Sewage sampling for polio expands beyond London

Sewage sampling has been expanded nationally to areas that are at highest risk of new poliovirus importations and most likely to see spread of poliovirus

Monitoring for the polio virus in sewage has been expanded outside of London by the UK Health Security Agency (UKHSA) as a precautionary measure.

Polio was first detected in sewage samples from London via the World Health Organisation (WHO) Global Polio Laboratory Network (GPLN), but to-date no human case of polio has been reported in the UK.

So far testing has only been carried out in London and Glasgow, though no polio has been detected in the latter. Surveillance has been expanded to sewage treatment works across the UK to determine whether the virus is spreading.

Areas being tested will include parts of Birmingham, Blackburn with Darwen, Bradford, Brighton and Hove, City of Bristol, Bury, Castle Point, Leeds, Leicester, Liverpool, Luton, Manchester, North Tyneside, Newcastle upon Tyne, Gateshead, Nottingham, Preston, Salford, Sheffield and Watford.

Polio is highly infectious and predominantly affects children under five, causing permanent paralysis in approximately one in 200 infections, or death in five to 10% of those paralysed. The disease is transmitted person-to-person most commonly through the faecal-oral route and less commonly via another vehicle such as contaminated water or food.

Dr Vanessa Saliba, Consultant Epidemiologist at UKHSA said, “For the majority of the population, who are fully vaccinated, the risk is low”.

She added: “We are now expanding the sewage sampling nationally to areas that are at highest risk of new poliovirus importations and areas most likely to see spread of poliovirus from London. We are in touch with public health colleagues in these areas and will work closely with local areas as the need arises.”

Saliba also urged parents across the country to ensure their children are fully vaccinated.

The Joint Committee on Vaccination and Immunisation (JCVI) has said all children aged one to nine in London should have a dose of polio vaccine now, whether that be an extra booster or a catch up dose. This will protect against paralysis and help stop the virus spreading.

The polio virus detected in London has originated from someone that has had an oral vaccine outside of the UK, as this vaccine is no longer offered here.

Results and analysis from the expanded UK testing will be available at the earliest in October. Global surveillance has determined that the polio isolates (little pieces of polio virus) detected in London are genetically similar to those found in the US and Israel. Work is being carried out to understand how they are linked.

Scientists have confirmed that the polio virus detected in London has originated from someone that has had an oral vaccine outside of the UK, as this vaccine is no longer offered here.

The oral polio vaccination involves using a small amount of live virus, so it can result in some shedding, which can help boost immunity within a population but also creates a small possibility for it to be transmittable.

Over time as the virus moves about, it mutates, and if enough changes occur it stops being “vaccine like” which is not concerning, and becomes “vaccine derived” which is worrisome as it can then behave more like a wild polio virus.

Both vaccine-like and vaccine-derived isolates were detected in the London sampling.

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