Polio - Symptoms
About 90 percent of those infected with poliovirus have mild or no symptoms. These symptoms include a low fever, fatigue, headache, sore throat, and nausea and vomiting. These symptoms usually last two or three days. People with these symptoms are still infectious and can pass the disease on to other people.
Another 10 percent of those infected with the virus experience more serious symptoms, including severe headache and pain and stiffness of the neck and back. The stiffness is caused when the tissues around the spinal cord and brain become inflamed. These symptoms usually disappear after several days. The patient usually experiences complete recovery.
People with polio often lose the ability to move their legs and/or arms. This disability is a terrible disaster. But it does not necessarily cause death. If polio also causes loss of control over the respiratory muscles, however, death can and often does occur. For polio patients, then, a device to help them breathe is an absolute necessity.
In 1982, the American physiologist Philip Drinker (1893–1977) invented the most famous of all devices for helping polio patients to breathe. The device was called the Drinker tank respirator. It is more commonly known as an iron lung.
The iron lung is an airtight cylindrical steel drum. It encloses the entire body with only the patient's head exposed. Pumps connected to the device lower and raise air pressure within the drum. As the drum contracts and expands, it forces the patient's chest to contract and expand also. The iron lung forces the patient's body to continue breathing.
Many polio patients were kept alive by the iron lung. They had to spend many years enclosed in the lung, with only short periods outside it. With the development of the Salk and Sabin vaccines, polio has nearly become extinct. As a result, the iron lung no longer finds much use in today's hospitals.
About 1 percent of people infected with the poliovirus develop the most serious symptoms of the disease. At first, they experience only mild symptoms. After a few days, however, the symptoms become much worse. They include severe headache and neck and back pain.
The worst effects of polio are caused when the virus invades motor nerves. Motor nerves are nerves that control the movement of muscles. The virus can destroy these nerves. As the nerves die, muscles lose their ability to move. They first become floppy and weak. Eventually they become paralyzed and lose the ability to move at all. After a few days, the muscles actually begin to decrease in size. The person does not lose the sense of touch in the affected areas, however.
The virus can also infect the brain stem. The brain stem is located at the base of the brain. It connects the brain to the spinal cord. A person may have trouble breathing and swallowing. In the severest cases, the heart rate and blood pressure may be disturbed. These changes can lead to the patient's death.
The maximum degree of paralysis usually occurs within a few days. After that time, some healthy nerves may try to take the place of the damaged nerves. This process lasts about six months. After that time, no further improvement is likely.
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