三年的强化驱虫可以消除土壤传播的蠕虫吗？

The DeWorm3 transmission model seeks to answer the question. The trial is testing the hypothesis that frequent mass drug administration with high coverage can break the transmission of soil-transmitted helminths over a relatively short period of time. A new study aims to forecast the results at the trial endpoint.

詹姆斯·特鲁斯科特（James Truscott）

各种蠕虫卵的拼贴。从左到右：毛刺鸡蛋，带有幼虫孵化的阿斯卡里斯lumbricoides，成年round虫样品，hymenolepis nana，slistosoma mansoni和toxocara canis带有幼虫孵化
SusanA Secretariat, Catalina Maya Rendón, CC BY 2.0 , via Wikimedia Commons

这篇博客文章是系列的一部分，其中包含在LCNTDR收集：NTD控制科学研究的进步,led by theLondon Centre for Neglected Tropical Disease Research(LCNTDR). Stay tuned for updates on Twitter@bugbittentweets和@NTDResearch。You can find other posts in the series这里。

Soil-transmitted helminths(某事)是一群寄生虫感染humans, causing a wide spectrum of disease and morbidity in their hosts, notably anaemia, growth retardation, and delayed cognitive development in children. Approximately1.5 billion peopleare currently thought to be infected with STHs worldwide.

Anthelminthic (deworming) drugs such as albendazole are effective at reducing worm burdens in individuals, but large-scale programs have generally failed to bring about elimination of STH infestation at the population level (check out this previousBugbitten blog了解有关减少STH的全球努力的更多信息）。确实，世界卫生组织目标育龄的儿童和妇女试图控制儿童和妇女的发病率控制（保持感染的患病率和强度较低）break transmission and eliminate。

然而，驱虫3试验（DW3）旨在检验以下假设：频繁（每年两次）大规模药物管理（MDA）具有高覆盖率（> 90％）可以在三年的短期内打破寄生虫的传播。。如果成功，该策略将为大规模发病控制药物管理的当前周期提供明确的终点。DW3是一个基于群集的随机试验这将激烈的6个月MDA与特定国家的护理标准进行了比较，并在印度，贝宁和马拉维的地点进行。该试验的主要目的是通过MDA将STH患病率提高到2％以下，作为消除的指标。

The purpose of我们的研究是在使用在studyto forecast the results at the DW3 trial endpoint and also to predict the longer-term impact of the trial. Baseline data was used to infer parameter values (using aBayesian approach) for a parasite transmission model, independently for each cluster in each country of the study.

拟合的参数代表了个人之间接触的强度和变异性，这些过程最有可能在不同社区和国家之间变化的过程。然后将拟合的参数用于试验的模拟，包括MDA的回合以及对照组和干预组中的护理干预措施以及端点的TRAIL种群的诊断抽样。

拟合过程和模拟的结果强调了集群级别变异性在寄生虫传播中的重要性。如本图所示，参数拟合到基线数据表明群集中种群中种群中种群中寄生虫聚集的广泛范围。

Posterior distributions for negative binomial aggregation parameter, k, and reproduction number, R0, for individual clusters, derived from baseline data at the India site. Bars represent the 95% credible interval for each inferred value. From https://doi.org/10.1186/s13071-020-04572-7

总体而言，预计DW3试验的主要目标是满足的。也就是说，研究臂中的干预组中的患病率降低到不到2％。然而，簇之间的传输强度和寄生虫聚集的变化导致簇之间对6轮MDA的响应范围。下图显示，尽管预计有些簇被清除为寄生虫，但其他簇的影响却较小。影响程度显然与集群中寄生虫的基线流行率无直接相关。

Drop in mean prevalence between the baseline and end point of the trial by cluster. Each vertical line represents the change in prevalence between the baseline and endline of a cluster. Clusters are ordered by baseline prevalence. Panels are stratified by country (rows) and study arm (columns). Diagnostic is Kato-Katz at baseline and endline for consistency. From https://doi.org/10.1186/s13071-020-04572-7

试验结束后，模拟预测未中断传输的聚类将在其寄生虫患病率中经历“反弹”。因此，高覆盖率，高度均匀，MDA的应用可能会导致在处理区域内无寄生虫区域之间寄生虫传播的局部“热点”。

还必须认识到，仿真基础基础的寄生虫传输模型包含尚待测试的假设，鉴于该田地没有适当的数据。一个重要的假设是谁在传播事件中感染谁的细节，这将由行为和社会结构的模式（例如家庭结构）决定。

当DW3数据充分可用时，它们将为模块化者提供有关寄生虫传播性质的宝贵信息，尤其是在较低的患病率下，这将极大地增强模型预测MDA将来影响的能力。

The study featured in this blog post was published in theLCNTDR收集：NTD控制科学研究的进步,led by theLondon Centre for Neglected Tropical Disease Research(LCNTDR). The collection has been出版Parasites & Vectors自2016年以来，并定期发布新文章。该系列的特点是LCNTDR成员机构及其合作者执行的NTD科学研究的最新进展。它的目的是强调LCNTDR为实现联合国可持续发展目标所做的广泛工作，并支持世界卫生组织路线图2021 - 2030年的目标。

LCNTDR始于2013年的公关的目的oviding focused operational and research support for NTDs. LCNTDR, a joint initiative of theNatural History Museum, theLondon School of Hygiene & Tropical Medicine, theRoyal Veterinary College, the儿童发展伙伴关系, theSCI Foundation（以前称为血吸虫病控制计划）和Imperial College London, undertakes interdisciplinary research to build the evidence base around the design, implementation, monitoring and evaluation of NTD programmes.

You can find other blog posts in the series这里。

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