"How does polio spread?
Poliovirus is very contagious. The virus lives in an infected person’s throat and intestines. It spreads through contact with the feces (stool) of an infected person and through droplets from a sneeze or cough. You can get infected with polio if you have stool on your hands and you touch your mouth. Also, if you put objects, like toys, that have stool on them into your mouth, you/your baby can get infected.
An infected person may spread the virus to others immediately before and usually 1 to 2 weeks after developing symptoms.*The virus may live in an infected person’s feces for many weeks. It can contaminate food and water when people do not wash their hands."
http://www.cdc.gov/vaccines/vpd-vac/polio/fs-parents.html
It seems to me, the best way to avoid polio is to stay away from other peoples feces.
Now if I could just find the graph of polio infection going down for years, cut off that part, insert an arrow of the polio vaccine being introduced, and fail to mention the definition being changed at the same time, I could probably convince many that the magic shot saved the world.