Jie Ding
Nanjing Municipal Center for Disease ,China
Title: The concurrent circulation of multiple recombinant norovirus genotypes in 2016/17 and 2017/18 epidemic season in Nanjing, China
Biography
Biography: Jie Ding
Abstract
Noroviruses are the most common cause of acute gastroenteritis (AGE) worldwide, remaining a significant public health problem in both high-income countries and developing countries. In 2016/17 norovirus epidemic season, 34 out of 40 AGE clusters/ outbreaks were laboratory-conformed as GII positive, outnumbering the total number of norovirus clusters/ outbreaks in the past 3 epidemic seasons in Nanjing area. The unusual active norovirus activity and the sharp rise in the AGE outbreaks were presumably due to the predominance of an emergent genotype GII.P16/GII.2 and the concurrent circulation of several other genotypes among which GII.P7-GII.6 and GII.P22-GII.5 were rare recombinant strains. The previously predominant novel GII.P17-GII.17 came second as one of the causative genotypes. Altogether 27.5% of the norovirus outbreaks due to GII.P16-GII.2 strains occurred in kindergartens and elementary schools.The intervariant GII.4 recombinant form GII.P4_New Orleans_ 2009/ GII.4_Sydney_2012, which was considered to have the potential to become an epidemic or pandemic variant, had not been detected. In the current 2017/18 winter season, however, the circulating norovirus genotypes which have caused the majority of norovirus AGE outbreaks are GII.P16/GII.2 and GII.Pe-GII.4. In conclusion, we have observed the tendency that multiple genotypes instead of one single predominant variant have been responsible for the seasonal norovirus epidemic since GII.4 decreased its prevalence from 2014 onwards. The novel GII.P17-GII.17 replaced GII.4 in 2014/15 winter season and the emergent GII.P16/GII.2 surpassed the novel GII.P17-GII.17 in 2016/17 winter season. It remains unknown, however, whether the continuous emergence of novel norovirus variants capable of spreading may occur.