Polio also known as poliomyelitis, is a virus that enters the brain and spinal cord through the blood. It invades the nervous system and can cause paralysis. Only 0.1% of people have suffered paralysis from poliovirus infection, but unfortunately there is currently no cure. It also can lead to death due to breathing difficulty.
The virus enters the body through the mouth and spreads throughout the intestines. It can be transmitted by the fecal-oral route. Infants are at the most danger of polio infection.
More than 90% of people infected are completely asymptomatic (subclinical infection).
Even if symptoms appear, symptoms usually surface 5 days after the infection and symptoms are similar to the summer cold. At this stage polio symptoms can range from mild fever, overall discomfort, headache, drowsiness and soreness. If such symptoms develop it is important to rest.
When summer cold symptoms worsen, meningitis symptoms accompanied by fever / nausea, vomiting, neck stiffness, strong headache may occur. Around 4 to 8% of infected people experience these symptoms
When poliovirus reaches the anterior horn cells of the spinal cord, it causes motor paralysis (paralytic polio). When the central nervous system such as cranial nerve and medulla oblongata become infected respiration becomes difficult and breathing becomes difficult and will lead to death.
Currently there are no polio naturally occurring cases in Japan, but the possibility of the introduction to the bacteria from overseas still remain, and possibly getting infected remain. Vaccination is recommended for people going overseas or working internationally.