I don't know about most of them, but there's something you really must watch for.
It's not a virus, nor a bacterium. Might be a prion or sumfin.
It's called the ghey.
You can get it from looking at people with it sometimes, though rarely. Talking to the people with the ghey will trasmit it directly. Even saying words like "super" the wrong way can give you the ghey. Decorating your house will give it to you. Dressing well, and smelling good will give it to you. If you ever admit to more than 6 people at once that you don't like football, instant ghey.