Dabiré Roch K, Diabaté Abdoulaye, Baldet Thierry, Paré-Toé Léa, Guiguemdé Robert T, Ouédraogo Jean-Bosco, Skovmand Ole
IRSS, Direction Régionale de Bobo-Dioulasso, BP 545 Bobo-Dioulasso, Burkina Faso, France.
Malar J. 2006 Feb 10;5:12. doi: 10.1186/1475-2875-5-12.
The development of mosquito nets pre-treated with insecticide, Long Lasting Impregnated Nets (LLINs) that last the life span of the net, is a solution to the difficulty of the re-impregnation of conventional nets. Even if they showed a good efficacy in control conditions, their efficacy in the field, particularly in areas with resistance of Anopheles gambiae to pyrethroids, is not well documented. This study compares wide (Olyset) and small (Permanet) mesh LLINs in field conditions, using entomological parameters.
The two LLINs were tested in a rice-growing area of south-western Burkina Faso (West Africa) with year around high density of the main malaria vector An. gambiae s.s. In the study village (VK6), there is a mixed population of two molecular forms of An. gambiae, the S-form which dominates during the rainy season and the M-form which dominates the rest of the year. The two LLINs Olyset and Permanet were distributed in the village and 20 matched houses were selected for comparison with four houses without treated nets.
Mosquito entrance rate was ten fold higher in control houses than in houses with LLINs and there was no difference between the two net types. Among mosquitoes found in the houses, 36 % were dead in LLIN houses compared to 0% in control houses. Blood feeding rate was 80 % in control houses compared to 43 % in LLIN houses. The type of net did not significantly impact any of these parameters. No mosquitoes were found inside Permanet, whereas dead or dying mosquitoes were collected inside the Olyset. More than 60% of mosquitoes found on top or inside the nets had had blood meals from cattle, as shown by ELISA analysis.
The percentage of blood-fed mosquitoes in a bed net study does not necessarily determine net success. The efficacy of the two types of LLINs was comparable, during a period when the S-form of An. gambiae was carrying the kdr gene. Significantly higher numbers of mosquitoes were collected in control houses compared to intervention houses, indicating that the LLINs provided an additional deterrent effect, which enhanced their expected prevention capacity.
经杀虫剂预处理的蚊帐，即长效浸药蚊帐（LLINs），其使用寿命与蚊帐本身相同，这解决了传统蚊帐重新浸药的难题。尽管它们在对照条件下显示出良好的效果，但它们在实地的效果，特别是在冈比亚按蚊对拟除虫菊酯产生抗性的地区，并没有充分的文献记载。本研究使用昆虫学参数，在实地条件下比较了宽网眼（Olyset）和窄网眼（Permanet）的长效浸药蚊帐。
在布基纳法索西南部（西非）的一个水稻种植区对这两种长效浸药蚊帐进行了测试，该地区全年主要疟疾媒介冈比亚按蚊密度都很高。在研究村庄（VK6），存在两种分子形式的冈比亚按蚊混合种群，即S型在雨季占主导，M型在一年中的其他时间占主导。将Olyset和Permanet这两种长效浸药蚊帐分发给村庄，并挑选了20所匹配的房屋与4所未使用处理过蚊帐的房屋进行比较。
对照房屋中的蚊子进入率比使用长效浸药蚊帐的房屋高十倍，且两种蚊帐类型之间没有差异。在房屋中发现的蚊子中，使用长效浸药蚊帐的房屋中有36%的蚊子死亡，而对照房屋中为0%。对照房屋中的吸血率为80%，而使用长效浸药蚊帐的房屋中为43%。蚊帐类型对这些参数均无显著影响。在Permanet蚊帐内未发现蚊子，而在Olyset蚊帐内收集到了死亡或濒死的蚊子。酶联免疫吸附测定分析表明，在蚊帐顶部或内部发现的蚊子中，超过60%以牛为血源。
在蚊帐研究中，吸血蚊子的比例不一定决定蚊帐的成功与否。在冈比亚按蚊S型携带kdr基因的时期，这两种长效浸药蚊帐的效果相当。与干预房屋相比，对照房屋中收集到的蚊子数量显著更多，这表明长效浸药蚊帐提供了额外的驱避效果，增强了其预期的预防能力。
