- Risk Factors
- Symptoms and Signs
- Polio is an infectious disease caused by polioviruses that can result in symptoms ranging from none to lifelong disability or death.
- Risk factors are highest for those people unvaccinated against polio, young children, immunosuppressed people, pregnant females, those people living or traveling in areas where polio is endemic, and polio patient caregivers.
- Polio symptoms first begin like any other viral illness; progressive symptoms include muscle discomfort and muscle paralysis with late symptoms of muscle atrophy, weakness, extremity disfigurement, and breathing problems in some patients.
- People who have risk factors or symptoms should seek medical care immediately.
- Diagnosis of polio is made by clinical observation of symptoms and by tests that detect the polio viruses in samples taken from the patient.
- There is no medical cure for polio; medical treatment is designed to reduce symptoms.
- There are many surgical methods used to help relieve symptoms of polio (mainly bone, joint, and muscle modifications).
- Follow-up is very important to help relieve symptoms and to be ready to treat post-polio syndrome if it develops.
- Prevention of polio is possible with appropriate vaccination treatments; avoiding contact with polio viruses by good hygiene and avoiding areas where polio is endemic also help prevent polio.
- The prognosis for most people who are infected by the polio viruses is good, but those few patients who develop paralytic polio have a prognosis ranging from good to poor, depending on the severity of infection and the healthcare they receive.
What Causes Polio?
Polio (also termed poliomyelitis or infantile paralysis) is an infectious disease caused by an enterovirus. The disease is characterized infection of the central nervous system that produces a wide range of symptoms from a mild nonparalytic infection to total paralysis that can happen over a few hours. There are three types or strains of polio virus; type 1 causes about 85% of all paralytic illness due to polio.
The history of polio infecting humans is long. A few Egyptian mummies from about 6000 to 1209 BC have been found with withered and deformed limbs that are probably due to polio. The first known written description of polio was in 1789, and the first described epidemic was described in 1834, although it is likely many outbreaks occurred before this date. Perhaps the most public figure who had polio was the U.S. president, Franklin D. Roosevelt. The viruses that cause polio were finally cultivated in tissue cultures in 1949. Affected individuals who were too weak to breathe were placed in an "iron lung" device that helped them breathe. Dr. Jonas Salk developed the first killed virus vaccine in 1954, and Dr. Sabin developed the live attenuated viral vaccine in 1958 (OPV or oral polio vaccine). In 2000, the U.S. switched to use of IVP shots (inactivated polio vaccine by injection); many other countries still use OPV. Polio vaccine development is a success story. The polio viruses survive in the wild only in humans and are transmitted only through human contact. It has been the goal of agencies like the World Health Organization (WHO) to eradicate polio worldwide. The efforts have led to a 99% decrease in polio infections worldwide with many countries reporting no new infections in years due to widespread vaccination programs. However, a few countries in Africa and the Middle East still see new infections. Developed countries see polio in the elderly or in immigrants. With ongoing vaccine efforts, the WHO still believes that, like smallpox, polio can be eradicated in the near future.
What Are the Risk Factors for Polio?
- The greatest risk for polio infection is not being vaccinated against the disease.
- Other risk factors include people with immunodeficiency (for example, HIV and cancer), very young individuals, pregnant females, people under extreme stress and exposed to polio, polio patient caregivers, lab personnel working with live polio viruses, and travel to areas where polio is still common.
Polio Vaccine and Prevention
Polio prevention is possible with vaccination; an appropriate vaccination series in young children can establish lifelong immunity to polio. For example, inactivated polio virus (IVP) is given at these intervals; 2,4, and between 6 and 18 months of age, with a booster shot between ages 4-6. Also, the CDC recommends people traveling to countries where polio is present get a polio booster shot before the travel.
Other prevention techniques involve avoidance of the viruses that cause polio. This is accomplished by avoiding the few areas where polio is still endemic and practicing strict hygiene, especially when caring for a polio patient.
What Are the Symptoms and Signs of Polio?
The vast majority of patients in the past and currently who have been infected with polio viruses show little or no symptoms and are unaware they have been infected. Patients who do show symptoms fall into two major groups, non-paralytic polio and paralytic polio. These groups are also termed minor (nonparalytic) and major (paralytic).
Non-paralytic polio, or abortive polio infections, involve the development of flu-like symptoms (fever, sore throat, headache, malaise, neck, and back and muscle stiffness or discomfort) that usually subside quickly (about 10 days with a few lasting a week or so longer) with complete resolution. Rare but potentially severe symptoms with complications can develop with paralytic polio. The initial symptoms mimic non-paralytic polio symptoms, but in about a week, paralytic symptoms of severe muscle aches and spasms, loss of reflexes, and flaccid paralysis (extremities are not controllable; they become floppy) develop. The paralysis may also occur suddenly and is sometimes worse on one side of the body. Breathing may become inhibited. Paralytic polio includes all forms of polio viruses that infect the central nervous system.
When Should I Call a Doctor about Polio?
Any person who has had any of the risk factors listed above, especially unvaccinated children or adults who may have had an exposure to a patient with polio or recently traveled in a polio endemic area, should seek medical care.
How Is Polio Diagnosed?
A doctor may make a preliminary diagnosis of polio from a patient's lack of vaccination, likely contact with the polio viruses, and symptoms of muscle aches, stiffness, and difficulty with limb movements and breathing or swallowing. Definitive diagnosis is done by obtaining samples of throat mucus, stool samples, and /or cerebrospinal fluid. Laboratory tests can detect the viruses in these samples for a definitive diagnosis, and other tests can detect if the person is making antibodies against polio viruses.
What Is the Medical Treatment for Polio?
There is no treatment that will cure polio once the virus has infected the patient. The key to treatment is early diagnosis and supportive treatments such as bed rest, pain control, good nutrition, and especially physical therapy to prevent deformities from occurring over time and prevention of muscle function loss. Some patients will need extensive support such as breathing assistance and special diets if they cannot swallow or have difficulty swallowing; others may require splints to avoid pain, muscle spasms, and limb deformities.
Is Surgery a Treatment for Polio?
There is an extensive body of literature that describes the various surgical techniques that have been used to treat polio patients. Most polio patients who undergo surgery have either not had treatment or failed medical treatments and are often in the residual or post-polio syndrome stage (see prognosis section below). Such a discussion is too lengthy to present in this article, but the surgical topics listed below can give readers insight into the long-term complications that may result from paralytic polio and why vaccination that prevents the disease is so important:
- Contracture release surgery
- Muscle transplantation
- Joint stabilization, joint fusion, and joint replacement surgery
- Limb lengthening
- Foot correction surgery
What Is the Follow-up for Polio?
Follow-up of patients with polio, especially those who develop the paralytic disease is often lifelong and remains the best way to reduce complications and treat the disease symptoms. Depending on the severity of the disease symptoms, follow-up care may range from physical therapy to multiple surgical interventions.
A major reason for follow-up is to monitor the patient for post-polio syndrome. Post-polio syndrome is a condition of increasing muscle weakness, muscle pain, and fatigue that can appear about 15-30 years after recovery from the initial paralytic disease. It may occur in 25%-50% of patients who develop paralytic polio. Treatment of symptoms is supportive (rest, braces, and pain control).
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Centers for Disease Control
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