Département Environnement et Santé, Centre Suisse de Recherches Scientifiques, 01 BP 1303 Abidjan 01, Côte d'Ivoire.
Malar J. 2011 Jun 23;10:172. doi: 10.1186/1475-2875-10-172.
Pyrethroid resistance in vectors could limit the efficacy of long-lasting insecticidal nets (LLINs) because all LLINs are currently treated with pyrethroids. The goal of this study was to evaluate the efficacy and wash resistance of PermaNet® 3.0 compared to PermaNet® 2.0 in an area of high pyrethroid in Côte d'Ivoire. PermaNet® 3.0 is impregnated with deltamethrin at 85 mg/m2 on the sides of the net and with deltamethrin and piperonyl butoxide on the roof. PermaNet® 2.0 is impregnated with deltamethrin at 55 mg/m2 across the entire net.
The study was conducted in the station of Yaokoffikro, in central Côte d'Ivoire. The efficacy of intact unwashed and washed LLINs was compared over a 12-week period with a conventionally-treated net (CTN) washed to just before exhaustion. WHO cone bioassays were performed on sub-sections of the nets, using wild-resistant An. gambiae and Kisumu strains. Mosquitoes were collected five days per week and were identified to genus and species level and classified as dead or alive, then unfed or blood-fed.
Mortality rates of over 80% from cone bioassays with wild-caught pyrethroid-resistant An. gambiae s.s were recorded only with unwashed PermaNet® 3.0. Over 12 weeks, a total of 7,291 mosquitoes were collected. There were significantly more An. gambiae s.s. and Culex spp. caught in control huts than with other treatments (P < 0.001). The proportion of mosquitoes exiting the huts was significantly lower with the control than for the treatment arms (P < 0.001). Mortality rates with resistant An. gambiae s.s and Culex spp, were lower for the control than for other treatments (P < 0.001), which did not differ (P > 0.05) except for unwashed PermaNet® 3.0 (P < 0.001), which gave significantly higher mortality (P < 0.001).
This study showed that unwashed PermaNet® 3.0 caused significantly higher mortality against pyrethroid resistant An. gambiae s.s and Culex spp than PermaNet® 2.0 and the CTN. The increased efficacy with unwashed PermaNet® 3.0 over PermaNet® 2.0 and the CTN was also demonstrated by higher KD and mortality rates (KD > 95% and mortality rate > 80%) in cone bioassays performed with wild pyrethroid-resistant An. gambiae s.s from Yaokoffikro.
由于所有长效防虫蚊帐（LLINs）目前均使用拟除虫菊酯处理，因此媒介中的拟除虫菊酯抗药性可能会限制长效防虫蚊帐的效果。本研究的目的是评估在科特迪瓦一个拟除虫菊酯高度耐药的地区，PermaNet® 3.0 与 PermaNet® 2.0 的疗效和耐洗性。PermaNet® 3.0 的网侧浸渍 85 毫克/平方米的氯菊酯，顶篷浸渍氯菊酯和增效醚。PermaNet® 2.0 则在整个蚊帐上浸渍 55 毫克/平方米的氯菊酯。
该研究在科特迪瓦中部的 Yaokoffikro 站进行。在 12 周的时间内，对未清洗和清洗过的 LLIN 与经过清洗至即将失效的常规处理蚊帐（CTN）的疗效进行了比较。在网片的亚区进行了 WHO 锥形生物测定，使用野生抗药性冈比亚按蚊和基苏木株。每周收集 5 天的蚊子，并按属和种进行分类，分为死亡或存活，然后分为未进食或已进食。
只有未清洗的 PermaNet® 3.0 才能记录到来自锥形生物测定的野生捕获的抗拟除虫菊酯冈比亚按蚊 s.s 的死亡率超过 80%。在 12 周的时间里，共收集了 7291 只蚊子。与其他处理方式相比，控制小屋中捕获的冈比亚按蚊 s.s. 和库蚊的数量明显更多（P <0.001）。与处理臂相比，控制小屋中蚊子离开的比例明显更低（P <0.001）。与对照相比，抗性冈比亚按蚊 s.s. 和库蚊的死亡率更低（P <0.001），但除了未清洗的 PermaNet® 3.0（P <0.001）之外，其他处理之间没有差异（P >0.05），未清洗的 PermaNet® 3.0 显著提高了死亡率（P <0.001）。
本研究表明，与 PermaNet® 2.0 和 CTN 相比，未清洗的 PermaNet® 3.0 对耐拟除虫菊酯的冈比亚按蚊 s.s. 和库蚊的死亡率显著更高。在 Yaokoffikro 用野生抗拟除虫菊酯的冈比亚按蚊 s.s.进行的锥形生物测定中，PermaNet® 3.0 的 KD 和死亡率（KD>95%和死亡率>80%）均高于 PermaNet® 2.0 和 CTN，表明未清洗的 PermaNet® 3.0 也具有更高的疗效。
