You must have been reading the CC HAL board. :) I saw that post regarding the Statendam.

I'll give the same reply here as I did over there. It's a viral outbreak onboard - usually a norovirus outbreak. To stop it from spreading, the crew onboard goes on overdrive cleaning the ship, minimizing passenger physical contact with each other, and quarantining the passengers that are showing symptoms. It probably happens more often than we're aware of since closed environments (like cruises, nursing homes, hospitals) are the easiest places for viruses such as this to multiply. Luckily, they tend not to carry over from cruise to cruise too often.

Masaki