Poliomyelitis, or Polio for short is primarily known for its paralysis in patients. Poliovirus can multiply in specialised cells in the intestines which enters the bloodstream to invade the Central Nervous System, where it spreads along nerve fibres and multiplies. The virus destroys nerve cells (Motor Neurons) which cannot regenerate. Consequently, nerve impulses are unable to be transmitted to skeletal muscles, causing paralysis.
Poliovirus also attacks the motor neurons of the brain stem, damaging breathing capacity and causing difficulty in swallowing and speaking. Without respiratory support, polio can result in death. Hence, many patients whose conditions were severe required a metallic cylinder infamously known as the “Iron Lung” for breathing support. The Iron Lung functions by creating a vacuum within itself. This air pressure in the Iron Lung will be reduced, relative to that of the atmosphere, forcing oxygen into the patient’s lungs.
Poliovirus is highly contagious. It is transmitted via oral contact with secretions or faecal material from an infected person. First outbreak of Poliovirus occurred in Vermont, USA 1894 with 132 cases. Fortunately, the onset of Oral Polio Vaccine (OPV) and Inactivated Polio Vaccine (IPV) have reduced the cases of poliomyelitis by over 99% as of 2003. Only 7 countries globally have any traceable poliovirus transmissions.
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