The number of norovirus outbreaks almost doubled between October and November, according to the Health Protection Agency (HPA).
A highly contagious infection, norovirus activity tends to increase in the winter months and most cases occur between October and April.
As a result of the 43 outbreaks recorded in hospitals, there have been 39 ward closures.
Symptoms include a sudden onset of vomiting, diarrhoea, a temperature, headaches and stomach cramps.
John Harris, a HPA epidemiologist specialising in the virus, commented: "Norovirus comes on fairly suddenly, with little warning and is highly contagious.
"Anyone who thinks they may have it should not to go to their doctor's surgery or A&E as this could spread the illness to vulnerable people and healthcare workers."
He added that this is particularly important in hospitals because there of the risk of ward closures and "severe disruption to hospital services".
Sufferers are advised to take plenty of fluids and allow the illness to run its course, which should not be more than a few days.