Hawaiian health officials said they were contacted to run laboratory tests for Norwegian Cruise Line to determine what sickened more than 400 of the 2,500 passengers aboard the Pride of Hawaii.The tests will confirm if the stricken passengers are suffering from Norovirus or some other ailment.

The afflicted passengers fell ill after the vessel left Honolulu Harbor on Monday. The ship arrived at Maui on Friday and was expected to continue on to Kauai.

Passengers suffering from nausea, vomiting and diarrhea and their cabinmates were quarantined in their staterooms for 24 hours.

NCL said it was giving those passengers a $200 on-ship credit.

Passengers booked on the Pride of Hawaii’s next cruise were informed of the outbreak to give them the option not sailing, NCL said.