Post-Polio Syndrome is not a viral disease since polio virus that initiated the disease is gone. Polio infection destructs cells of the anterior horns in the spinal cord that pass on impulses from the brain to the muscles. The surviving neurons of the anterior horns are therefore more sparsely distributed than before. The assumed natural specific clone inhibitor may than inhibit the remaining nerve cells more than before. This inhibition may accumulate and increase the paretic symptoms even though the virus is gone long time ago. This may also explain why women with greater cell mosaic are more exposed.