You have been logged out of VisualDx or your session has expired.

Please reload this page and sign into VisualDx to continue.

  VisualDx Mobile   Select Language

Get VisualDx Mobile

There are VisualDx mobile apps available for iOS and Android devices.

You will need a VisualDx account to use the mobile apps.

Already have an account? Sign In or
sign up for a free trial.

Users with VisualDx accounts earn CME credits for using VisualDx.

Already have an account? Sign In or
sign up for a free trial.

Create a Personal Account

E-mail (username)
Verify Password
First Name
Last Name

Personal Account Created

Mobile Access

You can now download VisualDx for your iOS and Android devices. Launch the VisualDx app from your device and sign in using your VisualDx personal account username and password.

CME Certification

Sign in with your personal account to earn and claim CME credits through VisualDx. Credits can be earned by building a differential or looking up a diagnosis.

Version: 7.13.1441   (build df7aed4)
Select Language

Select Region

Send us your feedback

This field is required

Oops! There was an issue during submission. Please try again. If the problem persists, email with your feedback.

Thank You!

We appreciate your feedback and you will be hearing from us soon.


Share This Page

Thank You!

We have sent an e-mail with a link to the current page.


E-mail This Patient Information Sheet

Thank You!

We have sent an e-mail with this patient information.


Image Contributors


  • Christine Ahn MD
    Carl Allen DDS, MSD
    Brandon Ayres MD
    Howard P. Baden MD
    Robert Baran MD
    Keira Barr MD
    Gregory J. Basura MD, Ph.D
    Donald Belsito MD
    Jeffrey D. Bernhard MD
    Jesse Berry MD
    Victor Blanco MD
    Benjamin R. Bohaty MD
    William Bonnez MD
    Sarah Brenner MD
    Robert A. Briggaman MD
    Robert Brodell MD
    Roman Bronfenbrener MD
    Walter Brooks MD
    William Buckley MD
    Philip Bulterys MD, PhD (candidate)
    Susan Burgin MD
    Sonya Burton MD
    Sean P. Bush MD, FACEP
    Jeffrey Callen MD
    Scott Camazine MD
    Michael Cardwell
    Shelley D. Cathcart MD
    Robert Chalmers MD, MRCP, FRCP
    Chia-Yu Chu MD, PhD
    Flavio Ciferri MD
    Maria Rosa Cordisco MD
    Noah Craft MD, PhD
    John T. Crissey MD
    Harold E. Cross MD, PhD
    Charles E. Crutchfield III MD
    Adriana Cruz MD
    Donna Culton MD, PhD
    Bart J. Currie MBBS, FRACP, DTM&H
    Chicky Dadlani MD
    Alexander Dane DO
    C. Ralph Daniel III MD
    Thomas Darling MD, PhD
    William Delaney MD
    Damian P. DiCostanzo MD
    Ncoza Dlova MD
    James Earls MD
    Libby Edwards MD
    Melissa K. Egge MD
    Charles N. Ellis MD
    Rachel Ellis MD
    David Elpern MD
    Nancy Esterly MD
    Stephen Estes MD
    E. Dale Everett MD
    Janet Fairley MD
    David Feingold MD
    Jennifer J. Findeis-Hosey MD
    Benjamin Fisher MD
    Henry Foong MBBS, FRCP
    David Foster MD, MPH
    Brian D. Foy PhD
    Michael Franzblau MD
    Vincent Fulginiti MD
    Sunir J. Garg MD, FACS
    Kevin J. Geary MD
    Lowell Goldsmith MD, MPH
    Sethuraman Gomathy MD
    Bernardo Gontijo MD, PhD
    Kenneth Greer MD
    Kenneth G. Gross MD
    Alan Gruber MD
    Nathan D. Gundacker MD
    Akshya Gupta MD
    Vidal Haddad MSC, PhD, MD
    Edward Halperin MD, MA
    Ronald Hansen MD
    John Harvey
    Rizwan Hassan MD
    Michael Hawke MD
    Jason E. Hawkes MD
    Peter W. Heald MD
    David G. Hicks MD
    Sarah Hocker DO
    Ryan J. Hoefen MD, PhD
    Li-Yang Hsu MD
    William Huang MD
    Sanjana Iyengar MD
    Alvin H. Jacobs MD
    Saagar Jadeja MD
    Shahbaz A. Janjua MD
    Joshua J. Jarvis MD
    Kit Johnson
    Zachary John Jones MD
    Robert Kalb MD
    A. Paul Kelly MD
    Henry Kempe MD
    Loren Ketai MD
    Sidney Klaus MD
    Ashwin Kosambia MD
    Jessica A. Kozel MD
    Carl Krucke
    Mario E. Lacouture MD
    Joseph Lam MD
    Alfred T. Lane MD
    Edith Lederman MD
    Nahyoung Grace Lee MD
    Pedro Legua MD, PhD
    Robert Levin MD
    Bethany Lewis MD
    Sue Lewis-Jones FRCP, FRCPCH
    Taisheng Li MD
    Christine Liang MD
    Shari Lipner MD, PhD
    Adam Lipworth MD
    Jason Maguire MD
    Mark Malek MD, MPH
    Jere Mammino DO
    Ricardo Mandojana MD
    Lynne Margesson MD
    Thomas J. Marrie MD
    Maydel Martinez MD
    Ralph Massey MD
    Patrick McCleskey MD
    Karen McKoy MD
    Thomas McMeekin MD
    Josette McMichael MD
    Somchai Meesiri MD
    Joseph F. Merola MD
    Mary Gail Mercurio MD
    Anis Miladi MD
    Larry E. Millikan MD
    Dan Milner Jr. MD
    Zaw Min MD
    Stephanie Montero
    Alastair Moore MD
    Keith Morley MD
    Dean Morrell MD
    Samuel Moschella MD
    Rehan Naseemuddin MD
    Taimor Nawaz MD
    Vic Newcomer MD
    John Nguyen MD
    Matilda Nicholas MD
    Thomas P. Nigra MD
    Steven Oberlender MD, PhD
    Maria Teresa Ochoa MD
    Art Papier MD
    Lawrence Parish MD
    Tanner Parrent MD
    Mukesh Patel MD
    Lauren Patty-Daskivich MD
    David Peng MD, MPH
    Robert Penne MD
    Nitipong Permpalung MD
    Miriam Pomeranz MD
    Doug Powell MD
    Harold S. Rabinovitz MD
    Christopher J. Rapuano MD
    Sireesha Reddy MD
    Angela Restrepo MD, PhD
    Bertrand Richert MD, PhD
    J. Martin Rodriguez, MD, FACP
    Theodore Rosen MD
    Misha Rosenbach MD
    Scott Schiffman MD
    Robert H. Schosser MD
    Glynis A. Scott MD
    Carlos Seas MD, MSc
    Deniz Seçkin MD
    Daniel Sexton MD
    Paul K. Shitabata MD
    Tor Shwayder MD, FAAP, FAAD
    Elaine Siegfried MD
    Gene Sienkiewicz MD
    Christye Sisson
    Philip I. Song MD
    Mary J. Spencer MD, FAAP
    Lawrence B. Stack MD
    Sarah Stein MD
    William Van Stoecker MD
    Frances J. Storrs MD
    Erik J. Stratman MD
    Lindsay C. Strowd MD
    Erika Summers MD
    Belinda Tan MD, PhD
    Robert Tomsick MD
    Hensin Tsao MD, PhD
    Richard P. Usatine MD
    Jenny Valverde MD
    Vishalakshi Viswanath MD
    Susan Voci MD
    Lisa Wallin ANP, FCCWS
    Douglas Walsh MD
    Ryan R. Walsh MD
    George Watt MD
    Clayton E. Wheeler MD
    Sally-Ann Whelan MS, NP, CWOCN
    Jan Willems MD, PhD
    James Henry Willig MD, MPH
    Karen Wiss MD
    Vivian Wong MD, PhD
    Sook-Bin Woo MS, DMD, MMSc
    Jamie Woodcock MD
    Stephen J. Xenias MD
    Nathaniel Yohannes
    Lisa Zaba MD
    Vijay Zawar MD
    Bonnnie Zhang MD
    Carolyn Ziemer MD
    Jeffrey P. Zwerner MD, PhD


  • Am. Journal of Trop. Med & Hygiene
  • Armed Forces Pest Management Board
  • Blackwell Publishing
  • Bugwood Network
  • Centers For Disease Control and Prevention
  • Centro Internacional de Entrenamiento e Investigaciones Mèdicas (CIDEIM)
  • Dermatology Online Journal
  • East Carolina University (ECU), Division of Dermatology
  • International Atomic Energy Agency
  • Massachusetts Medical Society
  • Oxford University Press
  • Radiological Society of North America
  • Washington Hospital Center
  • Wikipedia
  • World Health Organization
ContentsSynopsisCodesLook ForDiagnostic PearlsDifferential Diagnosis & PitfallsBest TestsManagement PearlsTherapyReferencesView all Images (10)
Other Resources UpToDate PubMed


Print Images (10)
Contributors: Mobeen Yousaf MD, Ankit Rohatgi MD, Naila Choudhary MD, Nayef El-Daher MD, PhD, Zaw Min MD, FACP
Other Resources UpToDate PubMed


Poliomyelitis, also known as polio or infantile paralysis, is a disease of the central nervous system (CNS) that preferentially infects and destroys the motor neurons, leading to muscle weakness and acute flaccid paralysis. Poliomyelitis is caused by infection with poliovirus (PV), a member of the genus Enterovirus. Outbreaks in Europe and the United States were first reported in the early and mid-19th century, respectively, and polio became one of the most feared childhood diseases of the 20th century, with infection peaking in the United States in the 1950s. Since then, worldwide prevalence has decreased significantly because of the development of the polio vaccine and as a result of aggressive immunization programs under the surveillance of the World Health Organization (WHO).

Polio no longer poses a public health threat in the United States. No cases of wild-type PV infection have been reported since 1979. From 1980 to 1999, an average of 8 cases per year were reported in the United States, 95% of which were due to vaccine-associated paralytic polio (VAPP) caused by live oral polio vaccine (OPV) (with the remaining cases imported or indeterminant). Starting in 2000, the Advisory Committee on Immunization Practices recommended the exclusive use of inactivated PV vaccine (IPV) in routine immunizations in the United States to eliminate VAPP.

Areas of endemic wild-type PV still exist in other areas of the world such as Pakistan, Nigeria, and Afghanistan. Moreover, several countries are considered to have active transmission of imported PV, including Equatorial Guinea, Iraq, Cameroon, Syria, Ethiopia, and Somalia.

Mortality observed in paralytic polio is due to respiratory failure, although this has not occurred in the United States since 1979. Incidence is equal in males and females. Poliomyelitis tends to be a disease mainly of children; however, it can affect individuals of any age, especially those who are immunocompromised.

PV is transmitted feco-orally by the ingestion of contaminated water or, during epidemics, via pharyngeal spread. PV infects and causes disease only in humans. It is highly contagious. In temperate climates, infection is seasonal, with peak transmission occurring in summer and autumn. Three serotypes of PV have been identified: PV types 1 (PV1), 2 (PV2), and 3 (PV3). All are extremely virulent and produce the same symptoms. PV1 is the most common and is most frequently associated with paralysis.

After entering the mouth, the organism tends to infect the cells of the mouth, nose, and throat. It binds to an immunoglobulin-like receptor, known as the PV receptor or CD155, on the cell membrane. 90%-95% of PV infections are asymptomatic. There is an incubation period of 3-35 days (minimum range 6-20 days), during which the virus undergoes primary replication in the lymphatic tissues of the gastrointestinal tract using the host cells' own machinery. An asymptomatic primary (minor) transient viremia occurs, with spread of virus to the systemic reticuloendothelial tissue throughout the body. In 4%-8% of individuals, a second (major) viremia occurs, which manifests as influenza-like symptoms; this may rarely progress to invasion of the CNS, resulting in a local inflammatory response in the form of nonparalytic aseptic meningitis. In about 1% of these patients, the PV then causes selective destruction of motor neurons in the spinal cord, brain stem, or motor cortex leading to the development of various forms of paralytic poliomyelitis (spinal, bulbar, or bulbospinal, respectively). The mechanism of spread of PV to the CNS is unclear. It may occur by direct passage of the virus from blood by crossing the blood-brain barrier, or it may occur by retrograde axonal transport from muscle to spinal cord and brain. After invading the CNS, the virus uncoats, viral replication occurs, and the motor neuron dies, leading to paralysis of muscle fibers supplied by this motor neuron. Spread of the virus to neighboring motor neurons may occur laterally, independent of axonal transport, or by transneuronal spread in a retrograde transport-dependent fashion. Other neurons can be infected as well, producing brainstem encephalitis and respiratory insufficiency.

The virus can cross the placenta during pregnancy but does not seem to affect the fetus, either by maternal infection or vaccination. Maternal antibodies also cross the placenta, providing passive immunity during the first few months of life.

Risk factors for infection as well as severe disease include:
  • Malnutrition
  • Immune deficiency
  • Pregnancy
  • Tonsillectomy
  • Physical activity immediately after the onset of paralysis
Clinical course:
Primary viremia (abortive polio) is asymptomatic. In 4%-8% of patients, this is followed by a second major viremia manifesting as a flu-like illness with headache, sore throat, fever, nausea, vomiting, malaise, and fatigue. A fraction of patients in this group can have invasion of the CNS and inflammation of the meninges, causing neck stiffness, headache, fever, and vomiting and, in some patients, selective destruction of motor neurons; depending on the anatomical site, this causes severe back pain, neck/muscle pain, and the development of motor weakness. Such paralysis occurs in only about 0.1% of all PV infections. Weakness may vary, from 1 muscle or group of muscles to quadriplegia and respiratory failure.
  • Spinal polio – Tone is reduced, nearly always in an asymmetric manner, with lower motor neuron destruction. Proximal muscles usually are affected more than distal muscles, and legs more commonly than arms. Reflexes are decreased or absent. The sensory examination is normal. Weakness typically worsens over 2-3 days, although sometimes worsening can progress for up to a week. Muscle atrophy is generally observed several weeks after onset of symptoms. Recovery may be complete, partial, or absent.
  • Bulbar polio – Bulbar involvement occurs in 5%-35% of patients, producing dysphagia, dysarthria, and difficulty handling secretions. Approximately 19% of all paralytic polio cases have both bulbar and spinal symptoms.
  • Respiratory polio (bulbospinal polio) – Bulbospinal polio affects the upper part of the cervical spinal cord (C3 through C5), and causes paralysis of the diaphragm along with difficulty in swallowing. There may be encephalitis, usually in infancy.
  • Post-polio syndrome – Recurrences of weakness or fatigue may occur in some patients decades (20-40 years) after initial infection and disease. The same groups of muscles are usually involved, but weakness can extend to muscles that were not involved during the initial infection. The prognosis is generally good, though the actual cause of the syndrome is poorly understood. It is, at least, not secondary to persistent or reactivated PV infection. Patients may also experience chronic pain, contractures, depression, fatigue, and sleep problems.
It is worth noting that there are 2 types of paralytic diseases associated with OPV:
  1. VAPP – Usually occurs after the first dose of OPV, and its estimated incidence is 1 person per 2.5 million doses. It is thought to be due to mutation of the vaccine virus to a neurovirulent type. The disease may occur in the vaccinated individual or a close contact of that person. Predisposing factors include B-cell immunodeficiencies and hypogammaglobulinemia.
  2. Vaccine-derived poliomyelitis – Refers to outbreaks of poliomyelitis in regions with low immunization rates when OPV vaccination starts. The mechanism appears to be mutation of vaccine virus to naturally occurring wild-type PV.


A80.9 – Acute poliomyelitis, unspecified

398102009 – Acute poliomyelitis

Look For

Subscription Required

Diagnostic Pearls

Subscription Required

Differential Diagnosis & Pitfalls

Clinically, the illnesses that most resemble poliomyelitis are other enterovirus infections, West Nile virus, and Guillain-Barré syndrome. It is particularly important to identify Guillain-Barré syndrome and to distinguish it from a viral disorder of the motor neurons; treatment for Guillain-Barré syndrome with intravenous immune globulin or plasma exchange should be instituted early, whereas the other diagnoses have only symptomatic treatment.

Best Tests

Subscription Required

Management Pearls

Subscription Required


Subscription Required


Subscription Required

Last Updated: 09/04/2015
Copyright © 2018 VisualDx®. All rights reserved.
Print 10 Images
View all Images (10)
(with subscription)
Poliomyelitis (Abortive) : Abdominal pain, Fever, Headache, Nausea, Vomiting, Constipation, Anorexia, Nuchal rigidity, Pharyngitis
Clinical image of Poliomyelitis
Copyright © 2018 VisualDx®. All rights reserved.