Multi-country assessment of residual bio-efficacy of insecticides used for indoor residual spraying in malaria control on different surface types: results from program monitoring in 17 PMI/USAID-supported IRS countries
Multi-country assessment of residual bio-efficacy of insecticides used for indoor residual spraying in malaria control on different surface types: results from program monitoring in 17 PMI/USAID-supported IRS countries
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DOI：
10.1186/s13071-017-2608-4
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发表时间：
2018-01-30
影响因子：
3.2
通讯作者：
Fornadel, Christen M.
中科院分区：
文献类型：
--
作者：
Dengela, Dereje;Seyoum, Aklilu;Fornadel, Christen M.
背景资料：室内滞留喷洒是指将杀虫剂喷洒在经常成为疟疾病媒蚊子栖息地的家庭建筑物的内墙。如果室内滞留喷洒涉及适当施用所选杀虫剂配方所特有的预定浓度的活性成分，人类接触疟疾病媒的机会就会减少。室内滞留喷洒的影响可能受到杀虫剂剂量、喷洒覆盖率、病媒行为、病媒对杀虫剂的敏感性以及所用杀虫剂的残留效力的影响。本报告汇编了美国总统疟疾倡议/美国国际开发署（美援署）在17个非洲国家开展的室内滞留喷洒运动中使用的杀虫剂的残留药效数据，并将观察到的药效持续时间与世界卫生组织（世卫组织）准则中提议的范围进行了比较。此外，本研究还初步分析了蚊虫死亡率的变化，这取决于喷洒结构的表面材料、国家喷洒计划、实施年份、测试蚊虫的来源和杀虫剂的类型。在贝宁、布基纳法索、埃塞俄比亚、加纳、肯尼亚、利比里亚、马达加斯加、马拉维、马里、莫桑比克、尼日利亚、卢旺达、塞内加尔、坦桑尼亚、乌干达、赞比亚和津巴布韦。世卫组织的锥形生物测定试验被用来评估接触经杀虫剂处理的泥浆、木材、水泥和其他常用住房材料的蚊子的死亡率。在施用IRS后的几周内进行了基线测试，并继续进行后续测试，直到暴露蚊子的死亡率降至80%以下或方案监测期结束。然后根据世卫组织的准则对数月内的残留效力进行了评价，这些准则为建议用于室内滞留喷洒的杀虫剂制剂提供了建议的残留效力范围。在数据允许的情况下，对蚊子死亡率进行直接比较，以确定在比较杀虫剂制剂、国家、年份、表面类型和测试中使用的蚊子来源时是否存在任何显著差异。顺式氯氰菊酯残留药效为4 ~ 10个月（平均= 6.4个月），与WHO指南中提供的疗效范围相比，没有报告表现不佳的事件。溴氰菊酯残留有效性结果报告的范围为1 - 10个月（平均值= 4.9个月），有两例表现不佳。恶虫威的残留药效范围为2周至7个月（平均= 2。8个月），14次未能达到拟定的最低疗效。最后，持久的甲基吡螨酯的疗效范围从2个月至9个月（平均= 5.3个月），但报告13起事件的表现不佳。结论：大部分的数据用于确定应用率和预期的杀虫剂批准用于IRS程序的疗效收集在控制实验室或试点现场研究。然而，在受控条件下获得的结果的普遍性是有限的，不太可能解释当地来源的住房材料，气候和无数其他因素，可能会影响杀虫剂的生物功效的变化。在这里，数据证实了在监测家庭表面喷洒在PMI/USAID支持的IRS运动时观察到的残留效力的变化。除甲型氯氰菊酯外，所有杀虫剂都至少有一次未达到世卫组织标准中提出的最低残留效力范围。然而，这一初步确定全方案杀虫剂生物效力的工作表明，有些杀虫剂，如恶虫威和甲基吡蚜威，可能容易受到当地环境变化的影响。此外，在这项研究中进行的比较分析提供了证据，蚊子死亡率不同的因素，包括：喷洒杀虫剂的类型，表面材料，地理位置，喷洒的年份，和测试的蚊子。因此，必须在当地评估杀虫剂在各种表面上的残留效力，以便为室内滞留喷洒方案的制定提供信息。
Background: Indoor residual spraying (IRS) is the application of insecticide to the interior walls of household structures that often serve as resting sites for mosquito vectors of malaria. Human exposure to malaria vectors is reduced when IRS involves proper application of pre-determined concentrations of the active ingredient specific to the insecticide formulation of choice. The impact of IRS can be affected by the dosage of insecticide, spray coverage, vector behavior, vector susceptibility to insecticides, and the residual efficacy of the insecticide applied. This report compiles data on the residual efficacy of insecticides used in IRS campaigns implemented by the United States President's Malaria Initiative (PMI)/United States Agency for International Development (USAID) in 17 African countries and compares observed length of efficacy to ranges proposed in World Health Organization (WHO) guidelines. Additionally, this study provides initial analysis on variation of mosquito mortality depending on the surface material of sprayed structures, country spray program, year of implementation, source of tested mosquitoes, and type of insecticide.Methods: Residual efficacy of the insecticides used for PMI/USAID-supported IRS campaigns was measured in Benin, Burkina Faso, Ethiopia, Ghana, Kenya, Liberia, Madagascar, Malawi, Mali, Mozambique, Nigeria, Rwanda, Senegal, Tanzania, Uganda, Zambia and Zimbabwe. The WHO cone bioassay tests were used to assess the mortality rate of mosquitoes exposed to insecticide-treated mud, wood, cement, and other commonly used housing materials. Baseline tests were performed within weeks of IRS application and follow-up tests were continued until the mortality of exposed mosquitoes dropped below 80% or the program monitoring period ended. Residual efficacy in months was then evaluated with respect to WHO guidelines that provide suggested ranges of residual efficacy for insecticide formulations recommended for use in IRS. Where the data allowed, direct comparisons of mosquito mortality rates were then made to determine any significant differences when comparing insecticide formulation, country, year, surface type, and the source of the mosquitoes used in testing.Results: The residual efficacy of alpha-cypermethrin ranged from 4 to 10 months (average = 6.4 months), with no reported incidents of underperformance when compared to the efficacy range provided in WHO guidelines. Deltamethrin residual efficacy results reported a range of 1 to 10 months (average = 4.9 months), with two instances of underperformance. The residual efficacy of bendiocarb ranged from 2 weeks to 7 months (average = 2. 8 months) and failed to achieve proposed minimum efficacy on 14 occasions. Lastly, long-lasting pirimiphos-methyl efficacy ranged from 2 months to 9 months (average = 5.3 months), but reported 13 incidents of underperformance.Conclusions: Much of the data used to determine application rate and expected efficacy of insecticides approved for use in IRS programs are collected in controlled laboratory or pilot field studies. However, the generalizability of the results obtained under controlled conditions are limited and unlikely to account for variation in locally sourced housing materials, climate, and the myriad other factors that may influence the bio-efficacy of insecticides. Here, data are presented that confirm the variation in residual efficacy observed when monitoring household surfaces sprayed during PMI/USAID-supported IRS campaigns. All insecticides except alpha-cypermethrin showed evidence of failing to meet the minimum range of residual efficacy proposed in WHO criteria at least once. However, this initial effort in characterizing program-wide insecticide bio-efficacy indicates that some insecticides, such as bendiocarb and pirimiphos-methyl, may be vulnerable to variations in the local environment. Additionally, the comparative analysis performed in this study provides evidence that mosquito mortality rates differ with respect to factors including: the types of insecticide sprayed, surface material, geographical location, year of spraying, and tested mosquitoes. It is, therefore, important to locally assess the residual efficacy of insecticides on various surfaces to inform IRS programming.