U.K. health authorities have said they are urgently investigating a rare polio virus discovery in sewage samples in London, potentially putting Britain's polio-free status at risk for the first time in almost two decades.
A number of waste samples from the Beckton sewage treatment works in Newham, east London tested positive for vaccine-derived polio virus between February and May, the U.K. Health Security Agency said Wednesday.
The virus has since continued to evolve and is now classified as a "vaccine-derived" polio virus type 2, the UKHSA said, adding that it is looking to establish if any community transmission is occurring.
"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," Dr. Vanessa Saliba, consultant epidemiologist at UKHSA, said Wednesday.
Polio is a rare virus that can occasionally cause serious illness, such as paralysis, in people who are not fully vaccinated. The disease was previously common in the U.K. in the 1950s, but the country was declared polio-free in 2003.