Epidemiological characteristics of outbreaks of norovirus-G Ⅱ.2, G Ⅱ.17 and G Ⅱ.4/Sydney in Guangdong province, 2013-2017 / 中华流行病学杂志

ABSTRACT

Objective To understand the epidemiologic characteristics of outbreaks,caused by norovims-G Ⅱ.2、G Ⅱ.17 and G Ⅱ.4/Sydney in Guangdong Province from 2013 to 2017 and to provide scientific evidence for epidemic prevention and control.Methods Incidence data of norovirus outbreaks in Guangdong from January 1st 2013 to November 30th 2017 were collected from Public Health Emergency Management Information System.RT-PCR was performed for every case of each outbreak to detect norovirus nucleic acid and gene sequencing was conducted to identify the genotype of norovirus.Characteristics of norovirus G Ⅱ.2,G Ⅱ.17 and G Ⅱ.4/Sydney outbreaks were analyzed.Directly standardized method was used to calculate the proportion of symtoms as diarrhea and vomitting.Results From January 1st 2013 to November 30th 2017,a total of 167 norovirus outbreaks were reported in Guangdong,and 115 outbreaks were caused by norovirus G Ⅱ.2,G Ⅱ.17 and G Ⅱ.4/Sydney respectively.The outbreaks caused by norovirus G Ⅱ.2 accounted for 39.68％ (25/63) in primary schools,28.57％ (18/63) in child care settings,25.40％ (16/63) in middle schools and 6.35％ (4/63) in universities.Outbreaks caused by norovirus G Ⅱ.17 accounted for 41.03％ (16/39) in middle schools,20.51％ (8/39) at workplaces,15.38％ (6/39) in primary schools,12.82％ (5/39) in universities,5.13％ (2/39) in communities and child care settings respectively.The outbreaks caused by norovirus G Ⅱ.4/Sydney accounted for 53.85％ (7/13) in universities,15.38％ (2/13) in child care settings and at workplaces respectively,7.69％ (1/13) in primary schools and middle schools respectively.The outbreaks caused by norovirus G Ⅱ.2 had 77.78％ (49/63) of contact transmission,17.46％ (11/63) of food-borne transmission.The outbreaks caused by norovirus G Ⅱ.17 showed 53.85％ (21/39) of food-borne transmission,15.38％ (6/39) of contract transmission,12.82％ (5/39) of water-borne transmission.The outbreaks caused by norovirus G Ⅱ.4/Sydney had 53.85％ (7/13) of food-borne transmission,38.46％ (5/13) of the contact transmission.In terms of the clinical manifestations,the standardized proportion of vomit was 73.76％ and the proportion of diarrhea was 42.85％ in cases infected with norovirus G Ⅱ.2,the proportion of standardized of vomit was 76.37％ and the proportion of diarrhea was 51.40％ in cases infected with norovirus G Ⅱ.17,with the standardized proportion of vomit was 54.10％ and the proportion of diarrhea was 55.95％ in cases infected with norovirus G Ⅱ.4/Sydney.Conclusions The outbreaks caused by norovirus G Ⅱ.2 through contact transmission mainly occurred in primary schools,child care settings and middle schools.The outbreaks caused by norovirus G Ⅱ.17 through food-borne transmission mainly occurred in middle schools and at workplaces.The outbreaks caused by norovirus G Ⅱ.4/Sydney food-borne transmission and contact mainly occurred in universities.