According to an individual on FaceBook who was responding to my "yay vaccines!" post, anyway. Apparently good nutrition, hygeine and less crowded living conditions were taking care of infectious diseases all on their own. I didn't read far enough into the article to get to the actual "self" portion of self-limiting because my tolerance for casual disdain for lives saved by vaccines is absolutely limited, but here's the link:
https://childhealthsafety.wordpress.com/graphs/ Edited to add:
Evil part of my brain: (endless giggling)
Me: I'm afraid to ask...
Evil part of my brain: The number of antivaxers old enough to be rolling the dice on shingles! (giggling resumes)