A highly contagious form of stomach flu sickened hundreds of passengers during a worldwide voyage on the famed Queen Elizabeth 2 cruise ship in what health officials called an unusually large outbreak.
The Centers for Disease Control and Prevention reported 276 passengers and 28 crew members had come down with norovirus by the time the ship docked Wednesday in San Francisco for a regularly scheduled stop, though only four passengers remained sick.
The CDC boarded the QE2 on Friday in Acapulco, Mexico, to investigate the outbreak.
Investigators determined the emergency sanitation measures put in place by the ship's crew, from disinfecting casino chips to halting self-service at the ship's buffet, were containing the outbreak.
"This one was a good example where they had a lot of cases but they did gain control over the spread of infection," Ames said.
The infections affected nearly 17 percent of the ship's 1,652 passengers, a particularly high percentage, said Jaret Ames, acting chief of the CDC's vessel sanitation program. By comparison, a norovirus outbreak last month aboard the world's largest cruise ship, Royal Caribbean's Freedom of the Seas, infected 338 passengers out of 3,823, or less than 9 percent.
In rare cases, the elderly and young children can die from dehydration caused by norovirus symptoms. The infection, which ranks second only to the common cold in reported cases, usually clears up in two or three days with no lasting effects.
No passengers have canceled their tickets as a result of the outbreak, said Brian O'Connor, a spokesman for Cunard Line, the company that operates the QE2.
The ship departed Jan. 8 from New York on the first leg of its 106-day cruise around the world. It was to leave San Francisco for Honolulu on Wednesday night.