Combined use of long-lasting insecticidal nets and Bacillus thuringiensis israelensis larviciding, a promising integrated approach against malaria transmission in northern Côte d'Ivoire

• Published in: Malaria Journal
• Main Authors: Jean-Philippe B. Tia, Emile S. F. Tchicaya, Julien Z. B. Zahouli, Allassane F. Ouattara, Laura Vavassori, Jean-Baptiste Assamoi, Graham Small, Benjamin G. Koudou
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2024
• Subjects: Anopheles gambiae; LLIN; Bacillus thuringiensis israelensis; Integrated vector control; Malaria incidence; Côte d’Ivoire; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/s12936-024-04953-8; https://doaj.org/article/048558dd08aa4a21a9142920ba3517b8

Abstract Background 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. Methods 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. Results 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). Conclusions The combined use of LLINs with Bti ...