Last updated: February 10, 2023

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Poliomyelitis, or polio, is a disease caused by poliovirus, a type of human Enterovirus. Poliovirus spreads via fecal-oral transmission. Although the majority of poliovirus infections are asymptomatic, some may invade the central nervous system, leading to motor neuron death and irreversible paralysis that can cause respiratory insufficiency and death. Symptomatic poliomyelitis most commonly manifests as a flu-like illness. In rare cases, patients develop paralytic poliomyelitis, which manifests with weakness, decreased muscle tone, and hyporeflexia. The diagnosis is established based on polymerase chain reaction (PCR) findings of poliovirus RNA in body fluid samples (e.g., stool, oropharyngeal swab, cerebrospinal fluid). Poliomyelitis has been eradicated in most parts of the world as a result of global vaccination initiatives. The treatment of poliomyelitis is mainly supportive. Patients with brainstem or respiratory muscle involvement may require intubation and mechanical ventilation. The majority of patients with paralytic poliomyelitis do not regain their full strength after recovery. Some patients go on to develop post-polio syndrome, which is characterized by progressive disability and muscle weakness decades after the initial infection.

  • As a result of widespread vaccination measures, poliomyelitis has largely been eradicated in most countries worldwide.
  • In 2022, paralytic poliomyelitis due to vaccine-derived poliovirus was confirmed in an unvaccinated individual in New York. [1]
  • Poliovirus is still endemic in Afghanistan and Pakistan. [2]

Epidemiological data refers to the US, unless otherwise specified.

  • Causative agent
  • Route of transmission [2]
    • Fecal-oral: absorption of poliovirus in the intestinal tract
    • Droplet (rare)
  • Incubation time: 7–14 days [3]

Over 72% of infections with poliovirus are asymptomatic. Clinical infection (mostly flu-like symptoms) is observed in less than 24% of cases and less than 1% of infected individuals develop paralysis. The clinical forms of poliomyelitis are: [3][4]

Poliomyelitis without CNS involvement (abortive poliomyelitis)

Poliomyelitis with CNS involvement

Nonparalytic poliomyelitis: aseptic meningitic form

  • Begins several days following abortive poliomyelitis (often temporary, symptom-free interval)
  • Fever, neck stiffness, headache, vomiting, muscle pain
  • Neck muscle weakness (head drop sign: head falls back when placed in a supine position)
  • No paresis

Paralytic poliomyelitis

  • Post-polio syndrome (PPS) [5]
    • Most frequent complication observed following poliovirus infection (up to 40% of survivors)
    • Occurs decades after infection
    • Manifests with progressive muscle weakness and pain, even in areas that were not affected by the initial infection
  • Consider poliomyelitis in unvaccinated patients with nonspecific viral symptoms who: [6]
    • Live in areas with known community spread
    • Have recently traveled to a region where polio has not been eradicated or OPV is still utilized
  • Initial test: PCR of stool or oropharyngeal samples to test for enterovirus [7]
  • Confirmatory test: PCR of CSF, stool, or oropharyngeal samples to test for poliovirus RNA [6]
  • CSF will show:

The differential diagnoses listed here are not exhaustive.

  • The prognosis is dependent on the form of poliomyelitis.
  • In the abortive and nonparalytic forms, complete recovery without complications occurs within 2 weeks.
  • In the paralytic form, the most serious short-term risk is death due to diaphragmatic involvement. After recovery, most patients have residual deficits, including muscle weakness or contractures and muscle pain.
  • Post-polio syndrome may lead to muscle weakness and pain decades after polio infection.
  • Immunization [8]
    • The inactivated poliovirus vaccine (IPV) is recommended for childhood immunization in the US.
    • In the US, children receive 4 doses of IPV, at 2, 4, and 6–18 months; , followed by a booster dose at 4–6 years; . See “Immunization schedule.”
    • Consider a one-time booster dose of IPV in previously vaccinated adults at increased risk of exposure to poliovirus. [6]
    • The live attenuated oral poliovirus vaccine (OPV) is used for childhood immunization in resource-limited countries because it is less costly. It has a slightly increased risk of vaccine-associated paralytic polio and is being gradually replaced worldwide in favor of the IPV.
  1. Link-Gelles R, Lutterloh E, Schnabel Ruppert P, et al. Public Health Response to a Case of Paralytic Poliomyelitis in an Unvaccinated Person and Detection of Poliovirus in Wastewater — New York, June–August 2022. MMWR Morb Mortal Wkly Rep. 2022; 71 (33): p.1065-1068. doi: 10.15585/mmwr.mm7133e2 . | Open in Read by QxMD
  2. Poliomyelitis (Polio). https://www.who.int/health-topics/poliomyelitis#tab=tab_2. . Accessed: February 10, 2023.
  3. Global Health: Polio. https://www.cdc.gov/polio/about/index.htm. Updated: October 15, 2014. Accessed: March 2, 2017.
  4. Epidemiology and Prevention of Vaccine-Preventable Diseases.
  5. Post-Polio Syndrome. https://www.cdc.gov/polio/us/pps.html. Updated: August 2, 2016. Accessed: June 13, 2017.
  6. Poliomyelitis: For Healthcare Providers. https://www.cdc.gov/polio/what-is-polio/hcp.html. Updated: August 10, 2022. Accessed: September 23, 2022.
  7. Larkin H. What All Physicians Need to Know About the Polio Resurgence in New York State. JAMA. 2022; 328 (11): p.1020. doi: 10.1001/jama.2022.15171 . | Open in Read by QxMD
  8. Child and Adolescent Immunization Schedule. Recommendations for Ages 18 Years or Younger, United States, 2022. https://web.archive.org/web/20220809054312/https://www.cdc.gov/vaccines/schedules/hcp/imz/child-adolescent.html. Updated: February 17, 2022. Accessed: August 9, 2022.

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