It appears to be another case of the norovirus at sea.
ABC News reports that officials from the Centers for Disease Control and Prevention boarded a Royal Caribbean cruise ship Sunday to investigate an illness outbreak that has affected at least 300 people. They have fallen ill with gastrointestinal symptoms, including vomiting and diarrhea, that appear to be related to the highly contagious norovirus.
Approximately 280, or nearly 10 percent, of the 3,050 passengers aboard Explorer of the Seas have reported getting sick during a Caribbean cruise that left Cape Liberty, New Jersey, on Tuesday. Another 22 people—crew members—also reported feeling ill.
Janet Diaz, a Royal Caribbean spokesperson, said CDC representatives boarded the 15-deck ship as it made a port call in St. Thomas, the main island of the U.S. Virgin Islands.
At least two CDC officials, an epidemiologist and an environmental health officer, were expected to investigate and evaluate the outbreak response on the cruise liner.
During the previous port call in Puerto Rico, the ship underwent "extensive and thorough sanitizing" to help prevent more people from getting sick, the company spokeswoman said. The ship bypassed a scheduled stop at 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," Diaz said. "However, we feel it is best to make this itinerary modification to help prevent any more guests from becoming ill."
Norovirus is the likely culprit based on symptoms and close quarters of the cruise ship, but a scientific determination will have to wait until samples are tested in a lab. While there is no cure for the norovirus, Diaz said affected passengers and crew members are responding well to over-the-counter medications and that products proven to kill norovirus are being used to clean the ship.
Earlier this month, Royal Caribbean had a similar, but smaller outbreak on-board the Majesty of the Seas.