The country has been placed on alert after polio was detected in London sewage despite the country having been free of it since 2003.
The UK Health and Security Agency said it is investigating after poliovirus samples were found at London Beckton Sewage Treatment Works.
It is working with the Medicines and Healthcare products Regulatory Agency (MHRA) to get on top of the outbreak, with the last case of wild polio being confirmed in 1984.
The virus, which has now been classified as ‘vaccine-derived’, was found during routine checks conducted between February and May this year. The UKHSA said it is “likely there has been some spread” between closely linked people in north and east London.
“Vaccine-derived poliovirus is rare and the risk to the public overall is extremely low”, said Dr Vanessa Saliba, Consultant Epidemiologist at UKHSA.
“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”, she added.
“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.”