CDC: Royal Caribbean cruise has more than 600 sick passengers, crew

More than 600 passengers and crewmembers on a Royal Caribbean cruise have been sickened by a gastrointestinal virus, according to federal health officials.

Thus far, 577 passengers and 49 members of the crew have developed symptoms of in the illness including diarrhea and vomiting, the Centers for Disease Control and Prevention told CBS News Monday.

CDC officials boarded the cruise ship Sunday in St. Thomas. They will remain on the ship for the duration of the cruise, which was cut short early and is expected to reach its home port in Cape Liberty, N.J. on Wednesday.

On Sunday evening, the cruise line said the outbreak of the gastrointestinal illness with vomiting and diarrhea "spiked over the weekend," but it did not disclose a tally of sickened people at the time.

The CDC said last Friday that 281 of the 3,050 passengers aboard the 15-deck cruise, reported getting sick during the voyage that left N.J. on Tuesday.

Sick passengers have "responded well to over-the-counter medication being administered onboard the ship," Janet Diaz, a Royal Caribbean spokesperson, said Sunday.

Health officials will likely know by Wednesday whether the culprit behind the outbreak was norovirus, a contagious infection that can lead to stomach pain, diarrhea, nausea and vomiting. Between 19 and 21 million cases of norovirus occur in the U.S. each year, resulting in up to 70,000 hospitalizations and 800 deaths. 

The CDC added extra sanitary measures have been undertaken to aggressively clean the ship, and stool samples have been taken from some infected persons for analysis.

The CDC’s Vessel Sanitation Program, which tracks disease outbreaks on ships, points out that norovirus can spread easily on the boat because of close quarters with other passengers and because people joining the ship may carry a virus which spreads to crew and fellow passengers.