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Acute Flaccid Paralysis (AFP)

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Reporting Obligations

Confirmed and suspected cases shall be reported to local Health Unit.

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Aetiologic Agent

AFP is a clinical syndrome, typically characterized by rapid onset weakness, which may include respiratory and bulbar weakness. AFP is a broad clinical syndrome with an array of diagnostic possibilities, and may be the result of infectious or non-infectious agents. Surveillance is conducted in an attempt to identify cases of AFP and to investigate all reported cases for evidence to rule out poliomyelitis (polio), which is essential for maintaining Canada’s polio-free status.

AFP may be caused by a number of agents. The immune-mediated condition Guillain-Barré Syndrome (GBS) is the most common cause of AFP in Canada. The causes of AFP, some of which lead to GBS, include, but are not limited to, enteroviruses (including poliovirus), echoviruses, adenoviruses, acute West Nile virus infection, Campylobacter spp., transversemyelitis, peripheral neuropathy, acute non-bacterial meningitis, brain abscess, China syndrome, post-polio sequelae, tick paralysis, myasthenia gravis, porphyria and botulism.

Clinical Presentation

Acute onset of focal weakness or paralysis, characterized as flaccid without other obvious causes (e.g., trauma), in children less than 15 years old.

The most characteristic feature of AFP associated with paralytic polio is its asymmetric distribution (not affecting both sides equally), which affects some muscle groups while sparing others, with fever present at onset. The most typical pattern is involvement of one leg only, or one arm, although this occurs less often. It is less common for both legs or both arms to be affected.

AFP due to GBS may present as symmetrical paralysis and may progress for up to 10 days.

Modes of Transmission

Depends on causative agent.

Incubation Period

Depends on causative agent.

Period of Communicability

Varies, depending on causative agent.

Risk Factors/Susceptibility

Depends on causative agent.

Diagnosis and Laboratory Testing

Clinically confirmed case: Acute onset of focal weakness or paralysis characterized as flaccid (reduced tone) without other obvious cause (e.g. trauma) in children <15 years old. Cases of Guillain-Barré Syndrome (GBS) should be included as cases of Acute Flaccid Paralysis (AFP). Transient weakness (e.g. post-ictal weakness) should not be reported. AFP is a syndrome which can be caused by a number of pathogens. The following laboratory testing (of stool, respiratory secretions, cerebrospinal fluid (CSF) and other appropriate clinical specimens) is used to rule out poliomyelitis and/or determine pathogens causing AFP:

  • Stool samples – collection of two stool samples within two weeks (up to six weeks) after the onset of paralysis for viral studies and campylobacter
  • Viral throat swab
  • Serology testing is not recommended for diagnosis of polio or non-polio enterovirus infection
  • Depending on the clinical presentation, a nasopharyngeal swab, and/or cerebrospinal fluid (CSF) may be collected to assist with the investigation
  • Neurologic investigations, as appropriate, should take place (electromyography, nerve conduction studies, MRI, CT)

See guidelines for reporting, testing and forms to complete from Public Health Ontario – Public Health Ontario – Additional Testing Guideline for AFP/AFM at PHO’s Laboratory.

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Treatment and Case Management

Treatment is under the direction of the attending health care provider.

Routine Practices are recommended for hospitalized cases and additional precautions would depend on the causative organism.

An investigation to rule out paralytic polio should be undertaken.

Additional Resources

Public Health Ontario – Additional Testing Guideline for AFP/AFM at PHO’s Laboratory


Ministry of Health and Long-Term Care, Infectious Diseases Protocol, 2022.