UK On Alert After Polio Virus Detected In London Sewage Samples

The United Kingdom has gone on alert after the detection of polio virus strains from a London sewage plant.

Model of a polio virus capsid (the green spherical organism) binding to polio virus receptors (the protruding multicoloured molecules.)

(Photo: iStock)

The World Health Organisation (WHO) and British health authorities said that a type of polio virus has been detected in London sewage samples, in a statement on Wednesday, 22 June.

"The Global Polio Laboratory Network (GPLN) has confirmed the isolation of type 2 vaccine-derived poliovirus (VDPV2) from environmental samples in London, United Kingdom (UK), which were detected as part of ongoing disease surveillance."

WHO statement

It is important to note that the virus has been isolated from environmental samples only – no associated cases of paralysis have been detected.

Why Is This a Matter of Concern?

In a report, the UK Health Security Agency (UKHSA) said, "Multiple sewage samples collected from the London Beckton Sewage Treatment Works between February and June 2022 show isolated strains of the virus."

This particular plant covers a large part of north and east London, and is home to about four million people.

Polio is a dangerous disease, that can even cause paralysis in humans.

(Photo: iStock)

As part of routine surveillance, it is normal for 1 to 3 ‘vaccine-like’ polioviruses to be detected each year in UK sewage samples but these have always been one-off findings that were not detected again. This time, however, several strains have been found.

These findings are concerning because prior to this one, when strains of the polio virus had been found, they were unrelated.

In this case, the health authorities warned that the strains were genetically related.

"There may be localised spread of polio virus, most likely within individuals that are not up to date with polio immunisations".

Dr Kathlene O'Reilly, Associate Professor of Statistics for Infectious Disease & Polio Eradication Expert

Vaccination Histories and Why They Are Important

There are two forms of Polio Vaccine, OPV and IPV.

OPV which is the Oral Polio Vaccine, uses a form of weakened but live polio virus that can replicate in the gut and be passed to others through faecal-contaminated water, putting their neighbors in danger of the infection.

UK had stopped using this vaccine and switched to Inactive Polio Virus (IPV).

Thus, it is suspected that some family who has just shifted to the UK might have received the OPV and is now 'shedding' virus strains.

Dr Vanessa Saliba, Consultant Epidemiologist at UKHSA, was found saying, 'Vaccine-derived poliovirus is rare and the risk to the public overall is extremely low.'

Oral Polio Vaccine is a live attenuated vaccination made up of living poliovirus.

(Photo: iStock)

'Vaccine-derived poliovirus has the potential to spread, particularly in communities where vaccine uptake is lower. On rare occasions it can cause paralysis in people who are not fully vaccinated so if you or your child are not up to date with your polio vaccinations it’s important you contact your GP to catch up or if unsure check your Red Book.

Dr Vanessa Saliba, Consultant Epidemiologist, UKHSA

The last case of wild polio contracted in the UK was confirmed in 1984. The UK was declared polio-free in 2003.

The majority of London demonstrates an immunization coverage of 86.6%. Regardless, healthcare professionals have been alerted to these findings so they can promptly investigate and report anyone presenting with symptoms that could be polio, such as paralysis.

Further analysis is underway to check for community transmission of the virus.