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Fongnikin A, Ahoga J, Ndombidje B, Hueha C, de Souza E, Oti-Tossou R, Govoetchan R, Ngufor C. Mosquito Shield™, a transfluthrin passive emanator, protects against pyrethroid-resistant Anopheles gambiae sensu lato in central Benin. Malar J 2024; 23:225. [PMID: 39085888 PMCID: PMC11292991 DOI: 10.1186/s12936-024-05043-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 07/16/2024] [Indexed: 08/02/2024] Open
Abstract
BACKGROUND Spatial repellents can provide personal and household protection against biting vector mosquitoes by volatizing repellents into the air within a given area. Mosquito Shield™ is a transfluthrin passive emanator undergoing evaluation for malaria control. Studies evaluating its entomological impact against different local malaria vector populations would help guide its deployment in endemic countries. METHODS A two-arm single-blinded small-scale household randomised entomological trial was conducted to assess the impact of Mosquito Shield™ on the human landing rate of wild pyrethroid-resistant Anopheles gambiae sensu lato (s.l.) vector mosquitoes in houses in the Ganhoua village of the Zakpota District of central Benin. From a total of 30 houses, 15 were randomly allocated to receive Mosquito Shield™, while the remainder received a placebo product. The trial lasted through the life of the Mosquito Shield™ product (32 days). Mosquito sampling was performed by human landing catches at baseline and at 6 timepoints post-intervention (days 0-1, 7-8, 14-15, 21-22, 28-29 and 31-32). Collections were performed for 2 nights at each sampling time point. WHO cylinder bioassays were conducted during the trial with F1 An. gambiae s.l. mosquitoes that emerged from larvae from the study area to assess the intensity of resistance to pyrethroids in the wild vector population. RESULTS The vector population in the study area showed a high intensity of resistance to pyrethroids. Baseline An. gambiae s.l. human landing rates were similar in houses in both study arms before product application (11.53/person/night vs 11.67/person/night, p > 0.05). A total of 5736 mosquitoes were collected in the placebo control arm and 3862 in the Mosquito Shield™ arm post-intervention. Overall An. gambiae s.l. post-intervention human landing rates were significantly lower in houses in the Mosquito Shield™ arm (18.13/person/night) compared to the houses in the placebo control arm (26.84/person/night, IRR = 0.658, p < 0.001). Over the lifespan of the product, Mosquito Shield™ provided a significant protective efficacy of 34.2% (22.1-44.4%, p < 0.001) against wild pyrethroid-resistant An. gambiae s.l. vectors compared to the placebo. Human landing rates of other nuisance vector mosquito species (Culex and Mansonia) were also reduced in houses treated with Mosquito Shield™ compared to the placebo. CONCLUSION Mosquito Shield™, a transfluthrin passive emanator, provided significant protection against pyrethroid-resistant malaria vectors to households in Benin. The spatial repellent shows potential to reduce malaria transmission by pyrethroid-resistant An. gambiae s.l. vector mosquitoes and cover gaps in malaria control when deployed to complement existing vector control interventions.
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Affiliation(s)
- Augustin Fongnikin
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Juniace Ahoga
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Boris Ndombidje
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Corneille Hueha
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Esperantos de Souza
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Ruth Oti-Tossou
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Renaud Govoetchan
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
- African Institute for Research in Infectious Diseases (AIRID), Cotonou, Benin
- London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Corine Ngufor
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin.
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin.
- African Institute for Research in Infectious Diseases (AIRID), Cotonou, Benin.
- London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK.
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Gouveia AS, Codeço CT, Ferreira FADS, Cortés JJC, Luz SLB. Diflubenzuron larvicide auto-dissemination: A modeling study. Acta Trop 2024; 258:107325. [PMID: 39032848 DOI: 10.1016/j.actatropica.2024.107325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 06/11/2024] [Accepted: 07/13/2024] [Indexed: 07/23/2024]
Abstract
Proposing substitutes for Pyriproxyfen (PPF) in the auto-dissemination strategy is essential to ensure the continuity of the strategy in the field, especially in the case of the emergence of populations resistant to this larvicide. One possible substitute among the compounds already in use in Brazil is the larvicide Diflubenzuron (DFB). The equation that defines the proportion of oviposition sites (habitats) contaminated by the auto-dissemination strategy was modified to account for the number of visits required to reach the necessary concentration of DFB for contamination, considering scenarios with varying numbers of oviposition sites and mosquito densities. The dissemination was evaluated in oviposition sites of 2 L, 1.5 L, 1 L, 0.5 L, 0.2 L, and 0.1 L. The minimum concentration of active ingredient (a.i) of DFB required for a commercial product to contaminate at least 50% of oviposition sites was also investigated, along with the impact of other vector control methods, such as the removal/destruction of oviposition sites and the use of insecticides to kill adult 'females, on the auto-dissemination approach. The use of pure DFB compounds enabled contamination efficiency of more than 50% in oviposition sites with a volume of less than 2 L in scenarios with fewer oviposition sites. On the other hand, with the use of the commonly used concentration of the product, similar efficacy was only achieved in oviposition sites of 0.1 L and 0.2 L in medium and high infestation scenarios. Strategies that reduce the number of available oviposition sites work synergistically with the auto-dissemination strategy, making it possible to use less concentrated products and contaminated sites of larger volume. The strategy proved to be resilient in situations of insecticide application according to the concentration of DFB used, abundance of females, and low number of oviposition sites. Increasing the number of dissemination traps on the field also contributes to better results, especially for oviposition sites of 0.5 L and 1 L. The results of the model obtained under the stipulated conditions provide further support for the potential use of DFB as a substitute for PPF in the auto-dissemination strategy.
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Affiliation(s)
- Ayrton Sena Gouveia
- Núcleo PReV Amazônia - Instituto Leônidas e Maria Deane - Fiocruz Amazônia; Programa de Computação Científica da Fiocruz - Fundação Oswaldo Cruz, Rio de Janeiro, RJ, Brazil; Programa de Pós-Graduação em Biologia Parasitária, Instituto Oswaldo Cruz, Rio de Janeiro, RJ, Brazil.
| | - Cláudia Torres Codeço
- Programa de Computação Científica da Fiocruz - Fundação Oswaldo Cruz, Rio de Janeiro, RJ, Brazil
| | | | | | - Sergio Luiz Bessa Luz
- Núcleo PReV Amazônia - Instituto Leônidas e Maria Deane - Fiocruz Amazônia; Programa de Pós-Graduação em Biologia Parasitária, Instituto Oswaldo Cruz, Rio de Janeiro, RJ, Brazil
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Montenegro-Quiñonez CA, Louis VR, Horstick O, Velayudhan R, Dambach P, Runge-Ranzinger S. Interventions against Aedes/dengue at the household level: a systematic review and meta-analysis. EBioMedicine 2023; 93:104660. [PMID: 37352828 PMCID: PMC10333437 DOI: 10.1016/j.ebiom.2023.104660] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 05/25/2023] [Accepted: 06/02/2023] [Indexed: 06/25/2023] Open
Abstract
BACKGROUND Because the evidence for the role of structural housing and combinations of interventions (domestic or peri-domestic) against Aedes mosquitoes or dengue is still lacking, this systematic review and meta-analysis aimed to analyse and synthesize research focusing on the household as the unit of allocation. METHODS We searched MEDLINE, LILACS, and Web of Science databases until February 2023 using three general keyword categories: (1) "Aedes" or "dengue"; (2) structural housing interventions including "house", "water", or "drainage"; and (3) vector control interventions of potential relevance and their combinations. We performed a qualitative content analysis and a meta-analysis for 13 entries on dengue seroconversion data. FINDINGS 14,272 articles were screened by titles, 615 by abstracts, 79 by full-text. 61 were selected. Satisfactory data quality allowed for detailed content analysis. Interventions at the household level against the immature mosquito stages (21 studies, 34%) showed positive or mixed results in entomological and epidemiological outcomes (86% and 75% respectively). Combined interventions against immature and adult stages (11 studies, 18%) performed similarly (91% and 67%) while those against the adult mosquitoes (29 studies, 48%) performed less well (79%, 22%). A meta-analysis on seroconversion outcomes showed a not-statistically significant reduction for interventions (log odds-ratio: -0.18 [-0.51, 0.14 95% CI]). INTERPRETATION No basic research on housing structure or modification was eligible for this systematic review but many interventions with clear impact on vector indices and, to a lesser extent, on dengue were described. The small and not-statistically significant effect size of the meta-analysis highlights the difficulty of proving effectiveness against this highly-clustered disease and of overcoming practical implementation obstacles (e.g. efficacy loss, compliance). The long-term success of interventions depends on suitability, community commitment and official support and promotion. The choice of a specific vector control package needs to take all these context-specific aspects into consideration. FUNDING This work was funded by a grant from the World Health Organization (2021/1121668-0, PO 202678425, NTD/VVE).
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Affiliation(s)
- Carlos Alberto Montenegro-Quiñonez
- Heidelberg Institute of Global Health (HIGH), Heidelberg University Hospital, Heidelberg, Germany; Instituto de Investigaciones, Centro Universitario de Zacapa, Universidad de San Carlos de Guatemala, Guatemala.
| | - Valérie R Louis
- Heidelberg Institute of Global Health (HIGH), Heidelberg University Hospital, Heidelberg, Germany.
| | - Olaf Horstick
- Heidelberg Institute of Global Health (HIGH), Heidelberg University Hospital, Heidelberg, Germany.
| | - Raman Velayudhan
- Department of Control of Neglected Tropical Diseases (NTD), World Health Organization, Switzerland.
| | - Peter Dambach
- Heidelberg Institute of Global Health (HIGH), Heidelberg University Hospital, Heidelberg, Germany.
| | - Silvia Runge-Ranzinger
- Heidelberg Institute of Global Health (HIGH), Heidelberg University Hospital, Heidelberg, Germany.
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Bauer IL. The oral repellent - science fiction or common sense? Insects, vector-borne diseases, failing strategies, and a bold proposition. Trop Dis Travel Med Vaccines 2023; 9:7. [PMID: 37381000 DOI: 10.1186/s40794-023-00195-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 06/09/2023] [Indexed: 06/30/2023] Open
Abstract
Over the last decades, unimaginable amounts of money have gone into research and development of vector control measures, repellents, treatment, and vaccines for vector borne diseases. Technological progress and scientific breakthroughs allowed for ever more sophisticated and futuristic strategies. Yet, each year, millions of people still die or suffer from potentially serious consequences of malaria or dengue to more recent infections, such as zika or chikungunya, or of debilitating consequences of neglected tropical diseases. This does not seem value for money. In addition, all current vector control strategies and personal protection methods have shortcomings, some serious, that are either destructive to non-target species or unsatisfactory in their effectiveness. On the other hand, the rapid decline in insect populations and their predators reflects decades-long aggressive and indiscriminate vector control. This major disruption of biodiversity has an impact on human life not anticipated by the well-meaning killing of invertebrates. The objective of this paper is to re-examine current control methods, their effectiveness, their impact on biodiversity, human and animal health, and to call for scientific courage in the pursuit of fresh ideas. This paper brings together topics that are usually presented in isolation, thereby missing important links that offer potential solutions to long-standing problems in global health. First, it serves as a reminder of the importance of insects to human life and discusses the few that play a role in transmitting disease. Next, it examines critically the many currently employed vector control strategies and personal protection methods. Finally, based on new insights into insect chemo-sensation and attractants, this perspective makes a case for revisiting a previously abandoned idea, the oral repellent, and its use via currently successful methods of mass-application. The call is out for focused research to provide a powerful tool for public health, tropical medicine, and travel medicine.
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Affiliation(s)
- Irmgard L Bauer
- College of Healthcare Sciences, Academy - Tropical Health and Medicine, James Cook University, Townsville, QLD, 4811, Australia.
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Silva Martins WF, Reid E, Tomlinson S, Evans G, Gibson J, Guy A, Donnelly M, Weetman D. Improving the efficiency of aerosolized insecticide testing against mosquitoes. Sci Rep 2023; 13:6281. [PMID: 37072522 PMCID: PMC10113189 DOI: 10.1038/s41598-023-33460-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 04/13/2023] [Indexed: 05/03/2023] Open
Abstract
Developing robust and standardised approaches for testing mosquito populations against insecticides is vital for understanding the effectiveness of new active ingredients or formulations. Methods for testing mosquito susceptibility against contact insecticides or products, such as those delivered through public health programmes, are well-established and standardised. Nevertheless, approaches for testing volatile or aerosolized insecticides used in household products can be challenging to implement efficiently. We adapted WHO guidelines for household insecticides to develop a standardised and higher-throughput methodology for testing aerosolized products in a Peet Grady test chamber (PG-chamber) using caged mosquitoes and an efficient decontamination method. The new approach was validated using insecticide resistant and susceptible Aedes and Anopheles mosquito colonies. An added feature is the inclusion of cage-facing cameras to allow real-time quantification of knockdown following insecticide exposure. The wipe-based decontamination method was highly effective for removing pyrethroids' aerosolized oil-based residues from chamber surfaces, with < 2% mortality recorded for susceptible mosquitoes tested directly on the surfaces. There was no spatial heterogeneity for knockdown or mortality of caged mosquitoes within the PG chamber. The dual-cage approach we implement yields eight-times the throughput compared to a free-flight protocol, allows simultaneous testing of different mosquito strains and effectively discriminates susceptible and resistant mosquito colonies tested side-by-side.
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Affiliation(s)
- Walter Fabricio Silva Martins
- Laboratório de Entomologia Médica e Molecular- LEMMol, Universidade Estadual da Paraíba - UEPB, Campina Grande, Brazil.
- Department of Vector Biology, Liverpool School of Tropical Medicine - LSTM, Liverpool, UK.
| | - Emma Reid
- Department of Vector Biology, Liverpool School of Tropical Medicine - LSTM, Liverpool, UK
| | - Sean Tomlinson
- Department of Vector Biology, Liverpool School of Tropical Medicine - LSTM, Liverpool, UK
| | - George Evans
- iiDiagnostics, Liverpool School of Tropical Medicine - LSTM, Liverpool, UK
| | - Jennie Gibson
- iiDiagnostics, Liverpool School of Tropical Medicine - LSTM, Liverpool, UK
| | - Amy Guy
- iiDiagnostics, Liverpool School of Tropical Medicine - LSTM, Liverpool, UK
| | - Martin Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine - LSTM, Liverpool, UK
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine - LSTM, Liverpool, UK
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Seang-Arwut C, Hanboonsong Y, Muenworn V, Rocklöv J, Haque U, Ekalaksananan T, Paul RE, Overgaard HJ. Indoor resting behavior of Aedes aegypti (Diptera: Culicidae) in northeastern Thailand. Parasit Vectors 2023; 16:127. [PMID: 37060087 PMCID: PMC10103527 DOI: 10.1186/s13071-023-05746-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/17/2023] [Indexed: 04/16/2023] Open
Abstract
BACKGROUND Aedes aegypti is a vector of several arboviruses, notably dengue virus (DENV), which causes dengue fever and is often found resting indoors. Culex spp. are largely nuisance mosquitoes but can include species that are vectors of zoonotic pathogens. Vector control is currently the main method to control dengue outbreaks. Indoor residual spraying can be part of an effective vector control strategy but requires an understanding of the resting behavior. Here we focus on the indoor-resting behavior of Ae. aegypti and Culex spp. in northeastern Thailand. METHODS Mosquitoes were collected in 240 houses in rural and urban settings from May to August 2019 at two collection times (morning/afternoon), in four room types (bedroom, bathroom, living room and kitchen) in each house and at three wall heights (< 0.75 m, 0.75-1.5 m, > 1.5 m) using a battery-driven aspirator and sticky traps. Household characteristics were ascertained. Mosquitoes were identified as Ae. aegypti, Aedes albopictus and Culex spp. Dengue virus was detected in Ae. aegypti. Association analyses between urban/rural and within-house location (wall height, room), household variables, geckos and mosquito abundance were performed. RESULTS A total of 2874 mosquitoes were collected using aspirators and 1830 using sticky traps. Aedes aegypti and Culex spp. accounted for 44.78% and 53.17% of the specimens, respectively. Only 2.05% were Ae. albopictus. Aedes aegypti and Culex spp. rested most abundantly at intermediate and low heights in bedrooms or bathrooms (96.6% and 85.2% for each taxon of the total, respectively). Clothes hanging at intermediate heights were associated with higher mean numbers of Ae. aegypti in rural settings (0.81 [SEM: 0.08] vs. low: 0.61 [0.08] and high: 0.32 [0.09]). Use of larval control was associated with lower numbers of Ae. aegypti (yes: 0.61 [0.08]; no: 0.70 [0.07]). All DENV-positive Ae. aegypti (1.7%, 5 of 422) were collected in the rural areas and included specimens with single, double and even triple serotype infections. CONCLUSIONS Knowledge of the indoor resting behavior of adult mosquitoes and associated environmental factors can guide the choice of the most appropriate and effective vector control method. Our work suggests that vector control using targeted indoor residual spraying and/or potentially spatial repellents focusing on walls at heights lower than 1.5 m in bedrooms and bathrooms could be part of an integrated effective strategy for dengue vector control.
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Affiliation(s)
- Chadapond Seang-Arwut
- Department of Entomology, Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand
| | - Yupa Hanboonsong
- Department of Entomology, Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand
| | - Vithee Muenworn
- Department of Entomology, Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand
| | - Joacim Rocklöv
- Heidelberg Institute of Global Health & Heidelberg Interdisciplinary Centre for Scientific Computing, Heidelberg University, Heidelberg, Germany
- Department of Public Health and Clinical Medicine, Section of Sustainable Health, Umeå University, Umea, Sweden
| | - Ubydul Haque
- Rutgers Global Health Institute, New Brunswick, NJ, USA
- Department of Biostatistics and Epidemiology, School of Public Health, Rutgers University, Piscataway, NJ, USA
| | - Tipaya Ekalaksananan
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Richard E Paul
- UMR2000, Ecology and Emergence of Arthropod-Borne Pathogens Unit, Institut Pasteur, Université Paris Cité, CNRS, 75015, Paris, France
| | - Hans J Overgaard
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
- Faculty of Science and Technology, Norwegian University of Life Sciences, Ås, Norway.
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Al-Amin HM, Gyawali N, Graham M, Alam MS, Lenhart A, Hugo LE, Rašić G, Beebe NW, Devine GJ. Insecticide resistance compromises the control of Aedes aegypti in Bangladesh. PEST MANAGEMENT SCIENCE 2023. [PMID: 36942761 DOI: 10.1002/ps.7462] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 02/13/2023] [Accepted: 03/21/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND With no effective drugs or widely available vaccines, dengue control in Bangladesh is dependent on targeting the primary vector Aedes aegypti with insecticides and larval source management. Despite these interventions, the dengue burden is increasing in Bangladesh, and the country experienced its worst outbreak in 2019 with 101 354 hospitalized cases. This may be partially facilitated by the presence of intense insecticide resistance in vector populations. Here, we describe the intensity and mechanisms of resistance to insecticides commonly deployed against Ae. aegypti in Dhaka, Bangladesh. RESULTS Dhaka Ae. aegypti colonies exhibited high-intensity resistance to pyrethroids. Using CDC bottle assays, we recorded 2-24% mortality (recorded at 24 h) to permethrin and 48-94% mortality to deltamethrin, at 10× the diagnostic dose. Bioassays conducted using insecticide-synergist combinations suggested that metabolic mechanisms were contributing to pyrethroid resistance, specifically multi-function oxidases, esterases, and glutathione S-transferases. In addition, kdr alleles were detected, with a high frequency (78-98%) of homozygotes for the V1016G mutation. A large proportion (≤ 74%) of free-flying and resting mosquitoes from Dhaka colonies survived exposure to standard applications of pyrethroid aerosols in an experimental free-flight room. Although that exposure affected the immediate host-seeking behavior of Ae. aegypti, the effect was transient in surviving mosquitoes. CONCLUSION The intense resistance characterized in this study is likely compromising the operational effectiveness of pyrethroids against Ae. aegypti in Dhaka. Switching to alternative chemical classes may offer a medium-term solution, but ultimately a more sustainable and effective approach to controlling dengue vectors is required. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Hasan Mohammad Al-Amin
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
- School of Biological Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Narayan Gyawali
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Melissa Graham
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Mohammad Shafiul Alam
- International Center for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Audrey Lenhart
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Leon E Hugo
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Gordana Rašić
- Mosquito Genomics, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Nigel W Beebe
- School of Biological Sciences, University of Queensland, Brisbane, Queensland, Australia
- CSIRO, Brisbane, Queensland, Australia
| | - Gregor J Devine
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
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Tissera H, Dheerasinghe DSAF, Malavige N, de Silva HA, Morrison AC, Scott TW, Reiner RC, Grieco JP, Achee NL. A cluster-randomized, placebo-controlled trial to evaluate the efficacy of a spatial repellent (Mosquito Shield™) against Aedes-borne virus infection among children ≥ 4-16 years of age in the Gampaha District, Sri Lanka: study protocol (the AEGIS program). Trials 2023; 24:9. [PMID: 36600308 PMCID: PMC9811041 DOI: 10.1186/s13063-022-06998-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 12/08/2022] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Spatial repellents (SRs) have been widely used for prevention of mosquito bites, but their efficacy in reducing Aedes-borne viruses (ABV) has not been tested rigorously at large scale in Asia. To address this knowledge gap, a trial to evaluate the efficacy of Mosquito Shield™, a transfluthrin SR, was developed in Gampaha District of Sri Lanka across three Medical Officer of Health areas; i.e., Negombo, Wattala, and Kelaniya. METHODS This trial is a cluster-randomized, placebo-controlled, double-blinded clinical trial. A total of ~14,430 subjects aged ≥ 6 months in 30 clusters (15 intervention, 15 placebo) from ~3900 households (HH) will be randomly selected for enrolment into a "febrile surveillance cohort." A subset of the surveillance cohort, ~3570 subjects aged ≥4-16 years that test seronegative (naïve) or are serologically positive for a previous single dengue virus (DENV) infection (monotypic) at baseline sampling, will be enrolled into a "longitudinal cohort" for measuring DENV infection based on laboratory-confirmed seroconversion during the trial. Persons identified positive for antibodies against multiple DENV serotypes (multitypic) at baseline will be monitored for secondary analyses. Active ABV disease will be assessed using an enhanced passive surveillance system with case ascertainment performed in designated healthcare facilities. Serum samples will be taken from longitudinal cohort subjects within 1-2 weeks of when intervention is first deployed (T0) with additional samples taken ~12 (T1) and ~24 months (T2) from baseline sampling. DENV seroconversion and ABV active disease rates from baseline (pre-intervention) and follow-up (post-intervention) samples will be compared between intervention and placebo clusters. Participating houses will be monitored entomologically (indoor adult Aedes aegypti population densities and adult female blood fed status) within 3 months before intervention deployment and monthly during the intervention phase. Entomological surveys will monitor indoor adult Ae. aegypti population densities and blood fed status. Dengue incidence in each cohort will be estimated and compared to determine the public health benefit of using an SR. Entomological parameters will be measured to determine if there are entomological correlates of SR efficacy that may be useful for the evaluation of new SR products. DISCUSSION The trial will serve as an efficacy assessment of SR products in South Asia. Results will be submitted to the World Health Organization Vector Control Advisory Group for assessment of public health value towards an endorsement to recommend inclusion of SRs in ABV control programs. TRIAL REGISTRATION Sri Lanka Clinical Trial Registry SLCTR /2022/018. Registered on July 1, 2022. CLINICALTRIALS gov NCT05452447 . Registered on July 11, 2022. The Universal Trial Number is U1111-1275-3055.
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Affiliation(s)
- Hasitha Tissera
- grid.466905.8Epidemiology Unit, Ministry of Health, Colombo, Sri Lanka
| | | | - Neelika Malavige
- grid.267198.30000 0001 1091 4496Department of Immunology and Molecular Medicine, Faculty of Medical Sciences, University of Sri Jayewardenepura, Nugegoda, Sri Lanka
| | - H. Asita de Silva
- grid.45202.310000 0000 8631 5388Clinical Trials Unit, Faculty of Medicine, University of Kelaniya, Kelaniya, Sri Lanka
| | - Amy C. Morrison
- grid.27860.3b0000 0004 1936 9684University of California Davis, Davis, CA USA
| | - Thomas W. Scott
- grid.27860.3b0000 0004 1936 9684University of California Davis, Davis, CA USA
| | - Robert C. Reiner
- grid.34477.330000000122986657University of Washington, Seattle, WA USA
| | - John P. Grieco
- grid.131063.60000 0001 2168 0066Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, 243 Galvin Life Science Center, Notre Dame, IN 46556 USA
| | - Nicole L. Achee
- grid.131063.60000 0001 2168 0066Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, 243 Galvin Life Science Center, Notre Dame, IN 46556 USA
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Abbas MG, Haris A, Binyameen M, Nazir A, Mozūratis R, Azeem M. Chemical Composition, Larvicidal and Repellent Activities of Wild Plant Essential Oils against Aedes aegypti. BIOLOGY 2022; 12:biology12010008. [PMID: 36671701 PMCID: PMC9855110 DOI: 10.3390/biology12010008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/14/2022] [Accepted: 12/17/2022] [Indexed: 12/24/2022]
Abstract
Bio-degradable and eco-friendly essential oils (EOs) extracted from Mentha longifolia, Salsola imbricata, Erigeron bonariensis, E. canadensis, Ailanthus altissima, and Zanthoxylum armatum were investigated for their repellent and larvicidal potential against Aedes aegypti mosquitoes. The EOs of M. longifolia, S. imbricata, E. bonariensis, E. canadensis, A. altissima, and Z. armatum exhibited 99.0%, 96.8%, 40.2%, 41.7%, 29.1%, and 13.2% repellency against mosquitoes at a tested dose of 33.3 μg/cm2, respectively. In time span bioassays, the EOs of M. longifolia, S. imbricata, E. bonariensis, and E. canadensis showed more than 40% repellency for 60 min at a tested dose of 330 μg/cm2. Larvicidal bioassays revealed that larvae of Ae. aegypti were the most susceptible to M. longifolia (LC50, 39.3 mg/L), E. bonariensis (LC50, 26.0 mg/L), E. canadensis (LC50, 35.7 mg/L), and Z. armatum (LC50, 35.9 mg/L) EOs upon 48 h exposure. The most abundant constituents in the EOs of M. longifolia, S. imbricata, E. bonariensis, E. canadensis and A. altissima were piperitone oxide (45.5%), carvone (39.9%), matricaria ester (43.1%), (31.7%) and eugenol (24.4%), respectively. Our study demonstrates that EOs of M. longifolia, S. imbricata, E. bonariensis, and E. canadensis might be used to control Ae. aegypti mosquitoes without harming humans or the environment.
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Affiliation(s)
- Muhammad Ghazanfar Abbas
- Laboratory of Insect Chemical Ecology, Department of Entomology, Faculty of Agricultural Sciences & Technology, Bahauddin Zakariya University, Multan 60800, Pakistan
| | - Abdullah Haris
- Laboratory of Insect Chemical Ecology, Department of Entomology, Faculty of Agricultural Sciences & Technology, Bahauddin Zakariya University, Multan 60800, Pakistan
| | - Muhammad Binyameen
- Laboratory of Insect Chemical Ecology, Department of Entomology, Faculty of Agricultural Sciences & Technology, Bahauddin Zakariya University, Multan 60800, Pakistan
| | - Abdul Nazir
- Department of Environmental Sciences, Abbottabad Campus, COMSATS University Islamabad, Abbottabad 22060, Pakistan
| | - Raimondas Mozūratis
- Department of Zoology, Stockholm University, 10691 Stockholm, Sweden
- Laboratory of Chemical and Behavioural Ecology, Institute of Ecology, Nature Research Centre, LT-08412 Vilnius, Lithuania
- Correspondence: (R.M.); (M.A.); Tel.: +46-73-572-9581 (R.M.)
| | - Muhammad Azeem
- Department of Chemistry, Abbottabad Campus, COMSATS University Islamabad, Abbottabad 22060, Pakistan
- Correspondence: (R.M.); (M.A.); Tel.: +46-73-572-9581 (R.M.)
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10
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Mulderij-Jansen V, Pundir P, Grillet ME, Lakiang T, Gerstenbluth I, Duits A, Tami A, Bailey A. Effectiveness of Aedes-borne infectious disease control in Latin America and the Caribbean region: A scoping review. PLoS One 2022; 17:e0277038. [PMID: 36322603 PMCID: PMC9629598 DOI: 10.1371/journal.pone.0277038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 10/18/2022] [Indexed: 11/05/2022] Open
Abstract
Background Aedes aegypti and Aedes albopictus are primary vectors of emerging or re-emerging arboviruses that threaten public health worldwide. Many efforts have been made to develop interventions to control these Aedes species populations. Still, countries in the Latin America and the Caribbean (LAC) region struggle to create/design/develop sustainable and effective control strategies. This scoping review synthesises evidence concerning the effectiveness of Ae. aegypti and Ae. albopictus prevention and control interventions performed in LAC (2000–2021). The findings can be used to evaluate, compare and develop more effective control strategies. Methodology The review is based on the methodology by Joanna Briggs Institute for conducting a scoping review. The MEDLINE (via PubMed and Web of Science), Cochrane Library, Scopus, EMBASE and ScienceDirect databases were used to search for articles. Grey literature was searched from governmental and non-governmental organisation websites. Four reviewers independently screened all titles and abstracts and full-text of the articles using the Rayyan web application, based on pre-defined eligibility criteria. Results A total of 122 publications were included in the review. Most studies focused on dengue virus infection and data on Ae. aegypti. Entomological data were mainly used to determine the intervention’s effectiveness. An integrated control intervention was the most commonly employed strategy in both regions. Biological control measures, environmental management, and health education campaigns on community participation achieved more sustainable results than an intervention where only a chemical control measure was used. Challenges to implementing interventions were insufficient financial support, resources, workforce, intersectoral collaboration and legislation. Conclusions Based on the synthesised data, an integrated vector (Aedes) management focused on community participation seems to be the most effective approach to mitigate Aedes-borne infectious diseases. Maintaining the approach’s effect remains challenging as it requires multisectoral and multi-disciplinary team engagement and active community participation. Future research needs to address the barriers to program implementation and maintenance as data on this topic is lacking.
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Affiliation(s)
- Vaitiare Mulderij-Jansen
- Department of Medical Microbiology and Infection Prevention, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- Faculty of Geosciences, Department of Human Geography and Spatial Planning, International Development Studies, Utrecht University, Utrecht, Netherlands
- Department of Epidemiology, Curaçao Biomedical & Health Research Institute, Willemstad, Curaçao
- * E-mail:
| | - Prachi Pundir
- George Institute for Global Health, New Delhi, India
| | - Maria E. Grillet
- Facultad de Ciencias, Instituto de Zoología y Ecología Tropical, Universidad Central de Venezuela, Caracas, Venezuela
| | | | - Izzy Gerstenbluth
- Department of Epidemiology, Curaçao Biomedical & Health Research Institute, Willemstad, Curaçao
- Epidemiology and Research Unit, Ministry of Health Environment and Nature of Curaçao, Willemstad, Curaçao
| | - Ashley Duits
- Red Cross Blood Bank Foundation, Willemstad, Curaҫao
- Department of Immunology, Curaçao Biomedical & Health Research Institute, Willemstad, Curaçao
- Institute for Medical Education, University Medical Center Groningen, Groningen, The Netherlands
| | - Adriana Tami
- Department of Medical Microbiology and Infection Prevention, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Ajay Bailey
- Faculty of Geosciences, Department of Human Geography and Spatial Planning, International Development Studies, Utrecht University, Utrecht, Netherlands
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11
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Hugo LE, Rašić G, Maynard AJ, Ambrose L, Liddington C, Thomas CJE, Nath NS, Graham M, Winterford C, Wimalasiri-Yapa BMCR, Xi Z, Beebe NW, Devine GJ. Wolbachia wAlbB inhibit dengue and Zika infection in the mosquito Aedes aegypti with an Australian background. PLoS Negl Trop Dis 2022; 16:e0010786. [PMID: 36227923 PMCID: PMC9562151 DOI: 10.1371/journal.pntd.0010786] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 09/03/2022] [Indexed: 11/18/2022] Open
Abstract
Biological control of mosquito vectors using the endosymbiotic bacteria Wolbachia is an emerging strategy for the management of human arboviral diseases. We recently described the development of a strain of Aedes aegypti infected with the Wolbachia strain wAlbB (referred to as the wAlbB2-F4 strain) through simple backcrossing of wild type Australian mosquitoes with a wAlbB infected Ae. aegypti strain from the USA. Field releases of male wAlbB2-F4 mosquitoes resulted in the successful suppression of wild populations of mosquitoes in the trial sites by exploiting the strain's Wolbachia-induced cytoplasmic incompatibility. We now demonstrate that the strain is resistant to infection by dengue and Zika viruses and is genetically similar to endemic Queensland populations. There was a fourfold reduction in the proportion of wAlbB2-F4 mosquitoes that became infected following a blood meal containing dengue 2 virus (16.7%) compared to wild type mosquitoes (69.2%) and a 6-7 fold reduction in the proportion of wAlbB2-F4 mosquitoes producing virus in saliva following a blood meal containing an epidemic strain of Zika virus (8.7% in comparison to 58.3% in wild type mosquitoes). Restriction-site Associated DNA (RAD) sequencing revealed that wAlbB2-F4 mosquitoes have > 98% Australian ancestry, confirming the successful introduction of the wAlbB2 infection into the Australian genomic background through backcrossing. Genotypic and phenotypic analyses showed the wAlbB2-F4 strain retains the insecticide susceptible phenotype and genotype of native Australian mosquitoes. We demonstrate that the Wolbachia wAlbB2-F4, in addition to being suitable for population suppression programs, can also be effective in population replacement programs given its inhibition of virus infection in mosquitoes. The ease at which a target mosquito population can be transfected with wAlbB2, while retaining the genotypes and phenotypes of the target population, shows the utility of this strain for controlling the Ae. aegypti mosquitoes and the pathogens they transmit.
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Affiliation(s)
- Leon E. Hugo
- QIMR Berghofer, Brisbane, Queensland, Australia
- * E-mail: (LEH); (GJD)
| | | | - Andrew J. Maynard
- School of Biological Sciences, University of Queensland, Brisbane, Australia
| | - Luke Ambrose
- School of Biological Sciences, University of Queensland, Brisbane, Australia
| | | | - Callum J. E. Thomas
- School of Biological Sciences, University of Queensland, Brisbane, Australia
| | | | | | | | | | - Zhiyong Xi
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, United States of America
| | - Nigel W. Beebe
- School of Biological Sciences, University of Queensland, Brisbane, Australia
- CSIRO, Brisbane, Queensland, Australia
| | - Gregor J. Devine
- QIMR Berghofer, Brisbane, Queensland, Australia
- * E-mail: (LEH); (GJD)
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12
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Ahmed M, Nath NS, Hugo LE, Devine GJ, Macdonald J, Pollak NM. Rapid detection of kdr mutation F1534C in Aedes aegypti using recombinase polymerase amplification and lateral flow dipsticks. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2022; 187:105209. [PMID: 36127073 DOI: 10.1016/j.pestbp.2022.105209] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 07/19/2022] [Accepted: 08/08/2022] [Indexed: 06/15/2023]
Abstract
Insecticide resistance monitoring is essential in assessing the efficacy of vector control measures. However, gold standard PCR-based molecular analyses for insecticide resistance detection are often hindered by time-consuming sample processing, as well as considerable infrastructure and resourcing requirements. In this study, we combined a novel one-step sample preparation reagent with a rapid isothermal molecular test that detects a knock down resistance (kdr) mutation (F1534C) that enables pyrethroid resistance in Aedes aegypti mosquitoes. We trialled the rapid F1534C pyrethroid resistance test using insecticide resistant Ae. aegypti mosquito bodies and compared results to a conventional, allele-specific quantitative PCR (AS-qPCR) coupled with melt curve genotyping in corresponding mosquito heads. From a strain of Ae. aegypti established from an insecticide resistant population in Merida, Mexico (n = 27), all the mosquito bodies (n = 27) tested positive with the rapid F1534C test regardless of whether they were homozygous or heterozygous. To assess diagnostic test specificity, we confirmed that F1534 was not detected in laboratory-reared, fully susceptible Ae. aegypti mosquito bodies (n = 28) using the rapid F1534C test or the conventional AS-qPCR melt curve analysis. All corresponding mosquito heads (n = 28) were homozygous wild-type FF1534. The rapid F1534C test thus demonstrated 100% diagnostic sensitivity (95% CI: 87.23% to 100%) and 100% diagnostic specificity (95% CI: 87.66% to 100.00%) for detection of the F1534C pyrethroid resistant single nucleotide polymorphism (SNP) in both heterozygous and homozygous Ae. aegypti. In the collection of mutant mosquitoes from Mexico, CC1534 homozygous mutants occurred at a frequency of 74.1% (n = 20) and FC heterozygous mutants at a frequency of 25.9% (n = 7). The rapid F1534C test significantly reduced the sample processing and testing time from approximately 6 h for the AS-qPCR melt curve analysis to only 25 min. These results demonstrate significant potential for our approach to resistance testing as a field-based, low-resource, rapid alternative to time-consuming and expensive laboratory-based detection.
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Affiliation(s)
- Madeeha Ahmed
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia; School of Science and Engineering, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia.
| | - Nisa Suraj Nath
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, 300 Herston Road, 4006 Herston, QLD, Australia.
| | - Leon E Hugo
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, 300 Herston Road, 4006 Herston, QLD, Australia.
| | - Gregor J Devine
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, 300 Herston Road, 4006 Herston, QLD, Australia.
| | - Joanne Macdonald
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia; School of Science and Engineering, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia.
| | - Nina M Pollak
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia; School of Science and Engineering, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia.
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13
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Kirstein OD, Talavera GA, Wei Z, Ciau-Carrilo KJ, Koyoc-Cardeña E, Puerta-Guardo H, Rodríguez-Martín E, Medina-Barreiro A, Mendoza AC, Piantadosi AL, Manrique-Saide P, Vazquez-Prokopec GM. Natural Aedes-Borne Virus Infection Detected in Male Adult Aedes aegypti (Diptera: Culicidae) Collected From Urban Settings in Mérida, Yucatán, México. JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:1336-1346. [PMID: 35535688 PMCID: PMC9278843 DOI: 10.1093/jme/tjac048] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Indexed: 05/12/2023]
Abstract
Aedes-borne viruses (ABVs) such as dengue (DENV), chikungunya (CHIKV), and Zika (ZIKV) contribute significantly to the global burden of infectious diseases, disproportionately affecting disadvantaged populations from tropical and subtropical urban areas. ABVs can be transmitted from female mosquitoes to their progeny by vertical transmission via transovarial and/or trans-egg vertical transmission and contribute to the maintenance of infected-mosquito populations year-round in endemic regions. This study describes the natural infection rate of DENV, CHIKV, and ZIKV in field-caught male Aedes (Sergentomyia) aegypti (Linnaeus) mosquitoes from Mérida, Yucatán, México, as a proxy for the occurrence of vertical virus transmission. We used indoor sequential sampling with Prokopack aspirators to collect all mosquitoes inside houses from ABV hotspots areas. Collections were performed in a DENV and CHIKV post-epidemic phase and during a period of active ZIKV transmission. We individually RT-qPCR tested all indoor collected Ae. aegypti males (1,278) followed by Sanger sequencing analysis for final confirmation. A total of 6.7% male mosquitoes were positive for ABV (CHIKV = 5.7%; DENV = 0.9%; ZIKV = 0.1%) and came from 21.0% (30/143) houses infested with males. Most ABV-positive male mosquitoes were positive for CHIKV (84.8%). The distribution of ABV-positive Ae. aegypti males was aggregated in a few households, with two houses having 11 ABV-positive males each. We found a positive association between ABV-positive males and females per house. These findings suggested the occurrence of vertical arbovirus transmission within the mosquito populations in an ABV-endemic area and, a mechanism contributing to viral maintenance and virus re-emergence among humans in post-epidemic periods.
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Affiliation(s)
- Oscar D Kirstein
- Department of Environmental Sciences. Emory University, Atlanta, GA, USA
| | - Guadalupe Ayora Talavera
- Laboratorio de Virología, Centro de Investigaciones Regionales “Dr. Hideyo Noguchi”, Universidad Autónoma de Yucatán, Mérida, Yucatán, México
| | - Zhuoran Wei
- Department of Environmental Sciences. Emory University, Atlanta, GA, USA
| | - Karina J Ciau-Carrilo
- Laboratorio de Virología, Centro de Investigaciones Regionales “Dr. Hideyo Noguchi”, Universidad Autónoma de Yucatán, Mérida, Yucatán, México
| | - Edgar Koyoc-Cardeña
- Unidad Colaborativa para Bioensayos Entomológicos, Universidad Autónoma de Yucatán, Mérida, Yucatán, México
| | - Henry Puerta-Guardo
- Laboratorio de Virología, Centro de Investigaciones Regionales “Dr. Hideyo Noguchi”, Universidad Autónoma de Yucatán, Mérida, Yucatán, México
- Unidad Colaborativa para Bioensayos Entomológicos, Universidad Autónoma de Yucatán, Mérida, Yucatán, México
| | - Ester Rodríguez-Martín
- Laboratorio de Virología, Centro de Investigaciones Regionales “Dr. Hideyo Noguchi”, Universidad Autónoma de Yucatán, Mérida, Yucatán, México
| | - Anuar Medina-Barreiro
- Unidad Colaborativa para Bioensayos Entomológicos, Universidad Autónoma de Yucatán, Mérida, Yucatán, México
| | - Azael Che Mendoza
- Unidad Colaborativa para Bioensayos Entomológicos, Universidad Autónoma de Yucatán, Mérida, Yucatán, México
| | - Anne L Piantadosi
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - Pablo Manrique-Saide
- Unidad Colaborativa para Bioensayos Entomológicos, Universidad Autónoma de Yucatán, Mérida, Yucatán, México
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14
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Experimental evaluation of a metofluthrin passive emanator against Aedes albopictus. PLoS One 2022; 17:e0267278. [PMID: 35536780 PMCID: PMC9089854 DOI: 10.1371/journal.pone.0267278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 04/05/2022] [Indexed: 11/19/2022] Open
Abstract
Background With the recent occurrence of locally transmitted Aedes-borne viruses in the continental United States and Europe, and a lack of effective vaccines, new approaches to control Aedes aegypti and Aedes albopictus are needed. In sub-tropical urban settings in the US, Ae. albopictus is a dominant nuisance and arbovirus vector species. Unfortunately, the vector control toolbox against Ae. albopictus is not as well developed as for Ae. aegypti. Here, we evaluate the efficacy, longevity, and range of protectiveness of a novel passive metofluthrin emanator (10% active ingredient in a polyethylene mesh) against Ae. albopictus indoors and outdoors. Methods Four studies were conducted comparing the presence of the metofluthrin emanator to a control lacking emanator with interest in quantifying efficacy by human landing counts. Studies evaluated the effect of an emanator at varying distances from one or more human volunteers indoors and outdoors. Efficacy of emanators over time since activation was also evaluated. Results Mixed-effects models determined that sitting in close proximity to an emanator reduced landings by 89.5% outdoors and by 74.6% indoors. The emanator was determined protective when located immediately next to a human volunteer outdoors but not uniformly protective when located further away. The emanator was protective at all tested distances from the device indoors. Mortality of mosquitoes exposed to metofluthrin emanators was ~2x higher than those who were not exposed in indoor conditions. Finally, a Generalized Additive Model determined that emanators used continuously outdoors lost their effect after 2.5 weeks and stopped inducing paralysis in mosquitoes after 3.8 weeks of use. Conclusions We show strong and lasting efficacy of 10% metofluthrin emanators against field Ae. albopictus both in indoor and outdoor conditions. Metofluthrin emanators can protect people from Ae. albopictus bites, representing a viable option for reducing human-mosquito contacts at home and beyond.
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15
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Ochomo EO, Gimnig JE, Bhattarai A, Samuels AM, Kariuki S, Okello G, Abong'o B, Ouma EA, Kosgei J, Munga S, Njagi K, Odongo W, Liu F, Grieco JP, Achee NL. Evaluation of the protective efficacy of a spatial repellent to reduce malaria incidence in children in western Kenya compared to placebo: study protocol for a cluster-randomized double-blinded control trial (the AEGIS program). Trials 2022; 23:260. [PMID: 35382858 PMCID: PMC8980512 DOI: 10.1186/s13063-022-06196-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 03/24/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Spatial repellents are widely used for prevention of mosquito bites and evidence is building on their public health value, but their efficacy against malaria incidence has never been evaluated in Africa. To address this knowledge gap, a trial to evaluate the efficacy of Mosquito Shield™, a spatial repellent incorporating transfluthrin, was developed for implementation in Busia County, western Kenya where long-lasting insecticidal net coverage is high and baseline malaria transmission is moderate to high year-round. METHODS This trial is designed as a cluster-randomized, placebo-controlled, double-blinded clinical trial. Sixty clusters will be randomly assigned in a 1:1 ratio to receive spatial repellent or placebo. A total of 6120 children aged ≥6 months to 10 years of age will be randomly selected from the study clusters, enrolled into an active cohort (baseline, cohort 1, and cohort 2), and sampled monthly to determine time to first infection by smear microscopy. Each cohort following the implementation of the intervention will be split into two groups, one to estimate direct effect of the spatial repellent and the other to estimate degree of diversion of mosquitoes and malaria transmission to unprotected persons. Malaria incidence in each cohort will be estimated and compared (primary indicator) to determine benefit of using a spatial repellent in a high, year-round malaria transmission setting. Mosquitoes will be collected monthly using CDC light traps to determine if there are entomological correlates of spatial repellent efficacy that may be useful for the evaluation of new spatial repellents. Quarterly human landing catches will assess behavioral effects of the intervention. DISCUSSION Findings will serve as the first cluster-randomized controlled trial powered to detect spatial repellent efficacy to reduce malaria in sub-Saharan Africa where transmission rates are high, insecticide-treated nets are widely deployed, and mosquitoes are resistant to insecticides. Results will be submitted to the World Health Organization Vector Control Advisory Group for assessment of public health value towards an endorsement to recommend inclusion of spatial repellents in malaria control programs. TRIAL REGISTRATION ClinicalTrials.gov NCT04766879 . Registered February 23, 2021.
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Affiliation(s)
- Eric O Ochomo
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - John E Gimnig
- Centers for Disease Control and Prevention, Division of Parasitic Diseases and Malaria, Atlanta, GA, USA
| | - Achuyt Bhattarai
- Centers for Disease Control and Prevention, Division of Parasitic Diseases and Malaria, Atlanta, GA, USA
| | - Aaron M Samuels
- Centers for Disease Control and Prevention, Division of Parasitic Diseases and Malaria, Atlanta, GA, USA
| | - Simon Kariuki
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - George Okello
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Bernard Abong'o
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Eunice A Ouma
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Jackline Kosgei
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Stephen Munga
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Kiambo Njagi
- National Malaria Control Program, Ministry of Health, Kenyatta National Hospital, Nairobi, Kenya
| | - Wycliffe Odongo
- Centers for Disease Control and Prevention, Division of Parasitic Diseases and Malaria, Atlanta, GA, USA
| | - Fang Liu
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, Notre Dame, IN, USA
| | - John P Grieco
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA.
| | - Nicole L Achee
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
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