Université Nangui Abrogoua, Abidjan, Côte d'Ivoire.
Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire.
Malar J. 2024 May 29;23(1):168. doi: 10.1186/s12936-024-04953-8.
The recent reduction in malaria burden in Côte d'Ivoire is largely attributable to the use of long-lasting insecticidal nets (LLINs). However, this progress is threatened by insecticide resistance and behavioral changes in Anopheles gambiae sensu lato (s.l.) populations and residual malaria transmission, and complementary tools are required. Thus, this study aimed to assess the efficacy of the combined use of LLINs and Bacillus thuringiensis israelensis (Bti), in comparison with LLINs.
This study was conducted in the health district of Korhogo, northern Côte d'Ivoire, within two study arms (LLIN + Bti arm and LLIN-only arm) from March 2019 to February 2020. In the LLIN + Bti arm, Anopheles larval habitats were treated every fortnight with Bti in addition to the use of LLINs. Mosquito larvae and adults were sampled and identified morphologically to genus and species using standard methods. The members of the An. gambiae complex were determined using a polymerase chain reaction technique. Plasmodium infection in An. gambiae s.l. and malaria incidence in local people was also assessed.
Overall, Anopheles spp. larval density was lower in the LLIN + Bti arm 0.61 [95% CI 0.41-0.81] larva/dip (l/dip) compared with the LLIN-only arm 3.97 [95% CI 3.56-4.38] l/dip (RR = 6.50; 95% CI 5.81-7.29; P < 0.001). The overall biting rate of An. gambiae s.l. was 0.59 [95% CI 0.43-0.75] biting/person/night in the LLIN + Bti arm against 2.97 [95% CI 2.02-3.93] biting/person/night in LLIN-only arm (P < 0.001). Anopheles gambiae s.l. was predominantly identified as An. gambiae sensu stricto (s.s.) (95.1%, n = 293), followed by Anopheles coluzzii (4.9%; n = 15). The human-blood index was 80.5% (n = 389) in study area. EIR was 1.36 infected bites/person/year (ib/p/y) in the LLIN + Bti arm against 47.71 ib/p/y in the LLIN-only arm. Malaria incidence dramatically declined from 291.8‰ (n = 765) to 111.4‰ (n = 292) in LLIN + Bti arm (P < 0.001).
The combined use of LLINs with Bti significantly reduced the incidence of malaria. The LLINs and Bti duo could be a promising integrated approach for effective vector control of An. gambiae for elimination of malaria.
科特迪瓦疟疾负担的近期减少主要归因于长效驱虫蚊帐（LLINs）的使用。然而，这一进展受到冈比亚按蚊种群的杀虫剂抗性和行为变化以及残留疟疾传播的威胁，需要补充工具。因此，本研究旨在评估 LLINs 和苏云金芽孢杆菌以色列亚种（Bti）联合使用的效果，并与单独使用 LLINs 进行比较。
本研究于 2019 年 3 月至 2020 年 2 月在科特迪瓦北部科霍戈卫生区进行，分为两个研究臂（LLIN+Bti 臂和仅 LLIN 臂）。在 LLIN+Bti 臂中，每隔两周使用 Bti 处理安蚊幼虫栖息地，同时使用 LLINs。使用标准方法对蚊幼虫和成虫进行采样和形态学鉴定，以属和种进行鉴定。使用聚合酶链反应技术确定冈比亚按蚊复合体的成员。还评估了按蚊属的疟原虫感染和当地居民的疟疾发病率。
总体而言，与仅 LLIN 臂相比，LLIN+Bti 臂中的按蚊属幼虫密度更低，为 0.61 [95%置信区间 0.41-0.81] 幼虫/滴（l/dip）（RR=6.50；95%置信区间 5.81-7.29；P<0.001）。LLIN+Bti 臂中冈比亚按蚊 s.l.的总叮咬率为 0.59 [95%置信区间 0.43-0.75] 人/夜，而仅 LLIN 臂中为 2.97 [95%置信区间 2.02-3.93] 人/夜（P<0.001）。冈比亚按蚊 s.l.主要鉴定为冈比亚按蚊敏感型（s.s.）（95.1%，n=293），其次是库蚊（4.9%，n=15）。人群血液指数为 80.5%（n=389）。LLIN+Bti 臂中的 EIR 为 1.36 感染性叮咬/人/年（ib/p/y），而仅 LLIN 臂中的 EIR 为 47.71 ib/p/y。LLIN+Bti 臂中的疟疾发病率从 291.8‰（n=765）急剧下降至 111.4‰（n=292）（P<0.001）。
LLINs 与 Bti 的联合使用显著降低了疟疾的发病率。LLINs 和 Bti 双管齐下可能是一种有前途的综合方法，可有效控制冈比亚按蚊，消除疟疾。
