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[Outbreaks of noroviral gastroenteritis and their molecular characteristics in China, 2006 - 2007].

OBJECTIVE
To acknowledge the epidemiology of gastroenteritis outbreaks caused by noroviruses and their genotypes.


METHODS
Epidemiologic data and specimens were collected from 19 gastroenteritis outbreaks. 201 specimens were detected for norovirus, rotavirus, astrovirus, adenovirus and sapovirus by RT-PCR methods and PCR products were sequenced. Sequence alignment and phylogenetic analysis were performed by Clustal X 1.83 and MEGA 4.0 programs.


RESULTS
Noroviruses were one of the most predominant pathogens causing viral gastroenteritis outbreaks (12 of 19 outbreaks, accounting for 63.2%). Variant GII-4/2006b was the predominant strain responsible for 11 of the 12 NV-associated outbreaks. Other genotypes would include GII-17, GII-6 and GII-3. The NV-associated gastroenteritis outbreaks occurred mainly in winter and spring between December 2006 and April 2007. These gastroenteritis outbreaks caused by noroviruses would involve all age groups in various locations. Meantime, 2 out of 12 outbreaks were caused by norovirus or other viruses. In addition, multiple viruses and multiple genotypes of noroviruses were found in the same outbreak.


CONCLUSION
Noroviruses were one of the most major pathogens causing gastroenteritis outbreaks while GII-4/2006b variant was identified as the predominant strain in China.