First off, I know that in Asian grocery stores and so forth, many of the employees wear things like masks when giving out free sample, out of sanitary reasons. When the anthrax scare was around, many people in China wore masks to prevent themselves from getting it. Well in that case it's anthrax, and more of a big deal of course. In anime some people wear masks WHILE sick so they don't spread it to others (probably something we should really do too, but in our culture it's more of a dorky thing).
With simple colds though, I noticed in A LOT of anime, that the characters treat it like the person may die. I know, on the rare occasion people DO die from the common cold due to lack of immunities or whatever, but with our medicines and whatnot, it's never something to worry about. In fact, all the time people just don't care. "Yeah I have a cold, but I'm still going to school/work, whatever", but it's just shown as a VERY serious thing in anime where people like HAVE to stay home and all that. Yeah, I know you shouldn't take ALL your cultural facts from anime, such as say in comparison, saying that all Japanese are overly emotional etc etc. Still, I find at least the cold issue very common in most serious. In our culture it's like "Yeah I have a fever and it sucks" or "Oh that doesn't sound fun" :/ But over there it's like "OH NOES! THEY HAVE A FEVER!!! MAYBEDIEORSOMETHING?!?!" and the person is often depicted as being shown as REALLY sick and close to death. I've been through bad sick times when I was little, and fevers were more or less a nuisance with being extremely cold then hot, unlike in anime where the character just sits there in bed with a red face, panting (I'm sure everyone's seen that scene at least ONCE in an anime).
So, in the bottom line of it all, is it just a cultural difference that they seem moreso paranoid about colds that are probably not even fatal, and we just toughen it out and don't often worry too much on sanitary issues concerning the spread? Just... something I thought about^^