State health officials said they were contacted to run laboratory tests for Norwegian Cruise Lines to determine what sickened more than 400 of the 2,500 passengers aboard the Pride of Hawaii.
The tests would confirm if the ill passengers were suffering from the Norwalk virus or some other disease, the officials said Friday.
The afflicted passengers on the interisland cruise ship 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 asked to remain quarantined in their rooms for 24 hours.
NCL said it was giving those passengers a $200 on-ship credit.
The company reported Friday that the outbreak had been confined to just the one ship, that the "Pride of Aloha" and "Pride of America" were not affected.
Passengers booked on the Pride of Hawaii's next cruise were informed of the outbreak to give them the option not sailing, NCL said.