Anopheles gambiae populations from Burkina Faso show minimal delayed mortality after exposure to insecticide-treated nets
Anopheles gambiae populations from Burkina Faso show minimal delayed mortality after exposure to insecticide-treated nets
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DOI：
10.1186/s13071-019-3872-2
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发表时间：
2020-01-10
影响因子：
3.2
通讯作者：
Ranson, Hilary
中科院分区：
文献类型：
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作者：
Hughes, Angela;Lissenden, Natalie;Ranson, Hilary
背景 长效杀虫蚊帐 (LLIN) 在非洲预防疟疾的功效受到杀虫剂耐药性的威胁。评估 LLIN 暴露后 24 小时死亡率的生物测定已证实，对 LLIN 中使用的拟除虫菊酯浓度的耐药性普遍存在。然而，虽然蚊子可能不再被 LLIN 暴露迅速杀死，但延迟死亡效应已被证明可以降低暴露于蚊帐的蚊子的传播潜力。这被认为可以部分解释 LLIN 对拟除虫菊酯耐药人群的持续功效。布基纳法索是疟疾负担非常高且对拟除虫菊酯具有抗药性媒介的国家之一，但控制这种疾病的进展却停滞不前。我们在该国一个对拟除虫菊酯耐药性很强的地区测量了 LLIN 暴露对蚊子寿命的影响，以确定在此环境下拟除虫菊酯暴露是否仍然会缩短蚊子的寿命。方法 我们使用生存分析和贝叶斯状态空间模型，对来自布基纳法索喀斯喀特地区的冈比亚按蚊种群进行标准实验室 WHO 锥体测试、试管生物测定和实验小屋试验，量化 LLIN 暴露对即时和延迟死亡率的影响。结果 在单次和多次暴露于 PermaNet 2.0 LLIN 后，测试的四个蚊子种群中只有一个显示出延迟死亡的证据。在使用 LLIN 的实验小屋研究中没有发现延迟死亡率。仅当溴氰菊酯浓度增加至标准诊断剂量以上时，世界卫生组织试管生物测定中才观察到延迟死亡率效应。结论 随着蚊子对拟除虫菊酯的抗性强度增加，LLIN 暴露的延迟效应大大减少或消失。鉴于整个非洲疟疾病媒的耐药性迅速增加，确定 LLIN 未能缩短蚊子寿命是否现在是一种普遍现象非常重要，因为这将对这一关键疟疾控制工具的未来产生重要影响。
Background The efficacy of long-lasting insecticidal nets (LLINs) in preventing malaria in Africa is threatened by insecticide resistance. Bioassays assessing 24-hour mortality post-LLIN exposure have established that resistance to the concentration of pyrethroids used in LLINs is widespread. However, although mosquitoes may no longer be rapidly killed by LLIN exposure, a delayed mortality effect has been shown to reduce the transmission potential of mosquitoes exposed to nets. This has been postulated to partially explain the continued efficacy of LLINs against pyrethroid-resistant populations. Burkina Faso is one of a number of countries with very high malaria burdens and pyrethroid-resistant vectors, where progress in controlling this disease has stagnated. We measured the impact of LLIN exposure on mosquito longevity in an area of the country with intense pyrethroid resistance to establish whether pyrethroid exposure was still shortening mosquito lifespan in this setting. Methods We quantified the immediate and delayed mortality effects of LLIN exposure using standard laboratory WHO cone tests, tube bioassays and experimental hut trials on Anopheles gambiae populations originating from the Cascades region of Burkina Faso using survival analysis and a Bayesian state-space model. Results Following single and multiple exposures to a PermaNet 2.0 LLIN only one of the four mosquito populations tested showed evidence of delayed mortality. No delayed mortality was seen in experimental hut studies using LLINs. A delayed mortality effect was only observed in WHO tube bioassays when deltamethrin concentration was increased above the standard diagnostic dose. Conclusions As mosquito pyrethroid-resistance increases in intensity, delayed effects from LLIN exposure are substantially reduced or absent. Given the rapid increase in resistance occurring in malaria vectors across Africa it is important to determine whether the failure of LLINs to shorten mosquito lifespan is now a widespread phenomenon as this will have important implications for the future of this pivotal malaria control tool.