Wednesday, January 2, 2013.

More than one million people in England and Wales have been affected by the vomiting bug known as norovirus, according to the latest figures from the Health Protection Agency (HPA).

The HPA figures show there have been 3,538 laboratory confirmed cases of norovirus this season (from week 27 to week 50 2012), up from 3,046 cases last week. The latest figures are 83 percent higher than the number of cases reported at this point last year.

During the two weeks up to 23 December there were 70 hospital outbreaks reported, compared to 61 in the previous fortnight, bringing the total of outbreaks for the season to 538.

The distribution of norovirus cases across the season varies significantly from year to year, but the number of cases has risen earlier than expected this year. It has not yet been determined why this has been the case, but it is a trend that has been seen across Europe and other parts of the world.

John Harris, an expert in norovirus from the HPA said: “The number of laboratory confirmed cases has risen once again as it appears that we have seen the rise in cases that usually begins in January start a little earlier than we normally expect.

“Norovirus is very contagious, and very unpleasant. To help prevent spread of the disease, it’s important that people who believe they are unwell with the virus maintain good hand hygiene and stay away from hospitals, schools and care homes, as these closed environments are particularly prone to outbreaks which can cause severe disruption.”

But the Department of Health in England said 2.4% of beds were closed in the NHS due to norovirus symptoms compared with a peak of 2.9% last year.

A spokesperson said: "The NHS is well prepared for the winter. No A&Es have had to close so far this winter and we are providing additional funding to the NHS to help it cope with the added pressure that the winter brings."

The Health Protection Agency is an independent UK organisation that was set up by the government in 2003 to protect the public from threats to their health from infectious diseases and environmental hazards.

Norovirus can be transmitted by contact with contaminated surfaces or objects, by contact with an infected person, or by the consumption of contaminated food or water. Symptoms of norovirus include a sudden onset of vomiting and/or diarrhoea. Some people may have a temperature, headache and stomach cramps. The illness usually resolves in one or two days and there are no long-term effects.