Sounds like the Diamond Princess Cruise Ship in Feb. 2000 when Covid broke out.
The course was more bad hygeine than anything else.
Probably the same here, start with the crew and their toilet habits.
The whole ship had bad hygiene?
Best period for cruises was from Sept 2021 to end of 2022 when my wife and I did half a dozen cruises all reduced to 50% off regular fare and EXTRA Hygiene practices on ship. Such as even in buffet no one could touch the food. It was served by a plastic gloved worker behind the counter. No moro-virus or covid breakouts. Masks were required in all public areas.