Actually, AIDS is most common among uneducated people in the 3rd world countries, but that's beside the point.
It's true though that AIDS is very wide spread among gay (male) popularity. But that doesn't mean everyone who's gay will automatically come into contact with it one day. It's also a (very sad) fact though that many people seem to believe that.
In the 80's (I think) when knowledge about the desease was still sparse it was even referred to as the "gay-fever". That shows how prejudice works its way through society, even though nowadays children are being taught about it they still grow up saying "I'm not in any danger, I don't f*** a**"
It's tragic, really.