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Ngufor C, Govoetchan R, Fongnikin A, Hueha C, Ahoga J, Syme T, Agbevo A, Daleb A, Small G, Nimmo D, Bradley J, Aikpon R, Iyikirenga L, Osse R, Tokponnon F, Padonou GG. Community evaluation of VECTRON™ T500, a broflanilide insecticide, for indoor residual spraying for malaria vector control in central Benin; a two arm non-inferiority cluster randomised trial. Sci Rep 2023; 13:17852. [PMID: 37857762 PMCID: PMC10587144 DOI: 10.1038/s41598-023-45047-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 10/15/2023] [Indexed: 10/21/2023] Open
Abstract
VECTRON™ T500 is a wettable powder IRS formulation of broflanilide, a newly discovered insecticide. We performed a two-arm non-inferiority community randomised evaluation of VECTRON™ T500, compared to Fludora® Fusion against pyrethroid-resistant Anopheles gambiae s.l. in an area of high coverage with pyrethroid-only nets in the Za-Kpota District of central Benin. One round of IRS was applied in all consenting households in the study area. Sixteen clusters were randomised (1:1) to receive VECTRON™ T500 (100 mg/m2 for broflanilide) or Fludora® Fusion (200 mg/m2 for clothianidin and 25 mg/m2 for deltamethrin). Surveys were performed to assess adverse events and the operational feasibility and acceptability of VECTRON™ T500 among spray operators and household inhabitants. Human landing catches were conducted in 6 households every 1-2 months for up to 18 months post-intervention to assess the impact on vector densities, sporozoite rates and entomological inoculation rates. Bottle bioassays were performed to monitor vector susceptibility to pyrethroids, broflanilide and clothianidin. Monthly wall cone bioassays were conducted for 24 months to assess the residual efficacy of the IRS formulations using susceptible and pyrethroid-resistant An. gambiae s.l. A total of 26,562 female mosquitoes were collected during the study, of which 40% were An. gambiae s.l., the main malaria vector in the study area. The vector population showed high intensity pyrethroid resistance but was susceptible to broflanilide (6 µg/bottle) and clothianidin (90 µg/bottle). Using a non-inferiority margin of 50%, vector density indicated by the human biting rate (bites/person/night) was non-inferior in the VECTRON™ T500 arm compared to the Fludora® Fusion arm both indoors (0.846 bites/p/n in Fludora® Fusion arm vs. 0.741 bites/p/n in VECTRON™ T500 arm, IRR 0.54, 95% CI 0.22-1.35, p = 0.150) and outdoors (0.691 bites/p/n in Fludora® Fusion arm vs. 0.590 bites/p/n in VECTRON™ T500 clusters, IRR 0.75, 95% CI 0.41-1.38, p = 0.297). Sporozoite rates and entomological inoculation rates did not differ significantly between study arms (sporozoite rate: 0.9% vs 1.1%, p = 0. 0.746, EIR: 0.008 vs 0.006 infective bites per person per night, p = 0.589). Cone bioassay mortality with both VECTRON™ T500 and Fludora® Fusion was 100% for 24 months post-IRS application on both cement and mud treated house walls with both susceptible and pyrethroid-resistant strains of An. gambiae s.l. Perceived adverse events reported by spray operators and householders were generally very low (< 6%) in both study arms. VECTRON™ T500 was non-inferior to Fludora® Fusion in reducing the risk of malaria transmission by pyrethroid resistant vectors when applied for IRS in communities in central Benin. The insecticide showed prolonged residual efficacy on house walls, lasting over 24 months and had a high acceptability with homeowners. Community application of VECTRON™ T500 for IRS provides improved and prolonged control of pyrethroid resistant malaria vectors and enhances our capacity to manage insecticide resistance.
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Affiliation(s)
- Corine Ngufor
- London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK.
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin.
- Panafrican Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin.
| | - Renaud Govoetchan
- London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Panafrican Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Augustin Fongnikin
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Panafrican Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Corneille Hueha
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Panafrican Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Juniace Ahoga
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Panafrican Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Thomas Syme
- London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Panafrican Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Abel Agbevo
- London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Panafrican Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Abdoulaye Daleb
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
| | - Graham Small
- Innovative Vector Control Consortium, Liverpool, UK
| | - Derric Nimmo
- Innovative Vector Control Consortium, Liverpool, UK
| | - John Bradley
- London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Rock Aikpon
- National Malaria Control Programme, Ministry of Health, Cotonou, Benin
| | | | - Razaki Osse
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
| | - Filemon Tokponnon
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
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Konkon AK, Padonou GG, Osse R, Salako AS, Zoungbédji DM, Sina H, Sovi A, Tokponnon F, Aïkpon R, Noukpo H, Baba-Moussa L, Akogbéto MC. Insecticide resistance status of Aedes aegypti and Aedes albopictus mosquitoes in southern Benin, West Africa. Trop Med Health 2023; 51:22. [PMID: 37085936 PMCID: PMC10122308 DOI: 10.1186/s41182-023-00514-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 04/09/2023] [Indexed: 04/23/2023] Open
Abstract
BACKGROUND The emergence of insecticide resistance in Aedes mosquitoes could undermine efforts to control arboviruses. The present study aims to assess in some communes of Southern Benin, the susceptibility level of Aedes aegypti (Linnaeus, 1762) and Aedes albopictus (Skuse, 1894) to insecticides commonly used in public health, as well as mechanisms involved. METHODS Females Ae. albopictus and Ae. aegypti collected in Ifangni, Porto-Novo, Avrankou, Adjarra and Kétou from June 2021 to October 2022, were exposed to: deltamethrin 0.05%, permethrin 0.75%, alpha-cypermethrin 0.05%, pirimiphos methyl 0.25% and bendiocarb 0.1%, following the standard WHO susceptibility tube test protocol. In some sites, pre-exposure to the synergist PBO was used to verify if pyrethroid resistance of populations of Aedes was mediated by oxidases. RESULTS Full susceptibility to deltamethrin and permethrin was observed in all tested populations of Ae. albopictus. However, with alphacypermethrin, a suspected resistance was observed in Adjarra (94.67%), Ifangni (93%) and Porto-Novo (94%), and a resistance in Avrankou (83%). The PBO-alphacypermethrin tests performed, led to a full susceptibility (100%) in all four sites, which confirms the full involvement of oxidases in resistance of all tested populations of Ae. albopictus to alphacypermethrin. At the opposite, Aedes aegypti was either resistant or suspected of being resistant to all tested pyrethroids in all four sites, except in Ifangni where a full susceptibility to alphacypermethrin was observed. The full susceptibility of Ae. aegypti to bendiocarb and pirimiphos-methyl in all communes suggests that these two insecticides can be good candidates for an effective control of pyrethroid-resistant Aedes vector populations. Use of permethrin and deltamethrin could also be considered for controlling populations of Ae. albopictus. CONCLUSION Results of the present study will help guide strategy to implement for an effective control of Aedes vector populations in Benin.
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Affiliation(s)
- Alphonse Keller Konkon
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Benin.
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin.
| | - Germain Gil Padonou
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Benin
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Razaki Osse
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Benin
- École de Gestion et d'exploitation des Systèmes d'élevage de l'Université Nationale d'Agriculture de Porto-Novo, Porto-Novo, Benin
| | | | - David Mahouton Zoungbédji
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Benin
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Haziz Sina
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
- Department of Biochemistry and Cellular Biology, Laboratory of Biology and Molecular Typing in Microbiology, University of Abomey-Calavi, Abomey-Calavi, Benin
| | - Arthur Sovi
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Benin
- Faculty of Agronomy, University of Parakou, Parakou, Benin
- Faculty of Infectious and Tropical Diseases, The London School of Hygiene and Tropical Medicine, London, UK
| | - Filemon Tokponnon
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Benin
| | - Rock Aïkpon
- Ministère de la Santé, 08 BP 882, Cotonou, Benin
- Université Nationale des Sciences, Technologies, Ingénierie Et Mathématiques (UNSTIM), Abomey, Benin
| | - Herbert Noukpo
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Benin
| | - Lamine Baba-Moussa
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
- Department of Biochemistry and Cellular Biology, Laboratory of Biology and Molecular Typing in Microbiology, University of Abomey-Calavi, Abomey-Calavi, Benin
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Accrombessi M, Cook J, Ngufor C, Sovi A, Dangbenon E, Yovogan B, Akpovi H, Hounto A, Thickstun C, Padonou GG, Tokponnon F, Messenger LA, Kleinschmidt I, Rowland M, Akogbeto MC, Protopopoff N. 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 Infect Dis 2021; 21:194. [PMID: 33607958 PMCID: PMC7892705 DOI: 10.1186/s12879-021-05879-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 02/09/2021] [Indexed: 11/21/2022] Open
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.
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Affiliation(s)
- Manfred Accrombessi
- Faculty of Infectious and Tropical Diseases, Disease Control Department, London School of Hygiene and Tropical Medicine, WC1E 7HT, London, UK.
| | - Jackie Cook
- Medical Research Council (MRC) International Statistics and Epidemiology Epidemiology Group, London School of Hygiene and Tropical Medicine, WC1E 7HT, London, UK
| | - Corine Ngufor
- Faculty of Infectious and Tropical Diseases, Disease Control Department, London School of Hygiene and Tropical Medicine, WC1E 7HT, London, UK
| | - Arthur Sovi
- Faculty of Infectious and Tropical Diseases, Disease Control Department, London School of Hygiene and Tropical Medicine, WC1E 7HT, London, UK
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Faculty of Agronomy, University of Parakou, Parakou, Benin
| | | | - Boulais Yovogan
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | - Hilaire Akpovi
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | - Aurore Hounto
- National Malaria Control Program, Ministry of Health, Cotonou, Benin
| | - Charles Thickstun
- School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, Ottawa, Canada
| | - Gil G Padonou
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | | | - Louisa A Messenger
- Faculty of Infectious and Tropical Diseases, Disease Control Department, London School of Hygiene and Tropical Medicine, WC1E 7HT, London, UK
| | - Immo Kleinschmidt
- Medical Research Council (MRC) International Statistics and Epidemiology Epidemiology Group, London School of Hygiene and Tropical Medicine, WC1E 7HT, London, UK
- School of Pathology, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
- Southern African Development Community Malaria Elimination Eight Secretariat, Windhoek, Namibia
| | - Mark Rowland
- Faculty of Infectious and Tropical Diseases, Disease Control Department, London School of Hygiene and Tropical Medicine, WC1E 7HT, London, UK
| | | | - Natacha Protopopoff
- Faculty of Infectious and Tropical Diseases, Disease Control Department, London School of Hygiene and Tropical Medicine, WC1E 7HT, London, UK
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