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Polio, actually three different viral strains, enters the body through the nose or mouth and travels to the intestines where it incubates. Within a few days, patients experience flu-like symptoms including headaches, nausea, vomiting, and fever. It is at this stage that they become contagious. The virus can be spread through droplets traveling through the air and deposited in food and water.

Typically, the body will create antibodies to fight the virus, but 10% of victims develop symptoms, with 1% developing a paralytic form of polio. The paralytic form of the virus was the most dramatic and damning for its victims. Striking at the nerves in the brain, the virus would paralyze limbs or, in some unfortunate cases, the lungs. The image of a cumbersome metal breathing container, an "iron lung," is what many people still associate with the disease.  The dreadful-looking contraption enabled those with lung paralysis to breathe despite the failure of the body to expand and contract the lungs on its own.

Oddly, the strides made in hygiene at the early part of the last century contributed to the spread of the virus. Before that time, infants were typically exposed to the virus and used the mother's antibodies from breastmilk to build up their own immunities. The cleaner environments and fewer breastfed babies in more modern times allowed polio viruses to attack young children who had not received any polio antibodies or exposure early enough in life to have the mother's antibodies assist them in fighting the infection.

Through Roosevelt's development and support of the March of Dimes, a cure for polio was sought for decades. In 1947, a young Dr. Jonas Salk, an immunologist at the University of Pittsburgh, began his research on poliovirus.

By 1949, he had developed a method of growing poliovirus in cell cultures, instead of having to use monkeys for research. But he still needed to find a way to process the viruses so that they were less infectious before he could use them in an effective vaccine.

1952, Salk finally developed a vaccine using a mixture of the three types of poliovirus grown in monkey kidney cultures. He developed the process using formalin a chemical that inactivated the entire virus.

Large-scale testing of the vaccine began in the US and Canada in 1954, and by 1955, the governments of both countries granted permission for the distribution of the immunizations to school-age children.

The outbreaks of polio dropped dramatically thereafter. With the goal of Salk and his team being the eradication of poliovirus by 2000, it would appear, with minor third world exceptions, that they were wholly successful.