MIAMI -- Yet another Princess Cruises ship has returned to port with passengers sick from a severe stomach virus.

Last week, the Ruby and Crown Princess ships both had norovirus outbreaks involving nearly 500 people during Caribbean cruises.

On Saturday, the Crown Princess returned from a Caribbean cruise with 364 sick passengers and 30 sick crew members, cruise line spokeswoman Julie Benson said. In all, about 3,100 people were on board.

Then, on Sunday morning, the 3,000 passengers and crew on board the Ruby Princess disembarked, Benson said. Of those on board, 92 passengers and 13 crew members were reported ill.

After being sanitized, the Crown Princess was sent out again.

This time, about 226 passengers and more than 63 crew members got sick on the ship.

The ship returned to port in Fort Lauderdale, Florida, on Thursday, two days early, for an extensive two-day cleaning, Princess Cruises said in a statement.

Passengers will get fully reimbursed for their cruise and their flights back home.

"We sincerely regret having to cut short our passengers' cruise vacations because of this highly unusual situation. We will, of course, be refunding their cruise fare, arranging flights home, including covering change fees if air was not booked through Princess, providing hotel accommodation if necessary, and offering a 25% future cruise credit," the cruise line said.

Princess is working with the Centers for Disease Control and Prevention's Vessel Sanitation Program to combat what officials suspect is norovirus.

Norovirus causes symptoms including diarrhea, vomiting and stomach pain, according to the CDC. It is spread from person to person through contaminated food or water or by touching contaminated surfaces.

The enhanced cleaning will include "thorough sanitization of all public spaces and surfaces including soft furnishing and carpets, railings, door handles and the like," Princess said, and staterooms will be cleaned more than once before the next guests board.

The next cruise is set to depart as scheduled on Saturday.