The virus responsible for poliomyelitis, (often shortened to polio), usually enters the body through the throat.
From there it passes into the lymphatic and blood systems.
These systems transport it throughout the body.
It then enters the nervous system.
It spreads through the nervous system destroying the nerve cells, and can then infect the brain.
There are some early symptoms of polio which manifest themselves within a day or two of infection. These include:
mild headache, fever, sore throat
nausea, vomiting, diarrhoea
restlessness, drowsiness
Following this a fever develops slowly peaking after another couple of days. This rapidly subsides.
At this point the majority of polio sufferers recover.
In more severe cases the virus then attacks the central nervous system.
This leads to stiff joints, tender muscles and general pains.
Paralytic poliomyelitis forms of the virus then attack the motor nerves of the spinal cord.
Since these can not be regenerated this leads to a deterioration of muscle usage.
Partly damaged cells can recover their functionality so muscle usage may return to normal.
In some cases, the damage is sufficient to lead to paralysis, (mostly in the legs).
Other forms of poliomyelitis, (respiratory or bulbous), attack other areas of the spinal cord and/or brainstem.
These can lead to other muscle problems, usually related to breathing or swallowing and talking.
Polio vaccinations simply take the form of the virus itself.
Either a dead form of the virus is injected, or a live form is taken orally.
There are no effective drug-based treatments for polio.
Treatment usually takes the form of isolation, bed rest and careful watch.
About 80% of cases will recover.
Care is taken to exercise the muscles, (especially where signs of paralysis occur), to prevent deformities.
Help with breathing is also sometimes required during the worst stages of infection.
Repeat attacks of the same type of polio are rare, since the body will usually develop a life-long immunity to the virus.
(Sometimes there are strains different enough to cause a second attack.)
