Diagnosis and Treament

Doctors diagnose polio by isolating the virus from an infected person using throat cultures, stool samples, or samples of fluids from the brain and spinal cord. Blood tests that indicate the presence of antibodies specific for the virus will also confirm a poliovirus infection.

As yet there is no cure for polio—no drug or other medical treatment can halt the destruction of poliovirus in the body. However, several medical treatments can lessen the severity of the disease. Mild cases of polio do not require specific treatment. For the more serious cases of paralytic polio, keeping patients still and quiet can, in some cases, minimize the severity of paralysis.

For these patients initial treatment consists of immediate hospitalization and strict bed rest. Simple treatments, including moist heat applied to affected muscles, can ease pain. Antispasmodic drugs can help patients who suffer involuntary muscle contractions as a consequence of nerve damage.

One of the most immediately dangerous complications of paralytic polio is loss of the ability to breathe. Such loss results from nerve damage that affects the muscles used in breathing or from damage in the area of the brain that controls breathing. In the early 1920s American physician Philip Drinker invented a mechanical device called an artificial respirator to treat patients at risk from this complication.

This device consisted of a large, airtight cylinder. Patients lay on their backs inside the cylinder with only their heads showing outside. Motors attached to the cylinder rhythmically changed the air pressure inside, forcing air in and out of the patients’ lungs. The machine soon acquired the nickname iron lung. For many people, the contraption summed up the worst fears of confinement and immobility associated with paralytic polio.

For countless patients, however, the iron lung provided lifesaving support until recovery and rehabilitation restored their ability to breath unaided. Today the iron lung has been replaced by a less cumbersome machine known as a ventilator. A ventilator forces air into the lungs by way of a tube inserted into the upper airway through the nose, mouth, or a slit in the trachea.

Once the high fever and other symptoms of polio’s most severe stage have passed, patients disabled by paralysis receive physical therapy. In the therapy sessions, therapists help patients stretch and move affected muscles.

This movement minimizes the atrophy, or shrinkage, of affected muscles and limbs and builds strength. Later, exercises may retrain muscles to compensate for other muscles that have been permanently paralyzed.

Patients may also undergo rehabilitative therapy to learn how to use braces, crutches, and other devices, which provide additional support and mobility.

Paralytic poliomyelitis may be clinically suspected in individuals experiencing acute onset of flaccid paralysis in one or more limbs with decreased or absent tendon reflexes in the affected limbs, that cannot be attributed to another apparent cause, and without sensory or cognitive loss.

A laboratory diagnosis is usually made based on recovery of poliovirus from a stool sample or a swab of the pharynx. Antibodies to poliovirus can be diagnostic, and are generally detected in the blood of infected patients early in the course of infection.

Analysis of the patient's cerebrospinal fluid (CSF), which is collected by a lumbar puncture ("spinal tap"), reveals an increased number of white blood cells (primarily lymphocytes) and a mildly elevated protein level. Detection of virus in the CSF is diagnostic of paralytic polio, but rarely occurs.

If poliovirus is isolated from a patient experiencing acute flaccid paralysis, it is further tested through oligonucleotide mapping (genetic fingerprinting), or more recently by PCR amplification, to determine whether it is "wild type" (that is, the virus encountered in nature) or "vaccine type" (derived from a strain of poliovirus used to produce polio vaccine).

It is important to determine the source of the virus because for each reported case of paralytic polio caused by wild poliovirus, it is estimated that another 200 to 3,000 contagious asymptomatic carriers exist.