Adding tsetse control to medical activities contributes to decreasing transmission of sleeping sickness in the Mandoul focus (Chad).
Adding tsetse control to medical activities contributes to decreasing transmission of sleeping sickness in the Mandoul focus (Chad).
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DOI：
10.1371/journal.pntd.0005792
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发表时间：
2017-07
影响因子：
3.8
通讯作者：
Solano P
中科院分区：
文献类型：
--
作者：
Mahamat MH;Peka M;Rayaisse JB;Rock KS;Toko MA;Darnas J;Brahim GM;Alkatib AB;Yoni W;Tirados I;Courtin F;Brand SPC;Nersy C;Alfaroukh IO;Torr SJ;Lehane MJ;Solano P
冈比亚昏睡病或 HAT（非洲人类锥虫病）是一种被忽视的热带疾病，由布氏冈比亚锥虫引起，通过河流采采蝇传播。一项全球计划的目标是到 2020 年消除该疾病这一公共卫生问题，到 2030 年停止传播。在乍得南部，Mandoul 地区是冈比亚昏睡病的持续焦点，直到 2013 年，每年仍有约 100 例 HAT 病例得到诊断和治疗。2014 年之前，HAT 的控制仅依靠病例发现和治疗，由于每年对人群进行筛查，导致 HAT 病例数逐渐减少。由于传播和新病例检测的持续存在，我们评估了在病例检测和治疗中添加病媒控制是否可以进一步减少传播，从而降低曼杜尔 HAT 的年发病率。我们特别调查了部署吸引和杀死采采蝇的“小目标”的影响。在采采蝇控制开始之前，对人口进行了普查并绘制了他们的定居点地图。 2013 年 11 月对采采蝇分布和丰度进行了干预前调查，并于 2014 年初、2015 年和 2016 年在采采蝇河流栖息地部署了 2600 个目标。通过 2014 年和 2015 年的 9 次采采蝇监测调查和 4 次人群医学调查评估了对采采蝇和昏睡病发病率的影响。与主动和被动筛查相比，评估采采蝇控制对发病率的相对影响。人口普查显示，Mandoul 焦点附近居住着 38,674 名居民。在 2013 年 11 月的这一重点中，媒介是 Glossina fuscipes fuscipes，从诱捕器中捕获采采蝇的平均数量为 0.7 只苍蝇/诱捕器/天（范围：0-26）。目标部署后，44 个哨兵双锥形诱捕器的采采蝇捕获量有所下降，在 9 次调查中仅捕获了 5 只采采蝇，平均捕获量为 0.005 只采采蝇/诱捕器/天。模型显示，2013 年至 2015 年间报告病例减少的 70.4%（95% CI：51-95%）可归因于病媒控制，其余则归因于医疗干预。同样，微小目标估计可显着减少新感染，由于采采蝇控制，减少了 62.8%（95% CI：59-66%），而增强的被动检测则减少了 8.5%（95% 8-9%）。模型预测预计，如果病媒控制和筛查继续保持目前的水平，那么到 2018 年，该重点区域可实现消除这一公共卫生问题，此外，自 2015 年以来可能几乎没有传播。这项工作表明，微小目标减少了乍得该重点区域采采蝇的数量，这可能中断了传播，而采采蝇控制与医学检测和治疗的结合在减少 2014 年和 2015 年 HAT 发病率方面发挥了重要作用。一项全球计划旨在到 2020 年消除冈比亚昏睡病（非洲人类锥虫病，HAT）这一公共卫生问题。冈比亚 HAT 是一种被忽视的热带疾病，由采采蝇传播的锥虫引起，其控制主要依赖于人类病例的检测和治疗。在乍得南部的 Mandoul 焦点，2002 年至 2013 年间对人口（约 39000 人）进行定期筛查，每年发现和治疗约 100 例病例。我们研究了是否可以通过在医学筛查中添加病媒控制来实现更好的控制。 2014 年 2 月，在采采蝇出没的地区部署了 2600 个经过杀虫剂处理的目标（“小目标”）；采采蝇会被目标吸引，并在接触目标时吸收致命剂量的杀虫剂。使用由 2013 年 11 月至 2016 年 10 月期间定期运行的 44 个诱捕器组成的网络对采采蝇种群进行的监测表明，采采蝇的日均捕获量下降了 99.99%，从部署目标之前的 0.7 只/诱捕器下降到 0.005 只采采蝇/诱捕器。在此期间，主动筛查计划发现的 HAT 病例数量也有所下降。对 2000 年至 2015 年期间报告的 HAT 病例数量的数学模型表明，2014 年至 2015 年期间病例下降的 70% 是由于病媒控制。该模型还表明，这些干预措施的结合可能会阻断传播，并可能导致到 2020 年消除 Mandoul 重点地区的昏睡病。Mandoul 的结果提供了进一步的经验和理论证据，表明冈比亚 HAT 的全球消除可以通过综合使用 (i) 病例检测和治疗以及 (ii) 病媒控制来实现。
Gambian sleeping sickness or HAT (human African trypanosomiasis) is a neglected tropical disease caused by Trypanosoma brucei gambiense transmitted by riverine species of tsetse. A global programme aims to eliminate the disease as a public health problem by 2020 and stop transmission by 2030. In the South of Chad, the Mandoul area is a persistent focus of Gambian sleeping sickness where around 100 HAT cases were still diagnosed and treated annually until 2013. Pre-2014, control of HAT relied solely on case detection and treatment, which lead to a gradual decrease in the number of cases of HAT due to annual screening of the population. Because of the persistence of transmission and detection of new cases, we assessed whether the addition of vector control to case detection and treatment could further reduce transmission and consequently, reduce annual incidence of HAT in Mandoul. In particular, we investigated the impact of deploying ‘tiny targets’ which attract and kill tsetse. Before tsetse control commenced, a census of the human population was conducted and their settlements mapped. A pre-intervention survey of tsetse distribution and abundance was implemented in November 2013 and 2600 targets were deployed in the riverine habitats of tsetse in early 2014, 2015 and 2016. Impact on tsetse and on the incidence of sleeping sickness was assessed through nine tsetse monitoring surveys and four medical surveys of the human population in 2014 and 2015. Mathematical modelling was used to assess the relative impact of tsetse control on incidence compared to active and passive screening. The census indicated that a population of 38674 inhabitants lived in the vicinity of the Mandoul focus. Within this focus in November 2013, the vector is Glossina fuscipes fuscipes and the mean catch of tsetse from traps was 0.7 flies/trap/day (range, 0–26). The catch of tsetse from 44 sentinel biconical traps declined after target deployment with only five tsetse being caught in nine surveys giving a mean catch of 0.005 tsetse/trap/day. Modelling indicates that 70.4% (95% CI: 51–95%) of the reduction in reported cases between 2013 and 2015 can be attributed to vector control with the rest due to medical intervention. Similarly tiny targets are estimated to have reduced new infections dramatically with 62.8% (95% CI: 59–66%) of the reduction due to tsetse control, and 8.5% (95% 8–9%) to enhanced passive detection. Model predictions anticipate that elimination as a public health problem could be achieved by 2018 in this focus if vector control and screening continue at the present level and, furthermore, there may have been virtually no transmission since 2015. This work shows that tiny targets reduced the numbers of tsetse in this focus in Chad, which may have interrupted transmission and the combination of tsetse control to medical detection and treatment has played a major role in reducing in HAT incidence in 2014 and 2015. A global programme aims to eliminate Gambian sleeping sickness (Human African Trypanosomiasis, HAT) as a public health problem by 2020. Gambian HAT is a neglected tropical disease caused by trypanosomes spread by tsetse flies and its control has relied largely on detection and treatment of human cases. In the Mandoul focus of southern Chad, regular screening of the human population (~39000 people) between 2002 and 2013 resulted in the detection and treatment of ~100 cases/year. We examined whether even better control might be achieved through the addition of vector control to medical screening. In February 2014, 2600 insecticide-treated targets (‘Tiny Targets’) were deployed in areas where tsetse were present; tsetse are attracted to the targets and on contacting it they pick up a lethal dose of insecticide. Monitoring of the tsetse population, using a network of 44 traps operated regularly between November 2013 and October 2016, showed that the mean daily catch of tsetse declined by 99.99%, from 0.7 tsetse/trap before targets were deployed to 0.005 tsetse/trap. The number of HAT cases detected by a programme of active screening also declined during this period. Mathematical modelling of the number of HAT cases reported during the period 2000–2015 suggests that 70% of the decline in cases during 2014–2015 was due to vector control. The model also suggests that the combination of these interventions may have interrupted transmission and may to lead to the elimination of sleeping sickness in the Mandoul focus by 2020. The results from Mandoul provide further empirical and theoretical evidence that the global elimination of Gambian HAT can be achieved through the integrated use of (i) case detection and treatment and (ii) vector control.
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