Polio is a viral infection that primarily affects the nervous system and can cause a range of effects on the body. Most people with polio have no symptoms or mild flu-like symptoms such as fever, sore throat, headache, and muscle aches. However, in some cases, the virus invades the central nervous system and leads to more severe outcomes including meningitis and paralysis. Paralytic polio occurs in about 1% of infections and causes muscle weakness that rapidly progresses to paralysis, usually affecting the legs but sometimes the muscles for breathing and swallowing, which can be life-threatening. The paralysis causes muscles to become weak, floppy, and poorly controlled, often leading to permanent disability or death if breathing muscles are affected. Polio can also cause late effects years after recovery, like new muscle weakness and fatigue due to damage to motor neurons.
How Polio Affects the Body
- Initially may cause mild symptoms or be asymptomatic in most cases.
- In about 1%, the virus enters the nervous system causing headaches, neck stiffness, and meningitis.
- Paralytic polio destroys motor neurons in the spinal cord and brain stem, resulting in muscle weakness and acute flaccid paralysis.
- Paralysis can be asymmetrical and affect limbs, the diaphragm, or muscles involved in swallowing and breathing.
- Death occurs in 2-10% of paralytic cases due to respiratory failure.
- Long-term effects may include post-polio syndrome with muscle pain and new weakness years later.
Polio is highly infectious but preventable by vaccination, and while there is no cure, the vaccine protects against these severe effects.