The Centers for Disease Control and Prevention (CDC) is investigating an outbreak of more than 150 cases of an unknown illness on the cruise ship Queen Victoria in the Pacific, the agency said Monday.

The luxury ocean liner, operated by Cunard Cruise Line, left San Francisco on Wednesday en route for Hawaii, about a month into a 107-night world tour.

About 140 of the ship’s 1,800 passengers and 970 crew reported symptoms of gastrointestinal illness, including diarrhea and vomiting, when it was docked at Fort Lauderdale, Fla., on Jan. 22. Sickness totals are from the entire voyage and do not represent current illness, the CDC said.

Cunard told the agency it has stepped up cleaning and disinfection on the ship to combat transmission of the unknown illness, and it is isolating infected passengers and crew.

The Hill has reached out to Cunard Cruise Line for comment.