Hiv doesn't last long in air, if I remember correctly. Colds and flu, I assume so, if one exits one's balloon for a bit; mrsa Staph, sure, check out the locker room. Salmonella, usually via the digestive system, but I suppose so if you fondle uncooked contaminated food and then suck your thumb. Plague, I don't remember. Thought that was transmitted via a bite, but I'm easily wrong on that.
Hey, I bet I'm one of the few here who has had scarlet fever. It was traced to a job I was assigned (some sort of thing between my parents and the school administration, must have some "good for her" aspect) of cleaning the kindergarten room after school. Yep, a child there had had it. Strep throat, wild fever, rash like crazy, two week quarantine, thus, radio programs - I was 12 then. Lucky it didn't go into heart complications.) I haven't heard about it much in the last decades, might be less of a problem now than in the fifties - or maybe I haven't read the right articles.