Poliomyelitis, or polio, is a viral infection caused by the poliovirus, a type of enterovirus. The illness can be mild or severe. In the worst cases it can cause paralysis and death. There have been no cases of wild (natural) polio acquired in the United States since 1979.
A person can get polio at any age, although infants and young children are most frequently affected.
Polio does not spread easily among people in highly vaccinated communities. When poliovirus spreads, it is usually within households, by the stool from an infected person; the virus can spread on hands or on objects. In unvaccinated people, it is also possible to spread the poliovirus through respiratory secretions.
In most cases, people infected with the poliovirus do not feel ill. Sometimes, poliovirus causes a flu-like syndrome with a few days of any combination of fever, malaise, drowsiness, headache, body aches, muscle pains, nausea, vomiting, diarrhea or constipation, and sore throat. In about 4 out of every 100 (4%) people with the infection, poliovirus causes meningitis, an infection of the coverings of the brain in less that one in every 100 people.
Symptoms usually appear 6-14 days after infection with the virus, but cases have been reported as early as 3 days and as late as 35 days after infection.
Polio is highly contagious. Only humans can get polio. Patients are most infectious from 7-10 days before to 7-10 days after the appearance of symptoms. However, patients can spread disease as long as virus is in the bowel movements or saliva. Virus may be found in the saliva of patients for approximately one week after symptoms appear and in bowel movements for 3 to 6 weeks.
There are three types of poliovirus. Infection with any one of these types leads to lifelong immunity to that type but not necessarily to the other types.
There are no specific medicines or antibiotics that are effective against the poliovirus. People who contract polio need medical attention to address the potential complications of the disease and for rehabilitation.
The most serious complication of polio is paralysis. Most commonly the legs are affected. Paralysis of the muscles used for breathing and swallowing can cause death.
Two types of polio vaccine are made: a live virus oral polio vaccine (OPV) and an inactivated virus injectable vaccine (IPV). The oral polio vaccine (OPV) is given as drops in the mouth. Very rarely, OPV can cause paralysis in a person who receives the vaccine or in a person who is a close household contact of the vaccinated person. This happens approximately once in every 2.6 million doses of OPV. To avoid this rare complication, OPV is no longer recommended for use as part of the routine vaccination schedule in the US and is currently not available.
Inactivated poliovirus vaccine (IPV) is a shot given in the leg or arm. IPV does not cause paralysis. IPV is not known to cause any reactions except mild soreness where the shot was given.
The recommended vaccine schedule for children is a total of four doses of IPV given at 2 and 4 months of age, between 6 and 18 months of age, and at 4 years of age.
The only effective control measure to prevent polio infection is maintaining the highest possible vaccination levels in the community.
For more information on where your child can be vaccinated, call 311 .
Last Updated: Decemeber 18, 2012