A highly contagious disease, polio is caused by infection with poliovirus, a virus that only infects humans. How is it spread? Poliovirus is most often spread through contact with stool of this infected person (known as fecal-oral transmission). Transmission can also occur through contact with infected respiratory secretions or saliva, though this is less common.
Most people who are infected with poliovirus have no symptoms; however, they can still spread the virus. Currently, no treatments exist to kill the poliovirus. Antibiotics or other medications are not effective because polio is caused by a virus. Therefore, treatment focuses on providing relief of symptoms as the body fights the poliovirus.
Thanks to the introduction of the Salk vaccine in 1955, polio is now considered a rare disease.
(For more information on this disease, click Polio. This full-length article discusses the incubation period, prognosis, why polio is sometimes mistaken for other medical conditions, and more.)