Kittayapong Pattamaporn, Olanratmanee Phanthip, Maskhao Pongsri, Byass Peter, Logan James, Tozan Yesim, Louis Valérie, Gubler Duane J, Wilder-Smith Annelies
Center of Excellence for Vectors and Vector-Borne Diseases, Faculty of Science, Mahidol University at Salaya, Nakhon Phatom, Thailand.
Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand.
PLoS Negl Trop Dis. 2017 Jan 19;11(1):e0005197. doi: 10.1371/journal.pntd.0005197. eCollection 2017 Jan.
Viral diseases transmitted via Aedes mosquitoes are on the rise, such as Zika, dengue, and chikungunya. Novel tools to mitigate Aedes mosquitoes-transmitted diseases are urgently needed. We tested whether commercially insecticide-impregnated school uniforms can reduce dengue incidence in school children.
We designed a cluster-randomised controlled trial in Thailand. The primary endpoint was laboratory-confirmed dengue infections. Secondary endpoints were school absenteeism; and impregnated uniforms' 1-hour knock-down and 24 hour mosquito mortality as measured by standardised WHOPES bioassay cone tests at baseline and after repeated washing. Furthermore, entomological assessments inside classrooms and in outside areas of schools were conducted.
We enrolled 1,811 pupils aged 6-17 from 5 intervention and 5 control schools. Paired serum samples were obtained from 1,655 pupils. In the control schools, 24/641 (3.7%) and in the intervention schools 33/1,014 (3.3%) students had evidence of new dengue infections during one school term (5 months). There was no significant difference in proportions of students having incident dengue infections between the intervention and control schools, with adjustment for clustering by school. WHOPES cone tests showed a 100% knock down and mortality of Aedes aegypti mosquitoes exposed to impregnated clothing at baseline and up to 4 washes, but this efficacy rapidly declined to below 20% after 20 washes, corresponding to a weekly reduction in knock-down and mosquito mortality by 4.7% and 4.4% respectively. Results of the entomological assessments showed that the mean number of Aedes aegypti mosquitoes caught inside the classrooms of the intervention schools was significantly reduced in the month following the introduction of the impregnated uniforms, compared to those collected in classrooms of the control schools (p = 0.04).
Entomological assessments showed that the intervention had some impact on the number of Aedes mosquitoes inside treatment schools immediately after impregnation and before insecticidal activity declined. However, there was no serological evidence of protection against dengue infections over the five months school term, best explained by the rapid washing-out of permethrin after 4 washes. If rapid washing-out of permethrin could be overcome by novel technological approaches, insecticide-treated clothes might become a potentially cost-effective and scalable intervention to protect against diseases transmitted by Aedes mosquitoes such as dengue, Zika, and chikungunya.
ClinicalTrials.gov NCT01563640.
通过伊蚊传播的病毒性疾病正在增加，如寨卡病毒、登革热和基孔肯雅热。迫切需要新的工具来减轻伊蚊传播疾病的影响。我们测试了市售的浸有杀虫剂的校服是否能降低学童的登革热发病率。
我们在泰国设计了一项整群随机对照试验。主要终点是实验室确诊的登革热感染。次要终点是学校缺勤率；以及通过标准化的世界卫生组织杀虫剂评价计划（WHOPES）生物测定锥试验在基线和反复洗涤后测量浸有杀虫剂校服的1小时击倒率和24小时蚊虫死亡率。此外还在教室内部和学校外部区域进行了昆虫学评估。
我们招募了来自5所干预学校和5所对照学校的1811名6-17岁的学生。从1655名学生中获取了配对血清样本。在对照学校，24/641（3.7%）的学生，在干预学校33/1014（3.3%） 的学生在一个学期（5个月）中有新的登革热感染证据。在校间聚类调整后，干预学校和对照学校中发生登革热感染的学生比例没有显著差异。WHOPES锥试验显示，在基线和多达4次洗涤后，接触浸有杀虫剂衣服的埃及伊蚊的击倒率和死亡率均为100%，但在20次洗涤后，这种效果迅速下降至20%以下，相当于每周击倒率和蚊虫死亡率分别下降4.7%和4.4%。昆虫学评估结果显示，与对照学校教室中收集的蚊子相比，在引入浸有杀虫剂校服后的一个月内，干预学校教室中捕获的埃及伊蚊平均数量显著减少（p = 0.04）。
昆虫学评估表明，干预措施在浸渍后且杀虫活性下降之前对治疗学校内的伊蚊数量有一定影响。然而，在五个月的学期中，没有血清学证据表明对登革热感染有保护作用，这最好的解释是在4次洗涤后氯菊酯迅速被洗去。如果可以通过新的技术方法克服氯菊酯的快速洗脱问题，经杀虫剂处理的衣服可能成为一种潜在的具有成本效益且可扩展的干预措施，以预防由伊蚊传播的疾病，如登革热、寨卡病毒和基孔肯雅热。
ClinicalTrials.gov NCT01563640。
