What is Polio?
Polio is a contagious viral illness that in its most severe form causes paralysis, difficulty breathing and sometimes death.
In the U.S., the last case of naturally occurring polio happened in 1979. Today, despite a concerted global eradication campaign, poliovirus continues to affect children and adults in Afghanistan, Pakistan and some African countries.
The Centers for Disease Control and Prevention (CDC) advises taking precautions to protect against polio if you’re traveling anywhere there’s a risk of polio.
Signs and Symptoms
Polio is a viral illness that, in about 95% of cases, actually produces no symptoms at all (called asymptomatic polio). In the 4% to 8% of cases in which there are symptoms (called symptomatic polio), the illness appears in three forms:
- a mild form called abortive polio (most people with this type may not even suspect they have it because their sickness is limited to mild flu-like symptoms such as mild upper respiratory infection, diarrhea, fever, sore throat, and a general feeling of being ill)
- a more serious form associated with aseptic meningitis called nonparalytic polio (1%-5% show neurological symptoms such as sensitivity to light and neck stiffness)
- a severe, debilitating form called paralytic polio (this occurs in 0.1%-2% of cases)
People who have abortive polio or nonparalytic polio usually make a full recovery. However, paralytic polio, as its name implies, causes muscle paralysis and can even result in death.
In paralytic polio, the virus leaves the intestinal tract and enters the bloodstream, attacking the nerves (in abortive or asymptomatic polio, the virus usually doesn’t get past the intestinal tract). The virus may affect the nerves governing the muscles in the limbs and the muscles necessary for breathing, causing respiratory difficulty and paralysis of the arms and legs.
Who is at risk?
Polio can strike at any age, but it mainly affects children under five years old.
Risk factors for Paralysis
No one knows why only a small percentage of infections lead to paralysis. Several key risk factors have been identified as increasing the likelihood of paralysis in a person infected with polio. These include:
- immune deficiency
- removal of the tonsils (tonsillectomy)
- intramuscular injections, e.g. medications
- strenuous exercise
Treatment and Prevention
There is no cure for polio, only treatment to alleviate the symptoms. Heat and physical therapy is used to stimulate the muscles and antispasmodic drugs are given to relax the muscles. While this can improve mobility, it cannot reverse permanent polio paralysis.
Polio can be prevented through immunization. Polio vaccine, given multiple times, almost always protects a child for life.