Acute Flaccid Paralysis

Acute flaccid paralysis (AFP) is a rare clinical syndrome defined as the sudden onset of muscle weakness or paralysis, which may include respiratory and bulbar weakness. AFP has many causes, both infectious and non-infectious. Prior to widespread vaccination, the most common cause of acute flaccid paralysis was poliovirus infection. As a result of vaccination, wildtype polio cases have decreased dramatically, but polio cases do occur in some countries. Canada has been polio free since 1994.

Surveillance for AFP is a required to maintain Canada’s polio-free certification status. AFP surveillance is important for demonstrating (through the capacity to identify non-polio AFP cases) that detecting polio cases is possible, should they arise. AFP has been reportable in Ontario since 2013.

AFP surveillance is conducted as part of global polio eradication to rule out the possibility of poliovirus infection and document the absence of polio virus.

Canada monitors for cases of AFP in children less than 15 years old as a part the World Health Organization (WHO) surveillance efforts. From 1996 to 2017, there were between 27-63 cases of AFP reported annually in Canada, averaging 44 cases per year (PHAC, 2021).

AFP syndromic surveillance in Canada and Ontario on AFP is currently done by:

• Enhanced, active case-by-case notification by the Canadian Paediatric Surveillance Program (CPSP); and
• Enhanced, active case-by-case notification by paediatric tertiary care hospitals involved in the Immunization Monitoring Program, Active (IMPACT).

AFP is defined as acute onset of focal weakness or flaccid paralysis reduced tone or sudden onset of muscle weakness with no alternate cause (e.g., trauma).

Regardless of underlying etiology, weakness in AFP can affect any muscle group, including limbs, face, respiratory muscles, or bladder and bowel muscles. Transient weakness (weakness that lasts for a short period of time, such as post-ictal weakness), should not be considered when diagnosing AFP.

Guillain-Barré Syndrome (GBS), which generally begins with weakness in the hands and feet then quickly becomes widespread throughout the body, is an immune condition which is currently the most common cause of AFP in Canada. AFP due to GBS often presents as symmetrical paralysis and may progress for up to 10 days.

Patterns of paralysis and other symptoms such as pain or fever at onset depend on the underlying diagnosis. Potential for person-to-person transmission depends on the underlying cause.

Laboratory testing is needed to rule out or determine pathogens causing AFP. 

AFP can be caused by several infectious and non-infectious agents, some of which can lead to GBS. Causes include enteroviruses, echoviruses, adenoviruses, West Nile Virus, Campylobacter spp, Lyme disease, transverse myelitis, peripheral neuropathy, acute non-bacterial meningitis, brain abscess, China syndrome, tick paralysis, myasthenia gravis, porphyria, botulism, and heavy metal toxicity. 

Patients of any age with acute neurological presentations consistent with AFP should have laboratory testing done to detect a possible viral cause. This includes testing for enterovirus and poliovirus. 

Physicians can fill out Public Health Ontario Laboratories’ (PHOL) general test requisition with clinical and exposure-related information as appropriate. If polio is suspected in under/un-immunized persons with travel-related exposure risks, please contact PHOL for consultation and notify Ottawa Public Health immediately. 

When submitting specimens from patients with neurological presentation to PHOL, it is important to document the neurological symptoms on the laboratory requisition form, so the appropriate testing can be ordered. Specimen collection should include:

1. Stools: Collect two sets of stool samples at least 24 hours apart – divide each stool sample into a sterile container for viral testing and a bacterial (Cary-Blair) transport media container for Campylobacter testing. Write “Enterovirus / Enterovirus Molecular Serotyping” in the “Test(s) Requested” field of one requisition, and “Campylobacter Testing” in the “Test(s) Requested” of another requisition.
2. Respiratory specimens: Collect a nasopharyngeal (NP) swab and/or throat swab (NP swab preferred) in universal transport media (UTM), or bronchoalveolar lavage in a sterile dry container. Always submit a throat swab for children under 15 years of age with AFP. Write “Enterovirus / Enterovirus Molecular Serotyping" in the “Test(s) Requested” field of the requisition.
3. Cerebrospinal Fluid (CSF): For all ages, collect cerebrospinal fluid (CSF) as appropriate for the investigation. If CSF is collected, write “Enterovirus / Enterovirus Molecular Serotyping" in the “Test(s) Requested” field of the requisition.

For complete information and instructions on specimen collection, please see Public Health Ontario Lab’s (PHOL) Test Information Sheets on Enterovirus and Poliovirus.

Please report suspected or confirmed cases of AFP by the next business day. If polio is suspected in under/un-immunized persons with travel-related exposure risks, please contact PHOL for consultation and notify Ottawa Public Health immediately. 

Monday to Friday from 8:30 am to 4:30 pm: Call 613-580-2424, extension 24224 and leave a detailed, confidential message including your contact information or fax 613-580-9640.

After hours, on weekends, or holidays: Call 3-1-1 and ask to speak to Public Health on call. To have your call prioritized as a health care provider, please identify yourself and your reason for calling.

See also: Reporting a communicable disease

Management will depend on the causative agent.

Routine IPAC measures for hospitalized cases are recommended, and additional precautions depend on the causative organism.

In Ontario, AFP is a reportable condition. Please see Reporting a communicable disease for more information.

Information for Canadians regarding acute flaccid myelitis (AFM), Public Health Agency of Canada

Acute Flaccid Myelitis (AFM), U.S. Centers for Disease Control and Prevention (CDC)  

• Poliovirus Information, Public Health Ontario
• Poliomyelitis (Polio) and Acute Flaccid Paralysis, Public Health Ontario
• Enterovirus Information, Public Health Ontario
• Infectious Disease Protocol: Appendix 1: Case Definitions and Disease Specific Information Disease: Acute Flaccid Paralysis, Ministry of Health
• Infectious Disease Protocol Appendix 1: Case Definitions and Disease Specific Information Disease: Poliomyelitis, acute, Ministry of Health
• Surveillance of acute flaccid paralysis, Public Health Agency of Canada