NHS organisations in England are playing down the extent of the current outbreak of norovirus infection.

The highly contagious infection, which causes acute vomiting and diarrhoea, has resulted in the closure of some hospital wards across the country, and the number of laboratory confirmed infections is at its highest since 2002.

But a spokeswoman for the Health Protection Agency said that this rise was partly due to the introduction of a more sensitive test for norovirus, which had been rolled out across all testing sites last year.

“The season did start uncharacteristically early this year, with a …