坦桑尼亚部署新一代长效双效杀虫剂蚊帐对疟疾媒介抗药性的影响：一项为期 3 年的群组随机对照试验分析。

Effects of next-generation, dual-active-ingredient, long-lasting insecticidal net deployment on insecticide resistance in malaria vectors in Tanzania: an analysis of a 3-year, cluster-randomised controlled trial.

机构信息

Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK; Department of Environmental and Occupational Health, School of Public Health, University of Nevada, Las Vegas, NV, USA; Parasitology and Vector Biology Laboratory, School of Public Health, University of Nevada, Las Vegas, NV, USA.

Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK.

出版信息

Lancet Planet Health. 2023 Aug;7(8):e673-e683. doi: 10.1016/S2542-5196(23)00137-7.

DOI:10.1016/S2542-5196(23)00137-7

PMID:37558348

Abstract

BACKGROUND

Insecticide resistance among malaria-vector species is a pervasive problem that might jeopardise global disease-control efforts. Novel vector-control tools with different modes of action, including long-lasting insecticidal nets (LLINs) incorporating new active ingredients, are urgently needed to delay the evolution and spread of insecticide resistance. We aimed to measure phenotypic and genotypic insecticide-resistance profiles among wild Anopheles collected over 3 years to assess the longitudinal effects of dual-active-ingredient LLINs on insecticide resistance.

METHODS

For this analysis, data nested in a 3-year, four parallel-arm, superiority cluster-randomised controlled trial (cRCT) in Tanzania, collected from 84 clusters (39 307 households) formed of 72 villages in the Misungwi district, were used to measure insecticide-resistance profiles among female Anopheles mosquitoes via insecticide-resistance bioassays and quantitative RT-PCR of metabolic-resistance genes. Wild, blood-fed, indoor-resting mosquitoes were collected annually during the rainy seasons from house walls in clusters from all four trial groups. Mosquitoes were morphologically identified as An gambiae sensu lato (SL) or An funestus SL before separate bioassay testing. The primary outcomes were lethal-dose values for α-cypermethrin, permethrin, and piperonyl butoxide pre-exposure plus permethrin-resistance intensity bioassays, mortality 72 h after insecticidal exposure for chlorfenapyr bioassays, fertility reduction 72 h after insecticidal exposure for pyriproxyfen bioassays, and fold change in metabolic-enzyme expression relative to an insecticide-susceptible laboratory strain. All primary outcomes were measured in An funestus SL 1 year, 2 years, and 3 years after LLIN distribution. Primary outcomes were also assessed in An gambiae SL if enough mosquitoes were collected. The cRCT is registered with ClinicalTrials.gov (NCT03554616).

FINDINGS

Between May 24, 2019, and Oct 25, 2021, 47 224 female Anopheles were collected for resistance monitoring. In the pyrethroid (PY)-LLIN group, there were significant increases in α-cypermethrin-resistance intensity (year 1 LD50=9·52 vs year 2 76·20, p<0·0001) and permethrin-resistance intensity (year 1 13·27 vs year 2 35·83, p=0·0019) in An funestus SL. In the pyriproxyfen PY-LLIN group, there was similar increase in α-cypermethrin-resistance intensity (year 1 0·71 vs year 2 81·56, p<0·0001) and permethrin-resistance intensity (year 1 5·68 vs year 2 50·14, p<0·0001). In the piperonyl butoxide PY-LLIN group, α-cypermethrin-resistance intensity (year 1 33·26 vs year 3 70·22, p=0·0071) and permethrin-resistance intensity (year 1 47·09 vs year 3 2635·29, p<0·0001) also increased over time. In the chlorfenapyr PY-LLIN group, there were no effects on α-cypermethrin-resistance intensity (year 1 0·42 vs year 3 0·99, p=0·54) or permethrin-resistance intensity (data were not estimable due to nearly 100% mortality). There were also minimal reductions in chlorfenapyr susceptibility. However, in the chlorfenapyr PY-LLIN group, a significant decline in piperonyl-butoxide synergy was seen by year 3 (year 1 0·02 vs year 3 0·26, p=0·020). Highly over-expressed detoxification enzymes showed dynamic patterns of selection throughout the trial.

INTERPRETATION

Our phenotypic data supports trial epidemiological findings; chlorfenapyr PY-LLINs provided superior protection from malaria across multiple transmission seasons, with few effects on insecticide-resistance selection. Rapid pyrethroid-resistance intensification in the piperonyl butoxide PY-LLIN group and pre-existing tolerance of pyriproxyfen in vector populations might explain the poorer performance of these two interventions regarding malaria outcomes. Further work is required to elucidate the potential mechanisms driving cross-resistance between pyrethroids and novel active ingredients to better inform the design of pre-emptive resistance-management strategies.

FUNDING

UK Department for International Development; UK Medical Research Council; Wellcome Trust; UK Department of Health and Social Care; UK Foreign, Commonwealth and Development Office; and The Bill and Melinda Gates Foundation via the Innovative Vector Control Consortium.

摘要

背景

疟疾媒介物种的杀虫剂耐药性是一个普遍存在的问题，可能危及全球疾病控制工作。需要具有不同作用模式的新型病媒控制工具，包括纳入新活性成分的长效杀虫蚊帐（LLINs），以延缓杀虫剂耐药性的进化和传播。我们旨在通过对 3 年来收集的野生疟蚊进行表型和基因型杀虫剂耐药性分析，评估双活性成分 LLIN 对杀虫剂耐药性的纵向影响。

方法

本分析使用嵌套于坦桑尼亚的一项为期 3 年、四项平行臂、优势集群随机对照试验（cRCT）的数据，该试验在米松维区的 72 个村庄中的 84 个群组（39307 户家庭）中进行，通过杀虫剂抗药性生物测定和代谢抗性基因的定量 RT-PCR 来测量雌性疟蚊的杀虫剂抗药性谱。在雨季期间，每年从所有四个试验组的群组房屋墙壁上采集吸食血液、室内休息的野生疟蚊。在进行单独的生物测定测试之前，将蚊子进行形态鉴定为冈比亚按蚊复合体（An. gambiae s.l.）或恶性按蚊复合体（An. funestus s.l.）。主要结局是α-氯氰菊酯、氯菊酯和增效醚预暴露加氯菊酯抗药性强度生物测定的致死剂量值、氯氟醚菊酯生物测定后 72 小时的死亡率、吡丙醚生物测定后 72 小时的生殖力降低率以及相对于杀虫剂敏感的实验室品系，代谢酶表达的倍数变化。在 LLIN 分配后的 1 年、2 年和 3 年，测量了所有恶性按蚊 s.l.的主要结局。如果收集到足够的蚊子，也会评估冈比亚按蚊 s.l.的主要结局。该 cRCT 在 ClinicalTrials.gov（NCT03554616）注册。

结果

2019 年 5 月 24 日至 2021 年 10 月 25 日期间，共收集了 47224 只雌性疟蚊进行耐药监测。在拟除虫菊酯（PY）-LLIN 组中，α-氯氰菊酯抗药性强度（第 1 年 LD50=9.52 vs 第 2 年 76.20，p<0.0001）和氯菊酯抗药性强度（第 1 年 13.27 vs 第 2 年 35.83，p=0.0019）显著增加。在吡丙醚 PY-LLIN 组中，α-氯氰菊酯抗药性强度（第 1 年 0.71 vs 第 2 年 81.56，p<0.0001）和氯菊酯抗药性强度（第 1 年 5.68 vs 第 2 年 50.14，p<0.0001）也类似增加。在增效醚 PY-LLIN 组中，α-氯氰菊酯抗药性强度（第 1 年 33.26 vs 第 3 年 70.22，p=0.0071）和氯菊酯抗药性强度（第 1 年 47.09 vs 第 3 年 2635.29，p<0.0001）也随时间增加。在氯氟醚菊酯 PY-LLIN 组中，α-氯氰菊酯抗药性强度（第 1 年 0.42 vs 第 3 年 0.99，p=0.54）或氯菊酯抗药性强度（由于几乎 100%的死亡率，数据不可估计）没有影响。氯氟醚菊酯的敏感性也几乎没有降低。然而，在氯氟醚菊酯 PY-LLIN 组中，增效醚协同作用在第 3 年显著下降（第 1 年 0.02 vs 第 3 年 0.26，p=0.020）。高度过表达的解毒酶显示出整个试验期间的选择动态。

解释

我们的表型数据支持试验的流行病学发现；氯氟醚菊酯 PY-LLINs 在多个传播季节提供了对疟疾的卓越保护，对杀虫剂耐药性选择的影响很小。增效醚 PY-LLIN 组中拟除虫菊酯抗药性强度的快速强化，以及媒介种群中对吡丙醚的预先耐受，可能解释了这两种干预措施在疟疾结果方面的较差表现。需要进一步研究阐明拟除虫菊酯和新型活性成分之间的交叉耐药潜在机制，以为预防性耐药管理策略的设计提供信息。