Poliomyelitis, commonly called polio, is a viral infection. The virus enters through the mouth, multiplies in the intestines to finally tackle the spinal cord. The virus destroys nerve cells (motor neurons) that control muscles. The cells controlling the sensory and sexual functions are not affected.
The infection is contagious. The virus is transmitted by the spit of an infected person or drinking contaminated water. The first symptoms resemble the flu and the virus is usually eliminated by the immune system. The patient may experience a stiff neck and muscle pain.
In 1% of cases, the virus manages to attack the nerve cells and, to a certain point, up to 95% of motor neurons may be affected. After this acute phase, the patient recovers, but may retain 10% of sequelae. In 10% of cases, the infection is fatal. In several cases, polio causes irreversible muscle atrophy.
Some patients are placed in iron lungs to enable them to breathe artificially.
There is no cure for polio. Vaccination is the only effective defense. In Canada, the two vaccines are approved vaccine Salk which is three shots in less than twelve months and the Sabin vaccine that is taken (three doses) orally. The Salk vaccine offers great protection but does not protect you for life. The Sabin vaccine would produce side effects in some cases.
At the end of the twentieth century, polio cases have decreased 95% worldwide, but there is an increase of cases in 2004. The disease is still problematic in some thirty countries in Africa and Asia.
In Canada, the last epidemic occurred in 1959 and the last case of polio in the country was reported in 1977. Isolated cases of polio occur in communities where vaccine is refused for religious reasons.
Post-polio syndrome
Approximately 50% of polio survivors may experience severe fatigue and joint pain after more than thirty years without symptoms. This phenomenon is called post-polio syndrome. Survivors may also experience progressive muscle weakness and sometimes breathing difficulties. Some have difficulty concentrating and memory problems.
The symptoms attributed to post-polio syndrome are not easy to assess. Some symptoms are interwoven with symptoms caused by the patient's age.
29 avril 2010
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