Not trying to be contrary here Rat but it was the polio vaccine that primarily put polio in the ash heap. Hygiene certainly played a part but less so in the US than other countries. Polio is spread 3 ways. Yes contact with contaminated poop is one, but is also spread between people by nasal and oral secretions. In the US spread was more likely by nasal and oral secretions than poop. Even in the 50's most everyone in the US had indoor plumbing and practiced decent hygiene. There is actually a theory by some scientists that improved hygiene may have at first led to an increased incidences of polio. It's a simple theory but I won't go into it here. Mass inoculations began in 1954 and by 1956 cases of polio dropped by 60 or 70% (I do not recall the exact % or number). Hygiene did play a part in reduction of the disease. The point I'm making is that it was primarily vaccinations that reduced the infection rate and ultimately eliminated it in the US.