Note: Individuals infected with the poliovirus are often asymptomatic. In approximately 25% of cases, polio presents as a mild to moderate illness marked by headache, fever, sore throat, vomiting, diarrhea, and fatigue. Polio affects the central nervous system only infrequently with inflammation and sometimes destruction of the motor neurons in the gray matter of the spinal cord and brain stem. Central nervous system involvement results in temporary or permanent muscle weakness or motor paralysis especially of the limbs and typically the legs. Polio may become life-threatening when paralysis affects the muscles involved in breathing and swallowing.
Mary Beth Norton et al.Betsy McKaycalled also infantile paralysis, poliomyelitis
see post-polio syndromeExamples of polio in a Sentence
Fatma Tanis, NPR, 16 July 2025
In high-income countries, vaccine hesitancy and distrust in institutions have led to a resurgence of vaccine-preventable diseases, including measles and polio.
—Jade Walker, CNN Money, 15 July 2025
In the days before vaccines, smallpox and polio and measles killed.
—New York Daily News Editorial Board, New York Daily News, 9 July 2025
The global network of 700 measles and rubella labs is at risk of collapse, malaria diagnoses and deliveries of bed nets and medicines have been delayed, the polio and mpox programs are unable to function as before.
—Isabelle Mayault, The Dial, 8 July 2025
See All Example Sentences for polio
Cite this Entry
“Polio.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/polio. Accessed 4 Aug. 2025.
Copy CitationKids Definition
polio
noun
Medical Definition
polio
noun
Note: Individuals infected with the poliovirus are often asymptomatic. In approximately 25% of cases, polio presents as a mild to moderate illness marked by headache, fever, sore throat, vomiting, diarrhea, and fatigue. Polio affects the central nervous system only infrequently with inflammation and sometimes destruction of the motor neurons in the gray matter of the spinal cord and brain stem. Central nervous system involvement results in temporary or permanent muscle weakness or flaccid paralysis of muscles especially of the limbs and typically the legs. Polio may become life-threatening when paralysis affects the muscles involved in breathing and swallowing.
People WeeklyEvan Johnson, The Addison County (Vermont) Independentcalled also infantile paralysis, poliomyelitis
see post-polio syndrome
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