Environmental Health and Ecological Sciences, Ifakara Health Institute, Ifakara, Tanzania.
Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK.
Malar J. 2023 Feb 4;22(1):43. doi: 10.1186/s12936-023-04476-8.
Early-evening and outdoor-biting mosquitoes may compromise the effectiveness of frontline malaria interventions, notably insecticide-treated nets (ITNs). This study aimed to evaluate the efficacy of low-cost insecticide-treated eave ribbons and sandals as supplementary interventions against indoor-biting and outdoor-biting mosquitoes in south-eastern Tanzania, where ITNs are already widely used.
This study was conducted in three villages, with 72 households participating (24 households per village). The households were divided into four study arms and assigned: transfluthrin-treated sandals (TS), transfluthrin-treated eave ribbons (TER), a combination of TER and TS, or experimental controls. Each arm had 18 households, and all households received new ITNs. Mosquitoes were collected using double net traps (to assess outdoor biting), CDC light traps (to assess indoor biting), and Prokopack aspirators (to assess indoor resting). Protection provided by the interventions was evaluated by comparing mosquito densities between the treatment and control arms. Additional tests were done in experimental huts to assess the mortality of wild mosquitoes exposed to the treatments or controls.
TERs reduced indoor-biting, indoor-resting and outdoor-biting Anopheles arabiensis by 60%, 73% and 41%, respectively, while TS reduced the densities by 18%, 40% and 42%, respectively. When used together, TER & TS reduced indoor-biting, indoor-resting and outdoor-biting An. arabiensis by 53%, 67% and 57%, respectively. Protection against Anopheles funestus ranged from 42 to 69% with TER and from 57 to 74% with TER & TS combined. Mortality of field-collected mosquitoes exposed to TER, TS or both interventions was 56-78% for An. arabiensis and 47-74% for An. funestus.
Transfluthrin-treated eave ribbons and sandals or their combination can offer significant household-level protection against malaria vectors. Their efficacy is magnified by the transfluthrin-induced mortality, which was observed despite the prevailing pyrethroid resistance in the study area. These results suggest that TER and TS could be useful supplementary tools against residual malaria transmission in areas where ITN coverage is high but additional protection is needed against early-evening and outdoor-biting mosquitoes. Further research is needed to validate the performance of these tools in different settings, and assess their long-term effectiveness and feasibility for malaria control.
傍晚和户外叮咬的蚊子可能会降低一线疟疾干预措施的效果，尤其是驱虫蚊帐（ITN）。本研究旨在评估在坦桑尼亚东南部使用广泛的 ITN 之外，低成本的驱虫檐带和凉鞋作为针对室内和户外叮咬蚊子的补充干预措施的效果，该地区有许多傍晚和户外叮咬的蚊子。
这项研究在三个村庄进行，共有 72 户家庭参与（每个村庄 24 户）。家庭被分为四个研究组，并分配：三氟氯氰菊酯处理的凉鞋（TS）、三氟氯氰菊酯处理的檐带（TER）、TER 和 TS 的组合或实验对照。每个组有 18 户家庭，所有家庭都收到了新的 ITN。使用双网捕集器（评估户外叮咬）、CDC 诱蚊灯（评估室内叮咬）和 Prokopack 吸气器（评估室内栖息）收集蚊子。通过比较治疗组和对照组的蚊子密度来评估干预措施提供的保护。在实验小屋中进行了额外的测试，以评估暴露于处理或对照的野生蚊子的死亡率。
TER 分别减少了 60%、73%和 41%的室内叮咬、室内栖息和户外叮咬的阿拉伯按蚊，而 TS 则分别减少了 18%、40%和 42%。当联合使用时，TER & TS 分别减少了 53%、67%和 57%的室内叮咬、室内栖息和户外叮咬的阿拉伯按蚊。TER 对安蚊的保护范围为 42%至 69%，TER 和 TS 联合使用的保护范围为 57%至 74%。暴露于 TER、TS 或两种干预措施的野外采集的蚊子死亡率为 56-78%的阿拉伯按蚊和 47-74%的致倦库蚊。
三氟氯氰菊酯处理的檐带和凉鞋或它们的组合可以为疟疾传播媒介提供显著的家庭层面的保护。TER 诱导的死亡率使它们的效果放大，尽管研究地区普遍存在拟除虫菊酯抗性，但仍观察到这种死亡率。这些结果表明，TER 和 TS 可能是在 ITN 覆盖率高但需要额外保护以抵御傍晚和户外叮咬蚊子的地区对抗残留疟疾传播的有用补充工具。需要进一步研究来验证这些工具在不同环境中的性能，并评估它们长期控制疟疾的效果和可行性。
