Ten wards at York Hospital have been affected by the Norovirus. Five wards are closed due to the spread of the stomach bug. Visitors who are unwell are being asked not to visit their friends and relatives.
The bug is highly infectious and can be spread by hand to hand contact. The hospital are taking measures to prevent further ward closures.
Latest figures from the Health Protection Agency (HPA) show there has been a 72% increase in the number of cases reported at the same point last year.
The HPA have seen 3,877 laboratory confirmed cases of norovirus this season (from week 27 to week 51 2012).
Cases of norovirus have risen earlier than expected this winter season and this is a trend that has been seen across Europe and other parts of the world. It has not yet been determined why this has been the case and activity varies significantly from year to year.
During the two weeks up to 30 December there were 29 hospital outbreaks reported, compared to 70 in the previous fortnight, bringing the total of outbreaks for the season to 590
John Harris, an expert in norovirus from the HPA said:
As we have seen in previous years there has been a dip in the number of confirmed laboratory reports owing to the Christmas and New Year period. However, in line with other norovirus seasons we will expect to see an increase in the number of laboratory reports in the next few weeks.
Norovirus is very contagious, and anyone who has had it knows it is very unpleasant. If you think you may have the illness then it is important to maintain good hand hygiene to help prevent it spreading. We also advise that people stay away from hospitals, schools and care homes as these environments are particularly prone to outbreaks.
The Health Protection Agency (HPA) has warned that for every confirmed case of the stomach bug, there are likely to be a further 288 unreported sufferers.
There have been 2,630 confirmed cases so far this season, meaning that the real number could be 757,440.
A spokesperson for the HPA said: "Laboratory confirmed reports represent only a small proportion of the actual amount of norovirus activity in the community, because the vast majority of affected people do not access health care services as a result of their illness."