as possible.