More than 120 people got sick in a norovirus outbreak aboard a Princess Cruises ship sailing to Alaska and Canada, health officials said. A total of 102 passengers aboard the Ruby Princess, which departed from San Francisco on June 12, reported being ill, along with 23 crew members, the Centers for Disease Control and Prevention said in a statement. Most of the people who became sick said their main symptoms were diarrhea and vomiting. Norovirus is known for spreading in close-contact environments such as cruise ships, where shared dining spaces and frequently touched surfaces can make containment difficult once an outbreak begins.Most people who contract the virus begin showing symptoms within 12-48 hours of exposure, which can quicken the spread of outbreaks in confined settings, health officials say.The 20-day cruise sailed across parts of Alaska and Canada before returning to San Francisco on Thursday, as scheduled. The Ruby Princess cruise ship (Wikimedia/Ivan T)Princess said in a statement to The Independent that “a limited number of guests reported mild gastrointestinal illness” while aboard the ship. “Our crew responded promptly by implementing enhanced sanitation protocols across the ship, and cases have since decreased and remain low,” Princess added in the statement. Afer arriving at its destination, the ship “will be undergoing comprehensive cleaning and disinfection” before it takes off on its next cruise, Princess said. Sick passengers and crew members were isolated after contracting the virus and the ship increased cleaning and disinfection procedures, the CDC said.This year, there have been seven outbreaks of gastrointestinal illness aboard cruise ships that have met the CDC’s guidelines to issue a public notice. Two of the prior outbreaks this year were caused by E.coli, while the other five were norovirus. Two of the previous norovirus outbreaks this year were also aboard Princess cruise ships.