I'm reading a book called the Moth in the Iron Lung. It's about the history of polio and the confusion and bullshit surrounding it. The polio virus has been around a long time and wasn't much of a problem. It would result in paralysis if and only if it got into the spinal cord where it caused lesions and destroyed the motor nerves. Often times this started and stopped with the lower spinal cord, resulting in leg paralysis. The increase in problems started with an insecticide called Paris green that contained arsenic. This was later replaced by a stickier creation called lead arsenate that contained lead in addition to arsenic. Many people who allegedly had polio were actually poisoned by lead and arsenic on fruit and vegetables. Many cases labelled polio featured convulsions that are not a symptom of the poliovirus affecting the spine. They are indeed symptoms of arsenic and lead poisoning. Lead and arsenic can also cause paralysis, and they are most likely what got to president Roosevelt. Generally, if the poliovirus caused paralysis, it happened in childhood. Roosevelt became paralyzed in adulthood. Following WWI there was the idea of using war planes as crop dusters. This resulted in an expansion of the use of lead arsenate into areas that previously had not used it. This resulted in an increase in childhood paralysis attributed to the poliovirus. I haven't gotten to the part where vaccines were rolled out.