The UK Health Security Agency has declared a national incident after a routine sewage inspection at Beckton Sewage Plant found traces of the polio virus.
Wild polio was last contracted in the UK in 1984. The UK was declared polio-free in 2003.
The Health Security Agency states that the risk to the public is ‘extremely low’.
Between February and May several closely-related polio virus were discovered in sewage samples and these have been classified as a vaccine-derived poliovirus type 2 (VDPV2).
Monitoring of wastewater
According to the Health Security Agency it is quite normal for one to three ‘vaccine-like’ polio virus to be detected in UK sewage samples every year.
These discoveries are one-off findings that disappear.
The current case is of more concern as the VDPV2 strain has continued to evolve. Monitoring of wastewater is being expanded to work out the extent of any transmission and, if necessary, identify local areas for targeted action.
The most likely scenario is that there has been a spread of the virus between members of an extended family somewhere in northeast London and that these people are now shedding the type 2 poliovirus strain in their faeces.
The most concerning aspect of this discovery is how polio, which has almost been completely eradicated worldwide, has somehow managed to find a toehold, however small, in a country with a sophisticated healthcare system and good levels of vaccine coverage.
Check your vaccinations are up to date
On rare occasions the VDPV2 virus can cause serious illness such as paralysis in people who are not fully vaccinated.
Consequently the health authorities are urging people to ensure all their vaccinations are up to date, especially young children under five who are at higher risk.