Polio is also called as poliomyelitis or infantile paralysis. Polio is a viral infectious disease, contagious in nature. The highly infectious virus, polio virus causes polio the historically devastating disease. Polio has been eliminated from western countries during the later period of 20th century.
The word polio is derived from Greek word polio which means grey and myelin which means spinal cord. so the meaning of poliomyelitis is infection of grey matter of spinal cord. usually 90 % of polio affected individuals does not show any symptoms. Affected individuals shows some symptoms after the polio virus enters the blood stream. Only one percent of effectively infected individuals with polio virus shows the flaccid paralysis, after the central nervous system or spinal cord is affected.
Causes of Polio
Member of the genus enterovirus, POLIO virus causes POLIO. Polio virus is a RNA virus inhabited in the human intestine and infects only the human beings.Three serotypes of polio virus are present type 1, type 2, and type 3. All the three serotypes are covered with capsid protein and all are extremely virulent. Type 1 polio virus is most commonly infecting the human beings and leads to paralysis. Till the vaccination for polio was invented in 1955, the polio affected millions of children world wide.
Polio can infect human beings at any age but, children are most infected as the immunity is not completely developed.
Effective vaccination against polio was invented in 1955 and due to vaccination, polio was eliminated from USA in the year 1979 and from the western hemisphere in 1991.
Signs and symptoms of polio
Nearly 90 % individuals infected with polio virus shows no symptoms and polio infection becomes Asymptomatic. Only 4 to 8 % of infected with polio virus shows the following symptoms.
Abortive polio : is the mild form of polio infection, and the individuals nervous system is not affected. Polio infected individuals shows mild symptoms such as flu like fever, upper respiratory tract infection, diarrhea, sore throat , etc..
Non paralytic Polio : is a serious form of polio infection, leads to aseptic meningitis. The symptoms such as sensitivity to light, heaviness of head are common with this type of polio infection.
Paralytic polio : is a severe debilitating form of polio, leads to paralysis. Only 0.1 to 1.8 % of human are affected with this type polio infection and severe mobility problems and neurological problems are observed.
People with abortive polio and/or non-paralytic polio recovers fast from polio infection. In case of paralytic polio, the polio virus enters blood stream from intestinal tract, and infects nervous system. When the nervous system is affected muscles becomes paralysed and even the severe polio virus infection may lead to Death.