I would be curious to learn if any studies are done in tropical places where cockroaches exist, everywhere, whether poverty is present or not.
I lived in Hawaii, and the fuckers are EVERYWHERE. No matter how clean you are able to keep the place. In brand newly built apartment buildings, they are there before the people move in.
I shudder to remember a single basement type apartment I moved into back when I lived in Hawaii in the 90s. The walls (looked nice, made of lava stones), had literal holes in them. The first time I started up the oven in that flat I swear, I thought I was being attacked by them, they (the big ones, they fly - we called them 747s) ended up getting killed by a broom and me screaming at my boyfriend to DO SOMETHING. We ended up with a huge dead pile of them. Freaking disgusting!
I know this has nothing to do with the medical aspects of this story, but I do know I've never seen a cockroach in any of the places that I have lived except Hawaii. I know there are a ton of them in Florida too, and probably throughout the south where it is so humid in the summers.