For most of human history, polio was a rare disease. It was called infantile paralysis because it mainly attacked very young children, causing lifelong severe weakness of the muscles in the legs or the arms. The Scottish poet and novelist, Sir Walter Scott, was most likely one of those rare cases. In 1773, at 18 months of age, he had a fever that lasted 3 days and resulted in paralysis of one leg. Polio also has a more sinister side. In a small proportion of cases, the muscles that control breathing are so seriously impaired that the patient dies [1, 2].