Health bosses urged Brits to check their children’s jabs are up to date after picking up signs of the virus being passed between individuals.
Experts have detected the same bug in London sewage samples since April – a clear signal of a community outbreak.
No cases have yet been confirmed in the UK and the UKHSA said samples were found in East and North London.
This, chiefs say ‘suggests it is likely there has been some spread between closely-linked individuals’.
Because of this, they said these cases could be shedding the virus strain in their faeces.