You said -- "I'm gonna take a WAG that the hotel staff isn't primarily Swedes, Germans, or Irish and English isn't their 1st language . And some of them have, oddly enough, the same social security number."
Well, I would have to disagree with the characterization of that, in terms of this Norwalk Virus. That stuff is highly contagious and spreads rapidly and can be picked off doorknobs and counter-tops and can easily be resident in crowded areas.
When an "outbreak" happens, it's a literal "explosion". That's how contagious that stuff is.
In areas with a *lot* of people passing through, you're going to end up with infections. Since it's *so highly contagious* -- and I've seen that *directly* with three of us in a family getting it within hours of each other and not having any sanitary problems in our household -- that stuff can jump from *anyone* to anyone else.
So, although those employees may not speak English very well and some of them may have those same numbers that you talk about -- I'll assure you that people with proper numbers and ones who speak perfect English are spreading to others with equally good numbers and good English.
Regards,
Star Traveler
P.S. -- And part of the problem of guarding yourself against this has to do with the period of time that you are contagious, versus the time when the symptoms appear, to the point where you know what you've got. That time period can create the "explosion" of infections.