Poliovirus, pictured in this colored transmission electron micrograph, is transmitted via direct person-to-person contact with infected mucus, phlegm or feces. Symptoms can include fever; fatigue; muscle pain or weakness; stiff neck and back; and difficulty swallowing or breathing. It is important to remember that many people with polio are asymptomatic, but can still spread the virus to others.
Poliomyelitis involves the central nervous system, causing inflammation and cell death that can lead to deformity and paralysis in about 1% of patients. Patients with paralytic polio might have difficulty lifting the head or lifting the legs when lying flat on the back, and their reflexes might be abnormal. This patient, photographed in Africa, has kyphosis and scoliosis; spinal deformities caused by the virus.
Today many U.S. parents feel more threatened by rare vaccine complications, than the illnesses vaccines prevent because they have never seen the effects of the disease.This historic photo shows children with paralytic polio wearing calipers on their legs for support, while participating in physiotherapy.
In 1957 Albert Sabin developed the oral poliovirus vaccine (OPV), which was subsequently used in mass immunization programs that were successful in eradicating polio in the U.S. and Europe. This photo from 1962, shows people in Austin, Texas, lining up to receive the vaccine.
About 10% to 15% of patients who develop paralytic polio experience lung involvement, which often leads to death. Before widespread vaccination, a device called a negative pressure ventilator or “iron lung,” pictured above, was used to help polio patients breathe.
Although OPV use was discontinued in the U.S. in 1995, the vaccine is still being used in immunization campaigns, like this one in Gorakhpur, India in 2000. Due the success of these efforts, India has reported just one case of wild poliovirus type 1 in 2011. Polio transmission continues to occur in parts of Africa, Afghanistan and Pakistan.
Children are considered immunized against poliovirus once they’ve received four doses of either OPV, IPV or some combination of both, with the first dose administered at age 2 months, the second dose at age 4 months, a third dose at ages 6 to 18 months and a booster dose administered at ages 4 to 6 years.
Poliomyelitis is a viral disease that can lead to partial or full paralysis. Before the introduction of the Salk inactivated polio vaccine (IPV) in 1955, polio was a worldwide epidemic, with more than 20,000 cases reported in the United States each year. Due to the success of the vaccine, by 1965 there were only 61 reported cases of paralytic polio. Although polio disease is considered eradicated in the United States, unvaccinated individuals are at still at risk for contracting poliovirus imported to the U.S. from areas of the world where it is still endemic. Between 1980 and 1999, the CDC confirmed 162 cases of paralytic polio in the U.S., eight of which were imported or acquired outside of the country, and 154 of which were caused by live oral polio vaccine – a vaccine formulation discontinued in the U.S. in 1995. Because polio is no longer a common illness in many Western countries, public health officials warn that clinicians and parents may not be able to recognize the disease. They advise clinicians to suspect poliomyelitis in any child with acute flaccid paralysis that has traveled to areas of the world where poliovirus is still being transmitted. View the slideshow below to learn more about signs and symptoms of polio, as well as the history of the illness.