Post-polio syndrome (PPS, poliomyelitis sequelae) is a group of latent symptoms of poliomyelitis (polio), occurring at about a 25 to 40% rate (latest data greater than 80%). It is a viral infection of the nervous system after the initial infection.[citation needed] Symptoms typically occur 15 to 30 years after an initial acute paralytic attack. Symptoms include decreasing muscular function or acute weakness with pain and fatigue. The same symptoms may also occur years after a nonparalytic polio (NPP) infection.

Source : Wikipedia

The causes of PPS have been investigated for around 100 years, but as yet none of the theories regarding its mechanism has been generally accepted as an explanation. The most prevalent is the 'Neural Fatigue' theory - which suggests that neurons which have remained intact after a polio infection are under increased strain, and the natural ageing process cause them to gradually fail.

Also see ; Poliomyelitisplugin-autotooltip__plain plugin-autotooltip_bigPoliomyelitis

"Nearly 100 years after its discovery poliovirus remains one of most thoroughly studied and best understood virus models for the molecular virologist. While poliovirus has been of vital importance for our insight into picornavirus biology at the cellular and biochemical level, it is ironic to note that, due to the early success in defeating poliomyelitis in the developed world through vaccination,