Polio is a highly contagious picornavirus, though only a few patients develop any illness from the infection.
Spread: Droplet or faecal-oral.
Incubation: 7 days.
Signs: Flu prodrome for 48h then pre-paralytic stage: T°, pulse, headache, vomiting, neck stiffness and unilateral tremor. In <50% this progresses to a paralytic stage: myalgia, LMN signs ± respiratory failure. No sensory signs.
Natural history: <10% of those with paralysis die. There maybe delayed progression of paralysis (post-polio syndrome, PPS). Risk of severe paralysis in adults; pregnant; muscle fatigue/trauma during incubation period. PPS causes fatigue, weakness, myalgia, and worsening function, not necessarily at sites originally affected (advise enough exercise to prevent wasting but no so at sites originally affected (advise enough exersice to prevent wasting but not so much as to weaknessin aldready damaged muscles)). No drug works.