Polio: Symptoms & Signs

Medically Reviewed on 10/12/2021

Polio is an infectious disease. Polio is an abbreviation for the term poliomyelitis. The virus enters the mouth and multiplies in lymphoid tissues in the throat and intestine. The infection enters the blood and spreads to other sites, ultimately causing invasion of the central nervous system (CNS), the spinal cord, and brain.

Polio can be a minor illness, known as the abortive type of polio. This occurs in 80%-90% of clinical infections, chiefly in young children, and does not reach the CNS. In this case, symptoms and signs include slight fever, malaise, sore throat, headache, and vomiting 3-5 days after exposure. Recovery occurs in 24-72 hours.

When polio is a major illness, symptoms usually appear without prior illness, particularly in older children and adults, 7-14 days after exposure. Symptoms include

Recovery from this stage may be complete, or the patient may develop paralytic polio. In paralytic polio, about 50% of patients recover with no residual paralysis, about 25% are left with mild disabilities, and the remaining patients have severe permanent disability

Cause of polio

Infection with the poliovirus causes polio.

Other polio symptoms and signs

  • Areas of Hyperesthesia (Increased Sensation)
  • Fever
  • Malaise
  • Muscle Pain
  • Paresthesia (Altered Sensation)
  • Severe Headache
  • Sore Throat
  • Stiff Back
  • Stiff Neck
  • Vomiting


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Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.