SAN FRANCISCO — The Centers for Disease Control and Prevention is investigating an outbreak on a luxury cruise ship where more than 150 people have reported gastrointestinal illness, including diarrhea and vomiting.

The Queen Victoria, operated by Cunard Cruise Line, departed San Francisco Wednesday on its way from Florida to Hawaii. The ship is carrying 1,800 passengers and 970 crew members.

The cause is unknown. Cunard told the CDC that the ship increased cleaning and disinfection, and isolated ill passengers and crew.