Cases of norovirus are expected to continue to rise this year, with an estimated 1.19 million people in England already affected by the vomiting bug so far this winter, according to the Health Protection Agency (HPA).

There were more than 4,000 laboratory confirmed cases of the virus in England up to the end of December 2012, a rise of 63 per cent on the same period last year, the HPA said on Tuesday (January 8).

There had been 673 hospital outbreaks reported in England, with 33 outbreaks in the past two weeks.

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	But for each confirmed case there were a further 288 that went unreported as the vast majority of sufferers did not seek medical help, the HPA said.

And, although there had been a downward dip after New Year, the number of cases was expected to rise from now until the end of March, the HPA told C+D.

Meanwhile, cases in Scotland rocketed 70 per cent on the same period the year before, with Health Protection Scotland (HPS) reporting more than 2,800 cases across the country by December 23.

The norovirus has already closed 18 hospital wards in Scotland this season.

HPS epidemiologist Alison Smith-Palmer told C+D the norovirus season had started earlier than in previous years, but there was no indication the number of cases was starting to fall yet.

Testing of the most recent outbreaks revealed that a strain of the virus called Sydney 2012 had become dominant in England and Wales. However, it did not cause more serious illness than other strains, the HPA said.