Everybody who goes to conventions, especially conventions for hobbies, SF, fantasy, mystery, gaming or media interests knows what con crud is. It's a type of cold or flu-like disorder that many people come down with either at those conventions or just after. Not everybody gets it, of course, and few people get it every time, but as long as there are a few people there who are in the contagious stage, it's going to be passed around. I've been lucky, so far, because in several decades of attending SF and media cons I've never come down with it. I also try to make sure that I get adequate sleep while I'm enjoying the con and that just might be why I've been immune to it. Remember, if you want to come home healthy, don't insist on partying all night, every night and be sure to eat at least one healthy meal every day.