感染诺如病毒的托幼儿童和中小学生排毒时长研究

Viral shedding in day-care children and students infected with norovirus in outbreaks

【目的】评估托幼机构和中小学诺如病毒疫情期间,感染诺如病毒儿童排毒时长及影响排毒时长的可能因素,为疫情防控提供科学依据。【方法】2017—2019年,采集上海市徐汇区托幼机构和中小学校诺如病毒疫情疑似病例及密切接触者标本,应用实时荧光定量逆转录聚合酶链反应(real-time RT-PCR)方法检测样本诺如病毒带毒情况。对感染诺如病毒儿童经知情同意后每隔3~7 d采样,直至样本检测阴性。【结果】研究期间,共报告76起诺如病毒感染聚集性疫情,涉及1014例疑似病例,对421名疑似病例标本检测,诊断出311名确诊病例。经知情同意后,共有58名确诊病例参与排毒研究,参与率为18.65%。诺如病毒感染者平均排毒时间为(16.24±13.80)d,排毒时间超过7 d病例占79.31%,超过14 d占37.93%,超过21 d占17.24%。Cox比例风险模型结果显示,症状较严重者(HR=2.06,P=0.040)、托幼儿童病例(HR=4.13,P=0.012)和2019年确诊病例(HR=0.11,P<0.001)排毒时间更长。【结论】感染诺如病毒的学龄儿童返校后的一段时间内仍存在持续排毒,从而导致疫情传播风险,建议在病例返校后做好排泄物的消毒处理,避免疫情的二次传播和蔓延。

[Objective]This study aimed to investigate the time duration of norovirus shedding among day-care children and students during norovirus outbreaks,as well as influencing factors affecting the viral shedding.[Methods]Suspected cases of norovirus infection and their close contacts were collected from child care and school settings during norovirus outbreaks in Xuhui District,Shanghai,from 2017 through 2019.Specimens were detected using real-time RT-PCR to determine whether children had been infected with norovirus.Subsequently,further specimens were collected every 3-7 days from infected children until specimens tested negative for norovirus.[Results]A total of 76 outbreaks were reported involving 1014 suspected cases.In the 421 suspected cases,311 confirmed cases were diagnosed after examination.Furthermore,a total of 58 confirmed cases participated in this study with informed consent,with a participation rate of 18.65%.The average time duration of norovirus shedding was(16.24±13.80)days,in which 79.31%had viral shedding more than 7 days,37.93%more than 14 days and 17.24%more than 21 days.A Cox proportional-hazards model showed that children with more severe symptoms(HR=2.06,P=0.040),day-care children(HR=4.13,P=0.012),and confirmed cases in 2019(HR=0.11,P<0.001)had longer duration of viral shedding.[Conclusion]Children may remain shedding norovirus after their recovery and back to class.Improvement in sanitation for these recovered children in child care and schools is especially necessary,which may avert secondary transmission.