Two recent Royal Caribbean cruises saw more than 500 on board become sick after outbreaks of stomach-related illnesses, leading five people to be hospitalized in one of the cases.
After departing Dec. 11 from Port Everglades in Florida, 332 of the 5,547 guests aboard the Independence of the Seas became sick with gastrointestinal illness, a spokesperson told NBC News.
The outbreak came less than a month after 209 of the 5,796 people aboard Ovation of the Seas ship reported symptoms, said Cynthia Martinez, a Royal Caribbean International cruise line spokeswoman. The ship returned to Sydney on Dec. 7 at the end of a 14-night cruise that departed from Singapore on Nov. 23.
"Those affected by the short-lived illness were treated by our ship's doctors with over-the-counter medication," Martinez told The Associated Press in an email about the Ovation of the Seas outbreak.
A similar statement was given to NBC News regarding the incident on the Independence of the Seas.
She said sanitation experts were flown in to perform "enhanced sanitary procedures" to supplement routine cleaning protocols and "minimize the risk of a recurrence."
Martinez said she had no details on the type of gastrointestinal illness and would not provide conditions of the hospitalized guests out of privacy concerns. A specific type of gastrointestinal illness was also not specified for the outbreak aboard the Independence of the Seas.
Australia's Health Department in Tasmania confirmed five passengers required treatment at Royal Hobart Hospital, where Dr. Mark Veitch, director of public health, said in a statement that the ship was using established protocols to manage the illness and limit its spread. He added that these types of outbreaks and requests for medical assistance for passengers are "not uncommon" in big ships.
It was not clear if any passengers aboard Independence of the Seas required hospitalization.
The U.S. Centers for Disease Control and Prevention tracks gastrointestinal illness reports on ships sailing from foreign ports to the U.S. The Ovation of the Seas outbreak falls outside CDC jurisdiction because of the ship's location.
The CDC did not immediately respond to a request for comment regarding the outbreak aboard the Independence of the Seas.
The CDC's online database lists 10 outbreaks this year on ships in which more than 3 percent of those on board reported symptoms of "diarrheal disease."
The last outbreak listed in the database involving a Royal Caribbean cruise was a case of norovirus in February 2016 aboard the Anthem of the Seas.
The husband of one Ovation of the Seas passenger hospitalized at Hobart said his wife had eaten "undercooked chicken" on board. "Her condition continued to worsen and I thought she was going to die in front of me," said the passenger, who spoke to the AP on condition of anonymity, citing privacy issues. He said she was recovering in the intensive care unit.
The ship has been on a New Zealand itinerary and is now headed back to Sydney.