Thats it, good health care, clean food and clean water. Oh yeah and a rediculosely overzealos market for home cleaning products that have gone above and beyond the actual need for home sanitation.

One of the most interesting cases of this is Poliomyelitis (polio) which used to never be a crippling disease. Infants would usually contract it during the first few years and the disease was limited to a dirrheal disorder. It wasn't untill the turn of the century when stuff like chlorox became available in middle and upper middle class homes as a sanitizer that babies no longer contracted the disease as was normal. The older a peson gets the more likely polio is to cause paralysis. It's pretty devestating between the early teens and late 20's, look at FDR and any stock Iron lung photo's.