As part of its surveillance for norovirus the Health Protection Agency (HPA) carries out genetic testing of norovirus strains from cases in England and Wales.
Testing carried out when cases started to rise in October revealed a cocktail of different strains that were circulating including Sydney 2012 and another called New Orleans 2009, although no one strain was dominant.
The latest testing of the most recent outbreaks, completed this week, has now shown that Sydney 2012 has overtaken all others to become the dominant strain.
Syndey 2012 was first seen in Australia (and takes its name from the place it was first identified) and has also been seen in France, New Zealand and Japan.
This new strain does not cause more serious illness than others and the methods of managing cases and outbreaks are the same for any strain of norovirus. These measures include washing the hands thoroughly and regularly particularly after using the toilet and before eating.
Dr David Brown, Director of Virology Reference Department at the HPA said, “It is always difficult to predict the norovirus season and this year is no different.
“Noroviruses mutate rapidly and new strains are constantly emerging. At the start of the season it is normal for outbreaks to be caused by a range of different strains. However as the season progresses particular strains are more successful and become dominant. The emergence of a new strain does not mean that it causes more serious illness and managing outbreaks and those will the illness remains the same.
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