Frequency of transmission, asymptomatic shedding, and airborne spread of Streptococcus pyogenes among schoolchildren exposed to scarlet fever: a longitudinal multi-cohort molecular epidemiology contact tracing study
Frequency of transmission, asymptomatic shedding, and airborne spread of Streptococcus pyogenes among schoolchildren exposed to scarlet fever: a longitudinal multi-cohort molecular epidemiology contact tracing study
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接触猩红热的学童中化脓性链球菌的传播频率、无症状脱落和空气传播：一项纵向多队列分子流行病学接触追踪研究
DOI：
10.1101/2021.07.04.21259990
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Cordery R
中科院分区：
文献类型：
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作者：
Cordery R
尽管有关于及时治疗病例和加强卫生措施的建议，但2014 - 2018年间英格兰的猩红热疫情有所增加。我们的目的是评估标准干预措施对化脓性链球菌传播的影响ofStreptococcus pyogenesto教室接触者，家庭和教室environment.MethodsWe进行了前瞻性，接触追踪研究，在学校与2个连续的猩红热病例，报告给当地的健康保护小组在伦敦之间3月1日和5月31日在2018年和2019年。我们在四个时间点培养了病例、家庭接触者和教室接触者的咽拭子。我们还对所有病例以及2019年课堂接触者的手拭子和咳嗽板进行了培养。2018年从教室的玩具和其他污染物的表面拭子进行了培养，并于2019年从教室收集了沉降板。任何带有S.结果2018年3月1日至5月31日和2019年同期共招募6个班级，包括12名猩红热病例，17名家庭接触者和278名教室接触者。疫情流行情况。无症状教室接触者咽拭子中化脓性链球菌检出率较高，从第1周的9.6%（11/115）上升到第2周的26.9%（34/126），第3周的24.1%（26/108），第4周的14.3%（5/35）。非爆发和非基因型的定殖。化脓性链球菌感染率分别为1.7%（2/115）、3.9%（5/126）、5.6%（6/108）和0/35。基因组测序显示，在六个类中的每一个内的分离株的克隆性，确认最近的传播占高承载。在进行传递性检测时，emm4和emm3.93无症状携带者的咳嗽平板阳性率分别为1/14（7.1%）和7/21（33.3%）。在3间教室中，仅1/60的表面拭子产生了暴发。化脓性菌株相比之下，2/12和6/12的沉降板放置在高架位置产生爆发。在两间教室里测试化脓性菌株。学校的化脓性传播很严重，可能发生在报告的病例治疗之前或尽管如此，这突出表明需要迅速进行病例管理。尽管遵循指南，但S.少数教室接触者的化脓性链球菌可能使疫情持续，空气传播在传播中可能起作用。研究结果强调了研究的必要性，以提高理解和评估干预措施的有效性，以减少。空气传播
BackgroundDespite recommendations regarding prompt treatment of cases and enhanced hygiene measures, scarlet fever outbreaks increased in England between 2014-2018. We aimed to assess the impact of standard interventions on transmission ofStreptococcus pyogenesto classroom contacts, households, and classroom environments.MethodsWe undertook a prospective, contact tracing study in schools with 2 consecutive scarlet fever cases that were reported to local Health Protection teams in London between March 1stand May 31st in 2018 and 2019. We cultured throat swabs from cases, household contacts, and classroom contacts at four time points. We also cultured hand swabs and cough plates from all cases, and from classroom contacts in 2019. Surface swabs from toys and other fomites in classrooms were cultured in 2018, and settle plates from classrooms were collected in 2019. Any sample withS. pyogenesdetected was recorded as positive and underwentemmgenotyping and genome sequencing to compare with the outbreak strain.FindingsSix classes, comprising 12 scarlet fever cases, 17 household contacts, and 278 classroom contacts were recruited from March 1stto May 31st in 2018 and the same period in 2019. Prevalence of the outbreakS. pyogenesstrain in throat swabs from asymptomatic classroom contacts was high, increasing from 9.6% (11/115) in week 1, to 26.9% (34/126) in week 2, to 24.1% (26/108) in week 3, then 14.3% (5/35) in week 4. Colonisation with non-outbreak and non-genotypedS. pyogenesstrains was 1.7% (2/115); 3.9% (5/126); 5.6% (6/108); and 0/35 in the same weeks. Genome sequencing showed clonality of isolates within each of six classes, confirming recent transmission accounted for high carriage. When transmissibility was tested, children who were asymptomatic carriers ofemm4 andemm3.93 had positive cough plates on 1/14 (7.1%) and 7/21 (33.3%) occasions respectively. Only 1/60 surface swabs taken in 3 classrooms yielded the outbreakS. pyogenesstrain. In contrast, 2/12 and 6/12 settle plates placed in elevated locations yielded the outbreakS. pyogenesstrain in the two classrooms tested.InterpretationS. pyogenestransmission in schools is intense and may occur prior to, or inspite of reported treatment of cases, underlining a need for rapid case management. Despite guideline adherence, heavy shedding ofS. pyogenesby small numbers of classroom contacts may perpetuate outbreaks, and airborne transmission has a plausible role in spread. The findings highlight the need for research to improve understanding and assess effectiveness of interventions to reduceS. pyogenesairborne transmission.