The U.S. Centre for Disease Control will send doctors and experts aboard the Royal Caribbean cruise ship Explorer of the Seas when it docks in St. Thomas in the U.S. Virgin Islands on Sunday. The ship has about 280 very sick people aboard. Passengers report vomiting and diarrhea. In addition, another 22 crew members are ill. It is not clear what has hit the ship. A total of 3,050 passengers and 1,165 crew members are aboard the Explorer of the Seas. The CDC said Royal Caribbean officials have taken action, including increasing disinfection procedures and preparing new crew members to join the ship mid-voyage.