Evidence of increasing Leu-Phe knockdown resistance mutation in Anopheles gambiae from Niger following a nationwide long-lasting insecticide-treated nets implementation
Evidence of increasing Leu-Phe knockdown resistance mutation in Anopheles gambiae from Niger following a nationwide long-lasting insecticide-treated nets implementation
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DOI：
10.1186/1475-2875-7-189
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发表时间：
2008-09-25
期刊：
影响因子：
3
通讯作者：
Duchemin, Jean-Bernard
中科院分区：
文献类型：
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作者：
Czeher, Cyrille;Labbo, Rabiou;Duchemin, Jean-Bernard
背景：2005年底，尼日尔全国开展了一项针对最脆弱人群的全国性长效驱虫蚊帐分发活动。在非洲进行的大量研究报告说，存在对各种杀虫剂具有抗性的按蚊种群，部分原因是击倒抗性（kdr）突变，但很少有大规模的操作控制规划与监测这种突变相结合。研究了尼日尔冈比亚按蚊种群中kdr-west (kdr-w) Leu-Phe突变的分布，并在全国实施LLIN后监测了时间变化。方法：2005年、2006年和2007年湿润季节在14个地点采集蚊虫，并在首都尼亚美进行抽样。对冈比亚按蚊标本进行形态鉴定后，利用DNA提取液确定冈比亚按蚊复合体的种类和分子形态，并检测kdr-w突变。结果：对连续三年采集的约1500例标本进行了分析。分析的所有阿拉伯按蚊标本均为纯合易感，而少数冈比亚按蚊S型表现出较高的总体kdr-w频率。M型样品在LLIN分布前总体kdr-w频率较低，在LLIN分布后的两个丰水季样品中kdr-w频率显著增加。在寻找寄主的雌性中，与室内收集的休息雌性相比，反复注意到更高的kdr频率。此外，在尼亚美M型城市人口中的初步结果显示，kdr频率远高于所研究的所有农村地区。讨论：本研究描述了尼日尔冈比亚按蚊种群中首例kdr突变病例。我们怀疑LLIN导致了本研究中观察到的kdr-w突变的重要时间增加。虽然kdr突变仍然处于低水平，但这种快速增长可能会在几年内导致高kdr频率。结论：这些结果对记录蚊媒控制的多重效果，为未来疟疾控制规划制定可持续控制策略具有重要意义。
Background: At the end of 2005, a nationwide long-lasting insecticide-treated net (LLIN) distribution targeting the most vulnerable populations was implemented throughout Niger. A large number of studies in Africa have reported the existence of anopheline populations resistant to various insecticides, partly due to knockdown resistance (kdr) mutations, but few operational wide-scale control programmes were coupled with the monitoring of such mutations. The distribution of the kdr-west (kdr-w) Leu-Phe mutation was studied in Anopheles gambiae s.l. populations from Niger and temporal variations were monitored following the nationwide LLIN implementation.Methods: Mosquitoes were collected from 14 localities during the wet seasons of 2005, 2006 and 2007 with additional sampling in the capital city, Niamey. After morphological identification of Anopheles gambiae s.l. specimens, DNA extracts were used for the determination of species and molecular forms of the Anopheles gambiae complex and for the detection of the kdr-w mutation.Results: Around 1,500 specimens collected in the three consecutive years were analysed. All Anopheles arabiensis specimens analysed were homozygous susceptible, whereas the few Anopheles gambiae S forms exhibited a high overall kdr-w frequency. The M form samples exhibited a low overall kdr-w frequency before the LLIN distribution, that increased significantly in the two wet season collections following the LLIN distribution. Higher kdr frequencies were repeatedly noticed within host-seeking females compared to resting ones in indoor collections. In addition, preliminary results in M form urban populations from Niamey showed far higher kdr frequencies than in all of the rural sites studied.Discussion: This study describes the first case of kdr mutation in Anopheles gambiae populations from Niger. It is suspected that the LLIN have caused the important temporal increase of kdr-w mutation observed during this study. While the kdr mutation is still found at a low level, this rapid increase could potentially lead to high kdr frequencies within a few years.Conclusion: These results are of prime importance in the effort to document multiple effects of operational control programmes on mosquito vectors, and to conceive sustainable control strategies for future malaria control programmes.