Noroviruses are part of a group of viruses that are the most common cause of gastroenteritis (upset stomach) in the UK.
Noroviruses are sometimes known as 'small round structured viruses' (SRSV) or 'Norwalk-like viruses'. Noroviruses are also called the 'winter vomiting disease' because people usually get them during the winter months. However, they can occur at any time of the year.
How noroviruses are spread
It is estimated that the norovirus affects between 600,000 and one million people in the UK every year. Outbreaks of the illness are common, particularly within contained environments such as hospitals, nursing homes and schools. This is because the norovirus spreads very easily from person to person and it can survive for several days in a contaminated area.
The norovirus can be spread through contact with an infected person, through contact with surfaces or objects that are contaminated with the virus, or by eating contaminated food or water.
There are many types of norovirus, and it is possible for infection to occur several times. This is because after getting the illness immunity to the virus only lasts for 14 weeks. Having recurring bouts of the norovirus may provide some protection from future infection.
