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Poliomyelitis is a crippling, viral, infectious disease, which affects the central nervous system causing paralysis. It occurs round the year but more commonly in summer & monsoon.

Sex or Age most Affected

In India, polio is essentially a disease of infancy and childhood. About half of reported cases are below 1 yr of age, 6 months to 3 years being the most vulnerable age. The ratio of Boys to Girls, affected, is 3:1.

Signs & Symptons

When an unimmunized child, is exposed to poliovirus, he may respond in one of the following ways-

  • mild illness
  • non paralytic poliomyelitis (aseptic meningitis), or
  • paralytic poliomyelitis
  • inapparent infection without symptoms

As the disease progresses, one response may merge with the next severe form. Only about 1% of poliovirus infections result in paralysis.

The paralysis of polio is classically of asymmetrical and unequal distribution. If Respiratory muscles are affected it can be life threatening and is usually the cause of death. After the acute phase, atrophy of the affected muscle leads to a life with residual paralysis, which is typical and relatively easy to identify as poliomyelitis.



The poliovirus is normally present in the intestines. The virus is intermittently passed in stools and saliva for one month or more after infection. The spread is feco-oral with maximum excretion of the virus just prior to the onset of paralysis and during first two weeks after paralysis. The disease can pass from one patient to another, through contaminated fingers or indirectly through contaminated water, milk, food, flies, and articles of daily use. There are no long-term carriers

Incubation Period (the period between contact of disease and manifestation of symptoms) is usually between 7 and 14 days (Range 3 – 35 days)

Risk Increases With

Trauma, intramuscular injections and operative procedures undertaken during epidemics of polio or even administration of immunizing agents particularly alum-containing DPT can precipitate an attack of paralytic polio in children already infected. A mother passes immunity to foetus via the placenta, the concentration of antibodies being approximately equal to that of the mother (precisely the reason why a mother is told NOT to breast feed 1 hr before and 1 hr after a dose of oral polio vaccine).


  1. Vaccination
  2. Pulse Polio Immunization (PPI):

The purpose of doing PPI is to replace wild poliovirus with the vaccine virus in all the susceptible hosts. This is achieved by giving doses of OPV to all children in a defined age group, usually children 0 – 59 months of age, in as short a period of time as possible (preferably 1-2 days), regardless of their immunization status.