Frequency of transmission, asymptomatic shedding, and airborne spread of Streptococcus pyogenes in schoolchildren exposed to scarlet fever: a prospective, longitudinal, multicohort, molecular epidemiological, contact-tracing study in England, UK.
Frequency of transmission, asymptomatic shedding, and airborne spread of Streptococcus pyogenes in schoolchildren exposed to scarlet fever: a prospective, longitudinal, multicohort, molecular epidemiological, contact-tracing study in England, UK.
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DOI：
10.1016/s2666-5247(21)00332-3
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发表时间：
2022-05
期刊：
影响因子：
38.2
通讯作者：
Sriskandan, Shiranee
中科院分区：
文献类型：
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作者：
Cordery, Rebecca;Purba, Amrit K.;Begum, Lipi;Mills, Ewurabena;Mosavie, Mia;Vieira, Ana;Jauneikaite, Elita;Leung, Rhoda C. Y.;Siggins, Matthew K.;Ready, Derren;Hoffman, Peter;Lamagni, Theresa;Sriskandan, Shiranee
尽管有关于及时治疗病例和加强卫生措施的建议，但2014年至2018年期间，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向教室接触者、家庭和教室环境传播的影响，以提供未来的指导。我们在英国大伦敦的五所学校的六个环境中进行了一项前瞻性、纵向、多队列、分子流行病学、接触者追踪研究。学校和托儿所如果在10天内报告了同一班级2-8岁儿童的两起猩红热病例，并且最近的病例发生在前48小时内，则有资格参加。我们在四个时间点培养了猩红热儿童、教室接触者和家庭接触者的咽拭子。我们还培养了第1年和第2年研究中所有病例的手拭子和咳嗽板，以及第2年课堂接触的手拭子和咳嗽板。在第1年培养教室中玩具和其他污染物的表面拭子，并在第2年收集教室中的沉降板。所有检测到化脓性链球菌的样本均记录为阳性，并进行emm基因分型和基因组测序，以与暴发菌株进行比较。在2018年3月1日至5月31日（第一年）和2019年3月1日至5月31日（第二年）期间招募了6个班级，包括12例猩红热病例，17例家庭接触者和278例教室接触者。无症状的喉咙携带爆发菌株的人数从第1周的115名拭子儿童中的11人（10%）增加到第2周的126名儿童中的34人（27%），再到第3周的108名儿童中的26人（24%），然后是第4周的5人（14%）35人。与携带爆发性化脓性链球菌菌株相比，在第1周，115名拭子儿童中有2名（2%）发生了非爆发性和非基因型化脓性链球菌菌株的定植，第2周，126名拭子儿童中有5名（4%），第3周，108名拭子儿童中有6名（6%），在第4周，35名儿童中无一例发生（整个研究的中位携带率为2.8%[IQR 0.0 - 6.6]）。基因组测序显示，在六个类别的每一个爆发分离株的克隆性，证实最近的传播占高承载。当测试传染性时，11名emm 4无症状携带者中的1名（9%）和14名emm3.93无症状携带者中的5名（36%）咳嗽平板呈阳性。从三间教室采集的60份表面拭子中仅发现一份（2%）爆发菌株;然而，在两间将沉降板放置在高架位置的教室中，12个沉降板中的两个（17%）和12个沉降板中的六个（50%）产生了爆发菌株。化脓性链球菌在学校的传播很严重，可能发生在报告的病例治疗之前或之后，强调需要快速病例管理。尽管遵守了指导方针，但少数课堂接触者大量脱落的化脓性链球菌可能会使疫情持续下去，空气传播在其传播中起着似乎合理的作用。这些发现强调了研究的必要性，以提高认识和评估干预措施的有效性，以减少空气传播的化脓性链球菌。行动医学研究，英国研究创新和国家健康研究所。
Despite recommendations regarding prompt treatment of cases and enhanced hygiene measures, scarlet fever outbreaks increased in England between 2014 and 2018. We aimed to assess the effects of standard interventions on transmission of Streptococcus pyogenes to classroom contacts, households, and classroom environments to inform future guidance. We did a prospective, longitudinal, multicohort, molecular epidemiological, contact-tracing study in six settings across five schools in Greater London, UK. Schools and nurseries were eligible to participate if they had reported two cases of scarlet fever within 10 days of each other among children aged 2–8 years from the same class, with the most recent case arising in the preceding 48 h. We cultured throat swabs from children with scarlet fever, classroom contacts, and household contacts at four timepoints. We also cultured hand swabs and cough plates from all cases in years 1 and 2 of the study, and from classroom contacts in year 2. Surface swabs from toys and other fomites in classrooms were cultured in year 1, and settle plates from classrooms were collected in year 2. Any sample with S pyogenes detected was recorded as positive and underwent emm genotyping and genome sequencing to compare with the outbreak strain. Six classes, comprising 12 cases of scarlet fever, 17 household contacts, and 278 classroom contacts were recruited between March 1 and May 31, 2018 (year 1), and between March 1 and May 31, 2019 (year 2). Asymptomatic throat carriage of the outbreak strains increased from 11 (10%) of 115 swabbed children in week 1, to 34 (27%) of 126 in week 2, to 26 (24%) of 108 in week 3, and then five (14%) of 35 in week 4. Compared with carriage of outbreak S pyogenes strains, colonisation with non-outbreak and non-genotyped S pyogenes strains occurred in two (2%) of 115 swabbed children in week 1, five (4%) of 126 in week 2, six (6%) of 108 in week 3, and in none of the 35 children in week 4 (median carriage for entire study 2·8% [IQR 0·0–6·6]). Genome sequencing showed clonality of outbreak isolates within each of six classes, confirming that recent transmission accounted for high carriage. When transmissibility was tested, one (9%) of 11 asymptomatic carriers of emm4 and five (36%) of 14 asymptomatic carriers of emm3.93 had a positive cough plate. The outbreak strain was identified in only one (2%) of 60 surface swabs taken from three classrooms; however, in the two classrooms with settle plates placed in elevated locations, two (17%) of 12 and six (50%) of 12 settle plates yielded the outbreak strain. Transmission of S pyogenes in schools is intense and might occur before or despite reported treatment of cases, underlining a need for rapid case management. Despite guideline adherence, heavy shedding of S pyogenes by few classroom contacts might perpetuate outbreaks, and airborne transmission has a plausible role in its spread. These findings highlight the need for research to improve understanding and to assess effectiveness of interventions to reduce airborne transmission of S pyogenes. Action Medical Research, UK Research Innovation, and National Institute for Health Research.