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Poliomyelitis - Incubation And Natural Immunity, The Iron Lung, World Eradication Of Polio, Feasibility For Eradication

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There are three viruses responsible for the infectious disease now called poliomyelitis. It has been called infantile paralysis and is now commonly referred to as polio. While the disease usually afflicts young children, adults can succumb to it also.

A notable example of polio in an adult was the case of President Franklin Delano Roosevelt, the thirty-second president of the United States. He contracted poliomyelitis at the age of 40. While he was able to return to health through an intense effort of physical therapy, he lost the use of his legs. As the President of the United States he used canes and orthotic devices to stand when he appeared before audiences in the 1930s and 40s. Although he was bound to a wheelchair, to most people he was able to convey the illusion that he was still able to walk.

Infection from poliomyelitis is spread through infectious contact with someone who already has the disease or as a result of poor sanitation where human waste products infect others. The mouth is the usual pathway of the virus which then enters the blood system. Paralysis mostly to the arms and legs occurs from lesions to the central nervous system. These lesions occur when the polio viruses begin to invade the central nervous system.

Clinical reactions to the polio viruses can range from none to symptoms that are mild ones which resemble the common cold (headache, sore throat, slight fever). These symptoms can vanish in a short period of time, anywhere from one to three days. A major illness of polio can be defined when the viruses attack the central nervous system, and even in these cases about 50% of the patients will fully recover. Of the remaining 50% about half of those will retain some mildly disabling after-effects, while the other one-half will show signs of permanent disability. Special devices may have to be used in these cases, such as an iron lung to assist in breathing when the respiratory system is impaired by the disease.

A form of the disease that can be fatal is the kind that leads to a paralysis of the muscles in the throat. This type of paralysis can lead to the regurgitation of the gastric juices into the respiratory system thus causing it to shut down. The large majority of these cases (80%) can still recover through proper treatment. This complication of the disease is known as bulbar poliomyelitis.

Because infants in underdeveloped parts of the world may have built up immunity from their mothers who had been exposed to the virus, there has been a belief that these children were less at risk of contracting polio than children in advanced countries with improved sanitation. Demographic statistics of incident rates, however, tend to raise questions about the effectiveness of natural, infant immunities developing in backward countries. Immunization programs against poliomyelitis as well as other common childhood diseases is still carried on by the World Health Organization as the only reliable way of eradicating the disease.

In the 1950s two types of vaccines were developed in the United States. One type, the Salk vaccine, named after its developer Jonas Salk, used dead polio viruses that were injected. The other type is called the Sabin vaccine, after Albert Sabin, and is an oral vaccine using a weaker strain of the polio viruses for immunity.

Since both vaccines are effective against all three strains of the polio viruses, there has been a virtual eradication of the disease in the United States and other countries that are able to employ a successful immunization program for their populations.

For those who contracted the disease before the vaccination programs became fully effective there have been reports of a disorder which is referred to as post-polio syndrome. This condition is characterized by fatigue, pains in the joints and muscles, problems with breathing, and a loss of muscle strength. Physical and occupational treatment therapies have been developed to deal with this problem.


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