Abstract：Objective To analyze the epidemiological characteristics and the genotypes of pathogens in an outbreak of noroviru-induced infectious diarrhea in a primary school, to explore the possible route of transmission so as to provide scientific evidence for effective prevention and control of the epidemic as well as simultaneously provide experience for on-site disposal of the similar epidemic. Methods The uniform case definition was formulated, and the initiative case research was conducted among the students and teaching staff of the school. Descriptive epidemiological approaches and retrospective cohort study were used to identify the risk factors. Vomit and stool or anal swab samples were collected from patients without treatment. Anal swabs from the kitchen workers, drinking water samples from the classes and the environmental surface samples from the kitchen and involved classrooms were also collected. Real-time fluorescent quantitative PCR was used to detect norovirus nucleic acid, and the positive samples were amplified by RT-PCR. The PCR amplification products were purified, sequenced and then compared with sequences in GenBank. The sequences were aligned by Clustal X employing MEGA 5.1 program package to construct the phylogenetic trees. The database was established by Excel 2010 software, and then analyzed by Open Epi software version 3.0.3 online. Results A total of 36 cases were reported in the school from November 18th to 24th, 2014. The peak incidence was on November 19th (n=19). Grade 2 Class 3 had the highest attack rate (55.81%, 24/43), followed by Grade 2 Class 10 (14.29%, 6/42). The main symptoms included vomit (97.22%), fever (38.89%), abdominal pain (36.11%) and diarrhea (8.33%). The retrospective cohort study revealed that participating in dancing class was the risk factor for the incidence (RR=6.67, P<0.01). 6 out of 16 samples from the cases were found norovirus positive by real-time fluorescent quantitative PCR. The sequence alignment showed that the nucleotide sequence homology of the 6 viral stains was 100%, and they shared 98% homogeneity with GII.P17_GII.17/Kawasa-ki323 and GII.17/Okinawa/FP027/2012 strain, indicating these viruses were homologous and belonged to the GⅡ. 17 norovirus strain. Conclusion The outbreak of GII.17 norovirus-induced infectious diarrhea in the school is caused by close contact.
宋灿磊,刘天,杜荐如,朱建明. 金山区某学校一起诺如病毒感染性腹泻疫情流行病学调查[J]. 实用预防医学, 2017, 24(4): 429-432.
SONG Can-lei, LIU Tian, DU Jian-ru, ZHU Jian-ming. Epidemiological investigation on an outbreak of norovirus-induced infectious diarrhea in a primary school in Jinshan Dstrict. , 2017, 24(4): 429-432.
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