[Analysis on risk factors for norovirus outbreaks in Guangdong province, 2008-2015].

Objective To analyze transmission factors of norovirus outbreaks in Guangdong province during 2008-2015 and provide evidence for the prevention and control of norovirus infection. Methods Epidemiological analysis was performed on the data of norovirus outbreaks reported in Guangdong from January 1, 2008 to December 31, 2015, which were obtained from the Public Health Emergency Management Information System of Guangdong province. The samples collected from the norovirus outbreaks were detected for norovirus by RT-PCR and the gene sequencing of the positive PCR products were performed. Results A total of 96 norovirus outbreaks were reported in Guangdong during 2008-2015. Sixteen outbreaks were reported during 2008-2012 and 80 outbreaks were reported during 2013-2015 (83.3%). Eighty-two outbreaks (85.4%) occurred in schools. The infection routes included foodborne transmission in 39 outbreaks (40.6%), person to person transmission in 23 outbreaks (24.0%) and waterborne transmission in 8 outbreaks (7.3%). The gene sequencing results showed that variant GⅡ.4/Sydney2012 was the predominant pathogen for 6 of the 20 outbreaks (30.0%) during 2012-2013. Variant GⅡ.17 was the predominant pathogens for 33 of the 53 outbreaks (62.3%) during 2014-2015. Conclusion The norovirus outbreaks in Guangdong during 2008-2015 were caused by foodborne and person to person transmissions of two emerging variant: GⅡ.4/Sydney2012 and GⅡ.17. Key words: Norovirus; Outbreaks; Epidemiology; Genotype