A cluster-randomized controlled trial to assess the effectiveness of using 15% DEET topical repellent with long-lasting insecticidal nets (LLINs) compared to a placebo lotion on malaria transmission

Abstract Background There is evidence that the Kdr L1014F and Ace-1R G119S mutations involved in pyrethroid and carbamate resistance in Anopheles gambiae influence malaria transmission in sub Saharan Africa. This is likely due to changes in behavior, life history, vectorial competence and capacity. In the present study, performed as part of a two-armed cluster randomized controlled trial (CRT) evaluating the impact of household screening plus a novel insecticide delivery system (In2Care EaveTubes), we investigated the distribution of insecticide target site mutations and their association with the infection status in wild An. gambiae s.l populations. Methods Mosquitoes were captured in 40 villages around Bouaké by human landing catches (HLC), from May 2017 to April 2019. Randomly selected sample of infected and uninfected An.gambiae s.l. with Plasmodium sp. were identified to species and then genotyped for Kdr L1014F and Ace-1R G119S mutations using quantitative polymerase chain reaction (qPCR) assays. The frequencies of the two alleles were compared between An. coluzzii and An. gambiae and then between infected and uninfected groups for each species. Results The presence of An. gambiae (49 %) and An. coluzzii (51%) was confirmed in Bouaké. Both species seemed to transmit equally Plasmodium parasites. Over the study period, the average frequency of the Kdr L1014F and Ace-1R G119S mutations did not vary significantly between study arms. However, the frequency of the Kdr L1014F and Ace-1R G119S resistance alleles were significantly higher in An. gambiae than in An. coluzzii (OR [95%CI]: 59.64 [30.81-131.63] for Kdr and OR [95%CI]: 2.79 [2.17–3.60], for Ace-1R). For both species, there were no significant differences in Kdr L1014F or Ace-1R G119S genotypic and allelic frequency distribution between infected and uninfected specimens (p > 0.05). Conclusions Either alone or in combination, Kdr L1014F and Ace-1R G119S showed no significant association with Plasmodium infection in wild An.gambiae and An. coluzzii, demonstrating similar competence for Plasmodium transmission in Bouaké. Additional factors influencing competence in natural population and those outside allele measurements contributing to resistance should be consider when establishing link between insecticide resistance and vector competence.

Download Full-text

Evaluating the impact of screening plus eave tubes on malaria transmission compared to current best practice in central Côte d’Ivoire: a two armed cluster randomized controlled trial

BMC Public Health ◽

10.1186/s12889-018-5746-5 ◽

2018 ◽

Vol 18 (1) ◽

Cited By ~ 7

Author(s):

Eleanore D. Sternberg ◽

Jackie Cook ◽

Ludovic P. Ahoua Alou ◽

Carine J. Aoura ◽

Serge Brice Assi ◽

...

Keyword(s):

Randomized Controlled Trial ◽

Malaria Transmission ◽

Cote D'ivoire ◽

Best Practice ◽

Côte D’Ivoire ◽

Controlled Trial ◽

Cluster Randomized Controlled Trial ◽

Randomized Controlled ◽

Cluster Randomized ◽

The Impact

Download Full-text

Assessing the efficacy of two dual-active ingredients long-lasting insecticidal nets for the control of malaria transmitted by pyrethroid-resistant vectors in Benin: study protocol for a three-arm, single-blinded, parallel, cluster-randomized controlled trial

BMC Infectious Diseases ◽

10.1186/s12879-021-05879-1 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Manfred Accrombessi ◽

Jackie Cook ◽

Corine Ngufor ◽

Arthur Sovi ◽

Edouard Dangbenon ◽

...

Keyword(s):

Randomized Controlled Trial ◽

Malaria Control ◽

Controlled Trial ◽

Cluster Randomized Controlled Trial ◽

Sub Saharan Africa ◽

Infection Prevalence ◽

Randomized Controlled ◽

Sub Saharan ◽

Cluster Randomized ◽

Long Lasting Insecticidal Nets

Abstract Background Long-lasting insecticidal nets (LLINs) are currently the primary method of malaria control in sub-Saharan Africa and have contributed to a significant reduction in malaria burden over the past 15 years. However, this progress is threatened by the wide-scale selection of insecticide-resistant malaria vectors. It is, therefore, important to accelerate the generation of evidence for new classes of LLINs. Methods This protocol presents a three-arm superiority, single-blinded, cluster randomized controlled trial to evaluate the impact of 2 novel dual-active ingredient LLINs on epidemiological and entomological outcomes in Benin, a malaria-endemic area with highly pyrethroid-resistant vector populations. The study arms consist of (i) Royal Guard® LLIN, a net combining a pyrethroid (alpha-cypermethrin) plus an insect growth regulator (pyriproxyfen), which in the adult female is known to disrupt reproduction and egg fertility; (ii) Interceptor G2® LLIN, a net incorporating two adulticides (alpha-cypermethrin and chlorfenapyr) with different modes of action; and (iii) the control arm, Interceptor® LLIN, a pyrethroid (alpha-cypermethrin) only LLIN. In all arms, one net for every 2 people will be distributed to each household. Sixty clusters were identified and randomised 1:1:1 to each study arm. The primary outcome is malaria case incidence measured over 24 months through active case detection in a cohort of 25 children aged 6 months to 10 years, randomly selected from each cluster. Secondary outcomes include 1) malaria infection prevalence (all ages) and prevalence of moderate to severe anaemia in children under 5 years old, measured at 6 and 18 months post-intervention; 2) entomological indices measured every 3 months using human landing catches over 24 months. Insecticide resistance intensity will also be monitored over the study period. Discussion This study is the second cluster randomised controlled trial to evaluate the efficacy of these next-generation LLINs to control malaria transmitted by insecticide-resistant mosquitoes. The results of this study will form part of the WHO evidence-based review to support potential public health recommendations of these nets and shape malaria control strategies of sub-Saharan Africa for the next decade. Trial registration ClinicalTrials.gov, NCT03931473, registered on 30 April 2019.

Download Full-text