Molecular etiologic investigation of gastroenteritis outbreaks caused by Norovirus GⅠ in two schools in Lanzhou, 2018

ObjectiveTo understand the molecular characteristics of Norovirus-caused outbreaks of acute gastroenteritis in two schools in Lanzhou from May to June in 2018, and analyze the sources of Norovirus infections.

MethodsTwenty nine anal swabs and 4 surface swabs from the two outbreaks were detected for Norovirus by real-time fluorescence quantitative RT-PCR. The RdRp and VP1 region genes of positive samples were sequenced and analyzed by NCBI and MEGA 6.0 software.

ResultsThe outbreaks of gastroenteritis in two schools were caused by Norovirus GⅠ. In the outbreak in school A from 28 May to 4 June, 50 cases occurred with an attack rate of 3.24%. In the outbreak in school B from 1 to 13 June, 35 cases occurred with an attack arte of 4.76%. The epidemiological investigation showed that the two outbreaks were related to small dining place and close contact. Thirteen out of 33 samples were positive for Norovirus GⅠ nucleic acid. The gene sequencing and alignment results indicated that the first epidemic was caused by Norovirus GⅠ.3 P13, and the second one was caused by Norovirus GⅠ.6 P11.

Conclusion Two outbreaks of acute gastroenteritis in two schools in Chengguan district of Lanzhou were caused by Norovirus GⅠ.3 P13 and GⅠ.6 P11 respectively. It is necessary to strengthen the surveillance for Norovirus and the management of small dining places near middle and primary schools.