Just when cruise lines thought they might be headed for calmer waters ...
At least 162 passengers and 11 crew members have reported being ill on board Princess Cruises' Caribbean Princess, according to the Centers for Disease Control and Prevention.
The institute said health officers would board the ship in Houston to investigate the gastrointestinal illness, which is causing vomiting and diarrhea.
The news follows this week reports of sickness on another cruise ship, this one from the Royal Caribbean line.
Nearly 700 crew and passengers fell ill aboard the Royal Caribbean's Explorer of the Seas, the highest number of sick people reported on any cruise ship in two decades, CDC data show.
That ship returned home Wednesday, two days earlier than expected.
To compare the cruises, 5.22% of passengers on the Caribbean Princess reported being ill, versus 20.5% on the Explorer of the Seas.
The outbreak on board the Caribbean Princess has been confirmed as norovirus, according to Julie Benson, a spokeswoman for Princess Cruises.
Noroviruses spread easily and are a common cause of gastroenteritis, which produces vomiting and diarrhea.
Norovirus is also suspected on board the Explorer of the Seas, though the cause of the illness there has not been confirmed.
Caribbean Princess is expected in Houston early Friday. The seven-day cruise is being cut short by one day.
Sick passengers are being asked to stay in their cabins, while staff disinfect public areas such as restrooms and elevators.
The decision to cut the trip short was made based on forecasts for heavy fog, not the outbreak, Benson said.
CNN first learned of the stricken Princess ship from a Twitter post by the Houston Chronicle.