What is polio?

Polio is a potentially fatal viral infection caused by a poliovirus. Also known as poliomyelitis, this infection is highly contagious and causes full or partial paralysis in the affected person. After entering the mouth or nose of a person, the virus reproduces in the throat or the intestine and spreads in the blood or lymphatic system. Once in the blood, it can reach the nervous system and attack the brain and spinal cord to cause paralysis.

What are the symptoms?

Symptoms take 1 to 2 weeks to appear after contracting the viral infections. People infected with poliovirus may be grouped in 3 categories:

  1. Asymptomatic patients: 95% of people infected with poliovirus may not show any symptoms; however, they may be a carrier of the virus and may spread it to others.
  2. Patients with minor (or non-paralytic) symptoms: About 4% of all poliovirus-infected persons show following minor and non-specific symptoms:
    – Fever
    – Headache
    – General discomfort
    – Tiredness
    – Nausea and vomiting
    – Sore throat
    – Flu-like symptoms
    – Stiff neck and back
    – Pain in the arms and calf muscles of the legs
    – Muscle spasms
  3. Patients with severe (or paralytic) symptoms: The severe effect of poliovirus is seen in less than 1% of all infected patients, who develop permanent paralysis of the legs (or less commonly, of the arms). If the virus also affects the respiratory muscles of people in this group, it can result in breathing difficulties and may lead to death. These patients may show additional symptoms like:
    – Abnormal sensations
    – Bloated abdomen
    – Difficulty breathing and swallowing
    – Constipation
    – Difficulty urinating
    – Drooling
    – Irritability
    – Muscle spasms, weakness and pain in the neck, calf, or back
    – Muscle weakness affecting one side of the body more

Respiratory complications and subsequent death is more common in elderly.

What causes polio?

Polio is caused by poliovirus, which affects only humans. Polio spreads from person to person mostly through fecal-oral route. However, a direct contact with the affected person or contact with polio virus-infected phlegm or mucus from the mouth or nose of the infected person may also spread the virus.

People, who are at higher risk of developing polio, may include:

  • People who are not immunized against poliovirus
  • People traveling to the areas of polio outbreak

Infected persons can carry the virus in their body for weeks and may spread the infection though the contaminated feces.

How is polio treated?

There is no cure for polio, but preventive vaccines are available.

Immunization against poliovirus is the most effective way to protect against this fatal and highly infective disease and provides immunity in more than 95% cases. Polio vaccines are administered from birth and are given at 2 months, 4 months, between 6 to 18 months and again in the form of a booster dose between 4 to 6 years of age. Vaccines are of two types:

  1. salk inactivated poliovirus vaccine (IPV), and
  2. sabin live-attenuated oral polio vaccine (OPV).

IPV is routinely used and is preferred to OPV, which caused paralysis in 1 per 2,000,000 vaccinated people. Adults are vaccinated with IPV only if traveling to areas with polio outbreak.

Supportive measures aim at providing relief from the symptoms. Such measures include bed rest, analgesics to control body pain, and anti-pyretics to control fever. Mechanical ventilation is given to people with breathing problems.


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