Guidance

How to report a case of acute flaccid paralysis or acute flaccid myelitis

Updated 21 August 2025

Applies to England

Introduction

Under Schedule 1 of the Health Protection (Notification) Regulations 2010, suspected cases of acute poliomyelitis are notifiable. Additionally, as of 6 April 2025, acute flaccid paralysis (AFP) or acute flaccid myelitis (AFM) not explained by a non-infectious cause are also notifiable.

Although the UK has been certified as polio free by the World Health Organization (WHO) since 2003, in order to maintain this status, there is a need to demonstrate that cases with a possible diagnosis of poliomyelitis are adequately investigated to exclude infection with wild poliovirus or vaccine-derived poliovirus. To facilitate this, any clinical case of AFP/AFM where an infectious causative agent is suspected should be reported to UKHSA and investigated appropriately.

In addition, other non-polio enteroviruses such as EV-D68 can also cause severe presentations including AFP and AFM, as demonstrated in An increase in reports of AFP in the UK, 1 January 2018 to 21 January 2019: early findings. Reporting all cases of AFP and AFM not explained by a non-infectious cause will strengthen our understanding of these other pathogens by ensuring appropriate samples are collected and forwarded on to the Enteric Virus Unit for further characterisation.

This page describes how reports of clinical cases of AFP and AFM not explained by a non-infectious cause should be made to the UK Health Security Agency (UKHSA) and the follow-up and virological investigations that need to be undertaken.

Case definition

AFP or AFM is characterised by rapid onset of weakness of an individual’s extremities, often including weakness of the muscles of respiration and swallowing, progressing to maximum severity within 10 days. The term ‘flaccid’ indicates weakness accompanied by hyporeflexia or areflexia in the affected limb or limbs.

Aims of surveillance

Aims of surveillance are to:

• investigate and exclude poliovirus infection
• investigate the potential contribution of other enteroviruses, especially enterovirus D68
• systematically characterise the illness and document long-term sequelae
• increase awareness of guidance on investigation and management of cases
• act as a focal point for national and international collaboration

How to report

1. Health professionals managing patients meeting the above case definition should report them to the local Health Protection Team. UKHSA will then provide a case ID.

2. An online enhanced surveillance survey should then be completed by the responsible clinician.

The survey captures relevant clinical and epidemiological data:

• patient details
• presenting symptoms, particularly neurological and respiratory symptoms
• investigations performed to date, including virology, and results
• details and results of any neuroradiological investigations
• polio vaccination history, if available
• recent overseas travel history, if available

If you have any queries or suggestions, contact phe.afp@nhs.net

Samples to be sent to reference laboratory

The following samples should be taken as close as possible to the onset of neurological signs and symptoms and sent to the UKHSA Virus Reference Department (VRD), accompanies by an E72 report form.

Essential:

• 2 stool specimens (24 to 48 hours apart, within 2 weeks of onset of illness)
• throat swabs or nasopharyngeal aspirate (NPA) and
• cerebrospinal fluid (CSF), if collected

Further information

Appendix 1 contains further sample collection and processing details, including contact details for the VRD.

Information for patients or parents of children with AFP or AFM is available.

Appendix 1: Samples for AFP or AFM investigation

Samples required by UKHSA for the investigation of AFP and AFM cases

Complete sample sets should be sought for all AFP or AFM cases to maximise the likelihood of identifying enteroviruses.

The following samples should be collected, as close as possible to the onset of neurological signs and symptoms, and forwarded to the Virus Reference Department, UKHSA Colindale. Locally stored samples may be forwarded if they are available and are of appropriate quality (see note 1).

Essential:

• 2 stool specimens (24 to 48 hours apart, within 2 weeks of onset of illness) (see note 2)
• throat swabs or nasopharyngeal aspirate (NPA) (see note 3)
• cerebrospinal fluid (CSF), if collected (see note 4)

Notes

1.  Stored and fresh samples (of any sample type) should be original clinical materials. For non-faecal samples, cDNA or RNA extracts will only be accepted if original clinical materials are no longer available or are of insufficient volume; please contact the Enteric Virus Unit (EVU) prior to sending cDNA/extracts. Material in which enterovirus has been detected should always be included in the sample set; if there are multiple positive samples, please ensure those with the lowest Ct values are included. If enterovirus has not been detected locally, the requested sample set should still be forwarded.

2.  Stool specimens are required to exclude polio by poliovirus isolation, for all cases of AFP or AFM. Unadulterated stools, minimum 2g each and 2 separate samples collected 24 to 48 hours apart, should be forwarded. Referral of materials does not need to be delayed until both samples are available; each specimen may be submitted independently. These should be collected within 2 weeks of onset of illness and appropriate, stored samples may be forwarded. If more than 2 weeks have passed since onset of illness and no earlier material is available, obtain 2 fresh stool samples. Faecal suspensions and faecal emulsions are unsuitable for poliovirus isolation. If it is impossible to collect stool samples, rectal swabs will be accepted. All faecal samples will also be tested for non-polio enteroviruses using molecular methods.

3.  Upper respiratory tract (URT) samples are important for the identification of enteroviruses that may be present in the URT whilst being undetectable in faecal samples, for example, EV-D68 and EV-A71. Example sample types include viral nose and throat swabs in UTM/VTM and nasopharyngeal aspirates.

4.  If CSF has been obtained, it should be forwarded regardless of local testing results. Note some enteroviruses, including EV-D68, are rarely detected in CSF, and testing of other sample types is required.

Request forms

Use the E72 report form: Polio, AFP and AFM surveillance: laboratory sample submission.

Complete the form in full, ensuring that all clinical and epidemiological details are included – this information is essential for assigning the sample to the correct laboratory.

Provide a contact telephone number to allow follow-up by a consultant microbiologist or virologist.

Contacts

Virus reference department (VRD)
UK Health Security Agency
61 Colindale Avenue
London
NW9 5HT
Email: vrdqueries@ukhsa.gov.uk
Telephone: 0208 327 7887
DX address: UKHSA Colindale VRD, DX 6530006

Laboratory and technical advice

Cristina Celma
Enteric Virus Unit: 020 8327 7846 Cristina.Celma@ukhsa.gov.uk

Stuart Beard
Enteric Virus Unit: 020 8327 6225
stuart.beard@ukhsa.gov.uk

Polio reference service
Polio Reference Service: 0208 327 7887
vrdqueries@ukhsa.gov.uk
UKHSA Colindale VRD: DX 6530006

Clinical advice including laboratory investigations

Please contact Dr Anika Singanayagam at the Virus Reference Department in the first instance:
+44 20 7123 2673
anika.singanayagam@ukhsa.gov.uk

If they are unavailable, please ask to speak to the Duty Virologist:
Virus Reference Department: 020 8327 6226
Monday to Friday 9am to 5pm