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Polio: UK Health officials ‘urgently’ investigating after rare virus detected in London sewage


Parents in London are being told to ensure their children are up to date with their polio vaccinations. Photo: Luis Miguel Carceller Palanca

Parents in London are being told to ensure their children are up to date with their polio vaccinations. Photo: Luis Miguel Carceller Palanca

Parents in London are being told to ensure their children are up to date with their polio vaccinations. Photo: Luis Miguel Carceller Palanca

A national incident has been declared in the UK after a rare type of poliovirus was detected in wastewater in London, with health officials racing to determine the scale of a feared outbreak.

The virus, which can cause paralysis and death in rare cases, was identified in sewage samples taken from the capital between February and May 2022, according to the UK Health Security Agency.

UKHSA said it was “likely” there has been spread of a vaccine-derived poliovirus type 2 (VDPV2) between closely linked people in north-east London, with infected individuals believed to be shedding the virus in their faeces.

The agency is now “urgently” investigating whether wider transmission of the infection, which can spread without symptoms in low-vaccinated communities, is occurring in the capital. So far, no suspected cases have been reported or confirmed.

The rise of VDPV2s throughout the globe is threatening attempts to eradicate polio. They are a rare, mutated version of the virus — typically found in under-immunised communities with poor sanitation — which derive from the live oral polio vaccine (OPV).

People vaccinated with OPV, which has not been used in Britain since 2004, can briefly shed traces of the vaccine-like poliovirus in their faeces. Samples of this kind are detected up to three times a year in UK sewage, likely from peopled inoculated overseas, and are considered normal, the UKHSA said.

However, after several closely related viral samples were found earlier this year in sewage taken from London Beckon Sewage Works, which covers four million people across the north-east of the capital, the virus appears to have spread and further evolved into a VDPV2, the agency said.

Infected individuals in the capital are now shedding the type 2 poliovirus strain in their faeces, UKHSA added.

Health officials said the VDPV2 has the potential to spread in communities with low vaccine coverage, and urged people and children who are not fully vaccinated to contact a GP.

So far, there have been no associated cases of polio-related paralysis, which occurs in up to 1pc of infections. Most people who contract the virus will not develop any visible symptoms. UKHSA said the risk to the public is “extremely low”.

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Dr Vanessa Saliba, a consultant epidemiologist at UKHSA, said: “Most of the UK population will be protected from vaccination in childhood, but in some communities with low vaccine coverage, individuals may remain at risk.

“We are urgently investigating to better understand the extent of this transmission and the NHS has been asked to swiftly report any suspected cases to the UKHSA, though no cases have been reported or confirmed so far.”

Jane Clegg, chief nurse for the NHS in London, said health officials will begin contacting parents of children aged under five who are not up-to-date with their polio vaccinations.

“The majority of Londoners are fully protected against polio and won’t need to take any further action,” she added.

The last case of wild polio contracted in the UK was confirmed in 1984 and the UK was declared free of the virus in 2003. Afghanistan and Pakistan are the only two countries in the world where the infection is still classified as endemic.

In response to the outbreak, wastewater surveillance is being expanded to assess the extent of transmission and identify local areas for targeted action.

Healthcare professionals have been told to investigate and report anyone presenting with symptoms that could be polio. While the majority of patients won’t display symptoms, one in four will develop a flu-like illness three to 21 days after infection. Symptoms can include fever, nausea and stomach pain.

In exceptionally rare cases, poliovirus attacks the nerves in the spine and base of the brain of an infected individual. This can cause paralysis, usually in the legs, that develops over hours or days. If the breathing muscles are affected, it can be life threatening. Up to 10pc of people who develop paralysis from polio die.

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