KINGSTON, Jamaica — US health officials on Sunday boarded a cruise ship docked in the US Virgin Islands to investigate an illness outbreak that has stricken at least 300 people with gastrointestinal symptoms.
The Centers for Disease Control and Prevention has said that 281, or nearly 10 percent, of the 3,050 passengers aboard Royal Caribbean International’s Explorer of the Seas have reported getting sick during a Caribbean cruise that left New Jersey on Tuesday. Twenty-two crew members also reported feeling ill.
Company spokeswoman Janet Diaz said CDC representatives boarded the 15-deck ship on Sunday afternoon as it made a port call in St. Thomas, the main island of the US Virgin Islands.
At least two CDC officials — an epidemiologist and an environmental health officer — were expected to conduct the investigation and evaluate the outbreak response on the cruise liner. The US health agency did not immediately respond to an e-mail and a call seeking comment about the work aboard the ship.
During the previous port call in Puerto Rico, the ship underwent ‘‘extensive and thorough sanitizing’’ to help prevent more people from getting sick, said the Royal Caribbean spokeswoman. It bypassed a scheduled stop to the company’s fenced-in beach destination in northern Haiti to sail directly to Puerto Rico’s capital.
‘‘This was a difficult decision to make; however, we feel it is best to make this itinerary modification to help prevent any more guests from becoming ill,’’ Diaz said.
The passengers and crew fell ill with symptoms including vomiting and diarrhea. They have ‘‘responded well to over-the-counter medication being administered on board the ship,’’ Diaz said.
Fast-spreading norovirus is often to blame for similar symptoms sweeping closed quarters like those on cruise ships, but a determination probably won’t be made until samples are tested in a lab.