This virus causes paralytic poliomyelitis, which means inflammation of the spinal cord. It has since been a relic of the past because of vaccinations. There are currently about 100,000 cases and 10,000 deaths every year around the world, mostly in Asia and Africa.
The virus comes in three distinct types and are the most dangerous of the enterovirus group. They are very simple, consisting of only a single strand of 12 genes, which target the host's nerve cell. It has been around since ancient times.
It first gained attention after an epidemic hit the U.S. summer of 1916. Like other enteroviruses, it likes to inhabit the alimentary canal. Only 1% of the cases actually shows symptoms. Before the vaccine, there used to be about 21,000 cases of polio out of a population of 150 million a year in the U.S. That's unusually low for such a contagious disease. As a result, it was a great mystery as to how this disease spread until it was discovered in 1940. It also explained why quarantines were ineffective in containing the disease.
Polio is a funny disease. It was initially thought to only strike rich countries with good sanitation. Traditionally you associate the poor with the disease. However, paralysis in poor equatorial countries were so rare compared to countries like the U.S. The reason for this is the fact that people can become naturally immune at an early age when it's less likely to cause a serious problem. Thus, it scared the industrial world predominately.
The prime age for getting this disease in the 1950s in the U.S. was ages 5 to 9. 2/3 of the victims over 15.
There used to be controversy over whether to use the injected Salk vaccine which consisted of dead viruses developed in 1956 or the oral Sabin vaccine which was made from attenuated live viruses in 1960. Now, we use the cheaper oral vaccine. The killed virus vaccine has not been made since the 1965 in the U.S.
There were only four cases of polio in the U.S. in 1985. Since the live vaccine could mutate into a more deadly form, it is not given to people with an impaired immune system.
Since 1988, the World Health Organization (WHO) has wanted to wipe out the disease by the end of the century. By the end of 1991, it was only found in eight children in this half of the planet. Person to person transmission is confined to Peru. Since then, zero people have been infected.
Of the countries where there is still polio, 42% of the cases in 1993 were in India, 19% in Pakistan, and 15% in Africa.
It is famous for striking prominent people like FDR.