Acute flaccid paralysis syndrome
Information on the reporting, investigation and management of acute flaccid paralysis (AFP) and acute flaccid myelitis (AFM).
Acute flaccid paralysis (AFP) is a rare but serious neurological illness which is normally due to inflammation of the spinal cord, known as acute flaccid myelitis (AFM).
Acute flaccid paralysis or myelitis 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.
In the past, AFP was commonly due to poliovirus infection.
The success of the vaccination programme means that polio is now very rare internationally and has been eliminated in the UK; however, AFP may be linked to other viral infections including non-polio enteroviruses.
Regulation 2(1)(b) of the Health Protection (Notification) Regulations 2010 place a duty on registered medical practitioners (RMPs) to report any suspected infections that present or could present significant harm to human health. This covers reporting of acute flaccid paralysis (AFP) and acute flaccid myelitis (AFM) not explained by a non-infectious cause. Appropriate testing of AFP or AFM cases not explained by a non-infectious cause, to exclude polio as a causative agent, is an integral component of polio surveillance. In addition, under Schedule 1 of the Health Protection (Notification) Regulations 2010, suspected cases of acute poliomyelitis are notifiable.
To report a case, please contact the local health protection team (HPT).
Current situation and interpretation
The World Health Organization (WHO) Global Specialised Polio Laboratory located at the National Institute for Biological Standards and Control (NIBSC) conducts routine environmental surveillance for wild type and vaccine-like polio viruses as part of the UK’s commitment to the WHO global polio eradication programme.
Vaccine-like type 2 poliovirus (PV2) isolates have been found in multiple sewage samples collected from the London Beckton Sewage Treatment Works between February and June 2022. This sewage treatment plant covers a large catchment area across North and East London and a population close to 4 million.
During this period, there has been some virus evolution. The virus isolated in the most recent samples contained 6 and 7 VP1 nucleotide changes from the Sabin 2 vaccine strain respectively and therefore is now classified as a vaccine-derived poliovirus (VDPV2).
An average of 1 to 3 poliovirus isolates per year have been detected from UK sewage samples in recent years. However, these have all been single detections which are unrelated to each other. In this instance, the isolates identified between February and June 2022 are genetically related. This has prompted the need to investigate the extent of transmission of this virus in Northeast London.
The most likely scenario is that a recently vaccinated individual entered the UK before February 2022 from a country where oral polio vaccine (OPV) has been used for supplementary immunisation campaigns. While the UK stopped using OPV in 2004, several countries, including Pakistan, Afghanistan and Nigeria have continued to use OPV containing type 2 virus for outbreak control.
A national enhanced incident response has been declared by UKHSA and an Incident Management Team established. The WHO has now formally confirmed that the UK has a ‘circulating’ VDPV2 based on the detection of the same isolate for more than 60 days, and evidence that the virus detected in London is genetically linked to the poliovirus detected in Israel and the US.
Data
Current enterovirus strains detected in Virus Reference Department in Colindale.
An increase in reports of acute flaccid paralysis (AFP) in the United Kingdom in 2018 and 2019
During 2018, the United Kingdom has experienced an increase in reports of cases of AFP. As at 24 September 2019, 57 cases had been identified since 1 Jan 2018 with a peak in October 2018. The increase was temporally associated with an upsurge in enterovirus (EV) D68 activity. A national task force has been established and investigations are ongoing (Eurosurveillance Vol 24 Issue 6, published 7 February 2019).
Guidance for healthcare professionals
Information for parents and patients
Last updated 16 November 2022 + show all updates
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Updated information on acute flaccid paralysis and acute flaccid myelitis.
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Updated the number of AFP reports received in 2018 and 2019.
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Updated the number of AFP reports received in 2018 and 2019.
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Added 'Protocol for the case note review of reported AFP cases' document.
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Updated number of AFP reports in 2018 and 2019.
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Added latest data and link to Eurosurveillance Vol 24 Issue 6.
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First published.