The CDC says that, among the 232 outbreaks of norovirus illness reported to CDC from July 1997 to June 2000, 57% were foodborne, 16% were due to person-to-person spread, and 3% were waterborne. In 23% of outbreaks, the cause of transmission was not determined. Among these outbreaks, common settings included restaurants and catered meals (36%), nursing homes (23%), schools (13%), and vacation settings or cruise ships (10%).
I note with some amusement how many folks repeat this statement or something like it to make excuses for cruise lines. Do you, or have you frequented such places? I have. Have you gotten NoroVirus from those places? Probably not. Why not?
Cruise lines well know that their ships can be breeding grounds for this aliment. Even a very small amount of the virus can cause infection. It survives prolonged periods on such surfaces as counters and door handles, and it can even become airborne under some circumstances. Some common disinfectants, such as alcohol-based waterless hand scrubs won't kill it.
If a ship does not do a thorough cleaning after an outbreak...literally scrubbing every surface which may be touched by food, passengers or crew with appropriate disinfectants, the virus will keep on thriving from cruise to cruise. Cruise lines know this, but appear to want to ignore the implications.
Everyone says that scrupulous hand-washing is key to NoroVirus prevention. Well, it certainly helps. But, as one of those who is very aware of this problem, and who comes into physical contact with many "strangers" on a daily basis, I have adopted some fairly stringent hand-washing protocols for myself and my wife. Nevertheless, we were infected on the May 20th, 2011 sailing of Sea Princess to Alaska.
On Sea Princess, I saw food recycled. And I don't just mean left-overs, of which there were many in the buffet. In the dining room, uneaten bread was transferred from one basket to another, without a care or concern that the passengers departing that table likely fingered the rolls. Tables were "wiped down" yes, but with a lick-and-a-promise. They might as well have licked the tables, for all the good it did.
So, "you pays your money and you takes your chance". Cruising is great if you don't get sick. We went on many, many cruises before this one and never got sick. So I believe you still have a good chance to maintain health on a cruise. Unless the virus has already snuck aboard. If it has, it will remain there indefinitely; unless a very thorough cleaning is undertaken. Sea Princess' recent delayed sailing to Alaska was apparently an attempt to do that, but how much could really be done in the few hours allotted? Not enough apparently, as NoroVirus was present on that cruise as well.