Malaria Research and Training Center, Faculty of Medicine, Pharmacy and Dentistry, Bamako, BP 1805, Mali.
Acta Trop. 2012 Apr;122(1):1-6. doi: 10.1016/j.actatropica.2011.11.013. Epub 2011 Dec 1.
The rise and spread of Anopheles gambiae s.l. (the major malaria vector sub-Saharan Africa) resistance to pyrethroids is of great concern owing to the predominant role of pyrethroid-treated nets in the WHO global strategy for malaria control. Use of pyrethroids for agricultural purposes may exert a strong selection pressure, favouring the emergence of insecticide resistance. The objective of this study was to evaluate the efficacy of alpha-cypermethrin treated nets in settings where insecticides are used against pests. This was assessed in two ways, i.e. under laboratory conditions using the WHO standard cones test technique and in experimental huts, on Anopheles gambiae s.l. collected in two Malian rural sites, Koumantou characterised by cotton crops and high insecticide use and Sélingué, a rice field area with low insecticide use. According to the WHO standard cones test technique, there was no difference between mosquitoes collected in the two sites; KD50 time was less than 3 min and the KD95 time below 30 min. Nevertheless, in the experimental huts with alpha-cypermethrin treated bed nets, the mosquito mortality rate was significantly lower in Koumantou (102/361, 28.2%) than in Sélingué (122/233, 52.3%) (RR: 0.65, 95%CI: 0.56-0.76) (p<0.001). In addition, in Koumantou the percentage of unfed mosquitoes found in the veranda was much lower in the huts with untreated (26.0%, 33/127) than in those with treated nets (92.2%, 118/128) (p<0.01) while in Sélingué there was no difference between huts with treated and untreated bed nets. Alpha-cypermethrin treated bed nets had a significant effect on mortality and repelling behaviour of Anopheles gambiae s.l. though in Koumantou treated bed nets were less efficacious, possibly due to the intense use of pesticide for agriculture.
冈比亚按蚊（撒哈拉以南非洲主要疟疾传播媒介）对拟除虫菊酯的抗药性不断上升和蔓延，引起了极大关注，因为在世界卫生组织全球疟疾控制战略中，经拟除虫菊酯处理过的蚊帐发挥了主要作用。出于农业用途而使用拟除虫菊酯可能会产生强烈的选择压力，有利于杀虫剂抗性的出现。本研究旨在评估在使用杀虫剂防治害虫的情况下，α-氯氰菊酯处理过的蚊帐的功效。这是通过两种方式进行评估的，即在实验室条件下使用世界卫生组织标准锥形测试技术和在实验棚中进行，实验棚中的蚊子是在马里两个农村地区收集的，Koumantou 以种植棉花和大量使用杀虫剂为特点，而 Sélingué 则是一个水稻种植区，杀虫剂使用量较低。根据世界卫生组织标准锥形测试技术，两个地点收集的蚊子没有差异；KD50 时间不到 3 分钟，KD95 时间低于 30 分钟。然而，在使用 α-氯氰菊酯处理过的床帐的实验棚中，Koumantou 的蚊子死亡率明显低于 Sélingué（Koumantou 为 102/361，28.2%；Sélingué 为 122/233，52.3%）（RR：0.65，95%CI：0.56-0.76）（p<0.001）。此外，在 Koumantou，未进食的蚊子在带未处理帐子的棚屋走廊的比例（26.0%，33/127）远低于带处理过的帐子的棚屋（92.2%，118/128）（p<0.01），而在 Sélingué，带处理过的和未处理过的床帐的棚屋之间没有差异。α-氯氰菊酯处理过的蚊帐对冈比亚按蚊的死亡率和驱避行为有显著影响，尽管在 Koumantou 处理过的蚊帐效果较差，这可能是由于农业上大量使用农药所致。
