N'Guessan R, Darriet F, Doannio J M, Chandre F, Carnevale P
Institute Pierre Richet, Bouaké, C te d'Ivoire.
Med Vet Entomol. 2001 Mar;15(1):97-104. doi: 10.1046/j.1365-2915.2001.00284.x.
Pyrethroid-impregnated bednets are advocated for personal protection against malaria vectors. To avoid the need for periodic re-treatment, it would be advantageous to have nets that retain insecticidal efficacy for years and withstand repeated washing. Such a type of commercially produced bednet with permethrin 2% incorporated in polyethylene fibres (trademark Olyset Net supplied by Sumika Life-Tech Co., Osaka, Japan) was evaluated against mosquitoes in veranda-trap huts at Yaokoffikro, near Bouaké, C te d'Ivoire, by standard WHOPES phase II procedures. Four Olyset Nets were compared with a standard untreated polyester net as control. They comprised three examples previously used in a village for over 3 years (one washed, one dirty, one very dirty) and a previously unused Olyset Net, newly unwrapped, from the same original batch. Bioassays with 3 min exposure of susceptible Anopheles gambiae Giles (Diptera: Culicidae) gave >99% mortality of female mosquitoes tested on the 'new' Olyset Net. The used Olyset Nets gave mortality rates averaging 83% for the washed net, 85% for the dirty net and 55% for the very dirty net (within 24-h following 3 min exposure). Thus, Olyset Nets were found to remain remarkably effective against susceptible An. gambiae for at least 3 years under field conditions. Wild pyrethroid-resistant populations of Culex quinquefasciatus Say and An. gambiae (savanna cytotype with 96% kdr) were assessed during June-August 1999 for their responses to sleepers protected by nets in the experimental huts. With regard to hut entry by foraging female mosquitoes, Olyset Nets showed some deterrency against An. gambiae (44% reduction by the new net, approximately 20% by the dirty nets, none by the washed net), but not against Cx. quinquefasciatus. Among mosquitoes entering the hut with untreated control net, 30-34% tried to leave (exophily) but were caught in the verandah trap. The permethrin repellency of Olyset Nets increased exophily by 19% for An. gambiae and 14% for Cx. quinquefasciatus. Blood-feeding rates were 16% An. gambiae and 35% Cx. quinquefasciatus in the hut with sleeper under the untreated net (showing considerable prevention of biting), 22-26% of both species in huts with washed or dirty used Olyset Nets (not significantly different from control), while the biting success rate of Cx. quinquefasciatus (but not kdr An. gambiae) was more than halved by the 'new' Olyset Net. Mortality rates of pyrethroid-resistant An. gambiae and Cx. quinquefasciatus from the huts were, respectively, 3% and 8% with the untreated polyester net, 27.5% and 17% with the 'new' Olyset, 15% and 17.5% with the washed Olyset, 16-25% and 17-20% with dirty old Olyset Nets. Kill differences between nets are significantly different for both An. gambiae and Cx. quinquefasciatus. Unfortunately the washed used Olyset Net showed least activity against resistant mosquitoes, despite its greatest activity against susceptible An. gambiae. In each case there was evidence that a high proportion of mosquitoes failed to feed through the net (many of them dying from starvation when they could not leave the closed hut), with indications that dirty Olyset nets enhanced this protective value.
拟除虫菊酯浸渍蚊帐被提倡用于个人防护以抵御疟疾媒介。为避免定期重新处理的需要，拥有能保持数年杀虫效力并经得起反复洗涤的蚊帐将是有利的。通过世界卫生组织疟疾防治规划署（WHOPES）标准的第二阶段程序，在科特迪瓦布阿凯附近的姚科夫克罗的阳台诱捕小屋中，对一种商业生产的、将2%氯菊酯掺入聚乙烯纤维中的蚊帐（商标为Olyset Net，由日本大阪住友生命科技公司供应）进行了蚊虫测试评估。将四张Olyset蚊帐与一张标准的未处理聚酯蚊帐作为对照进行比较。它们包括三个先前在一个村庄使用了三年多的样本（一张洗过的、一张脏的、一张非常脏的）以及一张来自同一原始批次的、新拆开包装的、之前未使用过的Olyset蚊帐。对易感冈比亚按蚊（双翅目：蚊科）进行3分钟暴露的生物测定显示，在“新”的Olyset蚊帐上测试的雌蚊死亡率>99%。使用过的Olyset蚊帐的死亡率平均为：洗过的蚊帐为83%，脏蚊帐为85%，非常脏的蚊帐为55%（在3分钟暴露后的24小时内）。因此，发现Olyset蚊帐在野外条件下对易感冈比亚按蚊至少三年内仍保持显著的有效性。1999年6月至8月期间，对致倦库蚊和冈比亚按蚊（具有96%击倒抗性的稀树草原细胞型）的野外拟除虫菊酯抗性种群进行了评估，以观察它们对实验小屋中使用蚊帐的睡眠者的反应。关于觅食雌蚊进入小屋的情况，Olyset蚊帐对冈比亚按蚊有一定的驱避作用（新蚊帐减少44%，脏蚊帐约减少20%，洗过的蚊帐无驱避作用），但对致倦库蚊没有驱避作用。在通过未处理的对照蚊帐进入小屋的蚊子中，30 - 34%试图离开（外栖性）但被阳台诱捕器捕获。Olyset蚊帐的氯菊酯驱避作用使冈比亚按蚊的外栖性增加了19%，致倦库蚊增加了14%。在未处理蚊帐下有睡眠者的小屋中，冈比亚按蚊的吸血率为16%，致倦库蚊为35%（显示出对叮咬有相当大的预防作用）；在使用过的洗过或脏的Olyset蚊帐的小屋中，两种蚊子的吸血率均为22 - 26%（与对照无显著差异），而“新”的Olyset蚊帐使致倦库蚊（但不包括具有击倒抗性的冈比亚按蚊）的叮咬成功率减半以上。来自小屋的拟除虫菊酯抗性冈比亚按蚊和致倦库蚊的死亡率分别为：未处理的聚酯蚊帐为3%和8%，“新”的Olyset蚊帐为27.5%和17%，洗过的Olyset蚊帐为15%和17.5%，脏的旧Olyset蚊帐为16 - 25%和17 - 20%。两种蚊帐对两种蚊子的杀灭差异均有显著不同。不幸的是，洗过的用过的Olyset蚊帐对抗性蚊子的活性最低，尽管它对易感冈比亚按蚊的活性最高。在每种情况下，都有证据表明很大一部分蚊子未能穿过蚊帐吸血（其中许多在无法离开封闭的小屋时饿死），有迹象表明脏的Olyset蚊帐增强了这种保护作用。
