Poliomyelitis, or polio, is a crippling and potentially deadly infectious disease caused by a virus that spreads from person to person invading the brain and spinal cord and causing paralysis, according to the Centers for Disease Control and Prevention. Cardinal George contracted the disease when he was 13. Because polio has no cure, vaccination is the best form of protection for individuals and the only way to stop the disease from spreading. The spread of polio has never stopped in Afghanistan, Nigeria and Pakistan, and it has been reintroduced and continues to spread in Chad and Horn of Africa.In the late 1940s to the early 1950s, in the United States alone, polio crippled around 35,000 people each year making it one of the most feared diseases of the 20th century.By 1979 the country became polio-free thanks to the vaccine developed by Dr. Jonas Salk and introduced in 1955. The eradication of polio from the Western hemisphere is among the most significant public health achievements of all time, according to the CDC.People who have had polio often go on to develop postpolio syndrome, which includes gradual weakening of muscles that were previously affected by the polio infection, muscle atrophy, pain and fatigue. The severity of symptoms varies from person to person, according to the National Institutes of Health.Cardinal George wrote in a Catholic New World column in August 2012 that he goes to the Mayo Clinic in Rochester, Minn, every five years so doctors could follow the after-effects of the polio. “As one of the doctors of the clinic told me when I was 35 years old and chair of the board of an Oblate-sponsored nursing home in Rochester, Minn.: ‘You have a stressful job, and you’re the first generation of polio patients who will grow old with the disease. You’re also the last, because of the effectiveness of the Salk vaccine. We’ll follow you until you get the disease that will kill you.’”