Analysis of molecular characteristics of aggregation epidemic induced by norovirus infection in Hebei province, 2015-2016

Objective To understand epidemiological characteristics of the pathogens and evolution of the genotype associated with infectious diarrhea epidemic caused by norovirus in Hebei Province. Methods A total of 8 infectious diarrhea outbreaks caused by norovirus were reported from Jan 2015 to Dec 2016, of which epidemic treatment materials and specimens were collected at the same time. Norovirus nucleic acid was detected by using real-time PCR, and the partial ORF2 of the all positive specimens were amplified by RT-PCR and sequenced. Phylogenetic tree was constructed by using Mega5.2 based on partial ORF2 sequences of norovirus to perform phylogenetic analysis. Results A total of 8 norovirus outbreaks, involving 265 cases who were mainly for residential inhabitents, children and students, were reported during this period, and the overall attack rate ranged from 0.70% to 8.13%. The overall positive detection rate of norovirus was 66.25%. The PCR products were sequenced, and sequencing result were obtained for 28 samples, which included GⅠ.3, GⅡ.2, GⅡ.4, GⅡ.13 and GⅡ.17. Conclusions Multiple genotypes of infectious diarrhea outbreaks caused by norovirus were found in Hebei province. Key words: Norovirus; Outbreaks; Genotypes; Molecular characteristics