Polio is a very serious disease, which can lead to paralysis or even death. With widespread use of vaccine, the disease has been eliminated from the Americas. Today, polio mainly occurs among unimmunized individuals, or those with weakened immune systems in contact with other individuals who are receiving the oral polio vaccine. As oral polio vaccines are phased out and replaced with injectable polio vaccine, we will no longer see cases of vaccine-associated polio. In the developing world, the virus is spread by eating food or drinking water contaminated by the virus and direct contact with infected stool or throat secretions.
People are most infectious a few days before and after the onset of symptoms.
The milder forms of polio usually come on suddenly and last only a few days. Some people who have the disease may not feel ill at all. Some mild symptoms include a fever, sore throat, upset stomach, headache, or stomachache. Sometimes one will feel pain and stiffness in the neck, back, and legs. Even if an infected individual does not have symptoms, people with polio can still pass it on to others.