In 1979, the last wild case of polio was recorded in the U.S. However, In 1993, the virus was brought into the country by travelers with polio. Polio was once one of the most feared diseases in the U.S. The first outbreak, the U.S. experienced was in the late 1940s infecting the lives of thousands of citizens yet the number significantly decreased beyond the year 1955 after the introduction of inactivated Polio vaccine.

Since late 1979, no case of wild-type poliomyelitis was detected in the USA and until the year 1999, only 162 cases were identified with a rate of 6 cases per year. Most of the mentioned cases in that era were vaccine-associated paralytic poliomyelitis (VAPP) derived from the Sabin strain found in the oral poliovirus vaccine (OPV).

Polio is a highly contagious disease that spreads from person to person; a person can spread the virus even if they are healthy. Polio can enter the USA with just one traveller carrying the illness. Those most susceptible to infection include the non-vaccinated for polio, those who didn’t complete the recommended number of vaccinations and those going to places where they might be in danger of contracting polio.