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. Because polio has no cure, vaccination is the best way to protect yourself and the only way to stop the disease from spreading. The spread of polio has never stopped in Afghanistan, Nigeria, and Pakistan. Poliovirus has been reintroduced and continues to spread in Syria, Cameroon and the Horn of Africa after the spread of the virus was previously stopped.
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 twentieth century. By 1979 the country became polio-free.