Poliomyelitis - also called polio and infantile paralysis - is an acute communicable disease caused by the poliovirus. Most patients present with minor illness (fever, malaise, headache, sore throat, and vomiting), but a few develop aseptic meningitis and paralytic illness.
In the United States, only 5 to 10 cases of the disease are reported annually. These cases are associated with the use of oral poliovirus vaccine, with infants frequently developing signs and symptoms after the first dose of the vaccine. Most of the other cases develop in individuals who haven't received vaccines and are in close contact with infected individuals.
Polio is caused by a picornavirus. This is one of a group of viruses known as the enteroviruses, because they inhabit the intestine. These viruses are passed out in the stools in large numbers for up to six weeks after the start of the illness.
The front pole cells of the spinal cord are concerned with the nerves to the voluntary muscles (motor nerves), and it is these cells that are affected, causing paralysis that may be extensive. Myelitis means inflammation of the spinal cord. This is why the full name of the disease is anterior poliomyelitis.
Symptoms and Signs
Isolation of the poliovirus from throat washings early in the disease and from stools throughout the disease confirms the diagnosis. If the patient has a central nervous system infection, cerebrospinal fluid cultures may aid diagnosis. Coxsackievirus and echovirus infections must be ruled out. Convalescent serum antibody titers four times greater than acute titers support a diagnosis of poliomyelitis.
Poliomyelitis calls for supportive treatment, including analgesics to ease headache, back pain, and leg spasms. Morphine is contraindicated because of the danger of additional respiratory depression. Moist heat applications also may reduce muscle spasm and pain.
Bed rest is necessary until extreme discomfort subsides. It also helps prevent increased paralysis. Patients with paralytic polio may be bedridden for a long time and then require long-term rehabilitation using physical therapy, braces, and corrective shoes. Orthopedic surgery also may be necessary.
Bladder involvement may require catheterization, and respiratory muscle involvement may require mechanical ventilation. Postural drainage and suction may be sufficient to manage pooling of secretions in patients with nonparalytic polio.
Polio immunization (vaccine) effectively prevents poliomyelitis in most people.
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