Causes of Polio
Polio is caused by infection with the poliovirus. This virus is highly contagious, and is passed on through food and water contaminated with the stool (feces) of infected people. It can take 4 to 21 days before symptoms appear and an infected person can pass the virus on to other people even before symptoms appear.
Infection with polio happens when the virus enters the body through the mouth, multiplies in the throat and intestine, and spreads through the blood to the central nervous system. There, the virus attacks nerve cells, which can lead to paralysis.