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Vajda ÉA, Ross A, Doum D, Fairbanks EL, Chitnis N, Hii J, Moore SJ, Richardson JH, Macdonald M, Sovannaroth S, Kimheng P, McIver DJ, Tatarsky A, Lobo NF. Field evaluation of a volatile pyrethroid spatial repellent and etofenprox treated clothing for outdoor protection against forest malaria vectors in Cambodia. Sci Rep 2024; 14:17348. [PMID: 39069597 PMCID: PMC11284218 DOI: 10.1038/s41598-024-67470-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 07/11/2024] [Indexed: 07/30/2024] Open
Abstract
Cambodia's goal to eliminate malaria by 2025 is challenged by persistent transmission in forest and forest fringe areas, where people are exposed to Anopheles mosquito bites during the day and night. Volatile pyrethroid spatial repellents (VPSRs) and insecticide-treated clothing (ITC) could address these gaps. This study evaluated the outdoor application of one passive transfluthrin-based VPSR, four etofenprox-ITCs paired with a picaridin topical repellent, and a combination of VPSR and ITC against wild Anopheles landing in Cambodia. A 7 × 7 Latin-square study was conducted over 49 collection nights in temporary open structures in Mondulkiri Province. All interventions substantially reduced Anopheles landing, with protective efficacy ranging from 61 to 95%. Mathematical modeling showed significant reductions in vectoral capacity, especially with the combined ITC and VPSR and VPSR alone, albeit with decreased effectiveness over time. These interventions have the potential to reduce outdoor and daytime Anopheles biting, offering valuable contributions to malaria elimination efforts in Cambodia and the Greater Mekong Subregion, contingent upon achieving effective coverage and adherence.
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Affiliation(s)
- Élodie A Vajda
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA.
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland.
- University of Basel, Petersplatz 1, 2003, Basel, Switzerland.
| | - Amanda Ross
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 2003, Basel, Switzerland
| | - Dyna Doum
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
- Health Forefront Organization, Phnom Penh, Cambodia
| | - Emma L Fairbanks
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 2003, Basel, Switzerland
| | - Nakul Chitnis
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 2003, Basel, Switzerland
| | - Jeffrey Hii
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
| | - Sarah J Moore
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 2003, Basel, Switzerland
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 74, Bagamoyo, Tanzania
| | - Jason H Richardson
- Innovative Vector Control Consortium, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, Merseyside, L3 5QA, UK
| | - Michael Macdonald
- Innovative Vector Control Consortium, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, Merseyside, L3 5QA, UK
| | - Siv Sovannaroth
- National Center for Parasitology, Entomology and Malaria Control, 477, Phnom Penh, Cambodia
| | - Pen Kimheng
- Department of Health of Mondulkiri, C5XX+CP4, 76, Krong Saen Monourom, Cambodia
| | - David J McIver
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
| | - Allison Tatarsky
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
| | - Neil F Lobo
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
- University of Notre Dame, Notre Dame, IN, 46556, USA
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Govella NJ, Assenga A, Mlwale AT, Mirzai N, Heffernan E, Moriarty J, Wenger J, Corbel V, McBeath J, Ogoma SB, Killeen GF. Entomological assessment of hessian fabric transfluthrin vapour emanators for protecting against outdoor-biting Aedes aegypti in coastal Tanzania. PLoS One 2024; 19:e0299722. [PMID: 38809841 PMCID: PMC11135681 DOI: 10.1371/journal.pone.0299722] [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: 05/16/2023] [Accepted: 02/13/2024] [Indexed: 05/31/2024] Open
Abstract
BACKGROUND A low technology emanator device for slowly releasing vapour of the volatile pyrethroid transfluthrin was recently developed in Tanzania that provides robust protection against night biting Anopheles and Culex vectors of malaria and filariasis for several months. Here these same emanator devices were assessed in Dar es Salaam city, as a means of protection against outdoor-biting Aedes (Stegomia) aegypti, the most important vector of human arboviruses worldwide, in parallel with similar studies in Haiti and Brazil. METHODS A series of entomological experiments were conducted under field and semi-field conditions, to evaluate whether transfluthrin emanators protect against wild Ae. aegypti, and also compare the transfluthrin responsiveness of Ae. aegypti originating from wild-caught eggs to established pyrethroid-susceptible Ae. aegypti and Anopheles gambiae colonies. Preliminary measurements of transfluthrin vapour concentration in air samples collected near treated emanators were conducted by gas chromatography-mass spectrometry. RESULTS Two full field experiments with four different emanator designs and three different transfluthrin formulations consistently indicated negligible reduction of human landing rates by wild Ae. aegypti. Under semi-field conditions in large cages, 50 to 60% reductions of landing rates were observed, regardless of which transfluthrin dose, capture method, emanator placement position, or source of mosquitoes (mildly pyrethroid resistant wild caught Ae. aegypti or pyrethroid-susceptible colonies of Ae. aegypti and An. gambiae) was used. Air samples collected immediately downwind from an emanator treated with the highest transfluthrin dose (15g), contained 12 to 19 μg/m3 transfluthrin vapour. CONCLUSIONS It appears unlikely that the moderate levels of pyrethroid resistance observed in wild Ae. aegypti can explain the modest-to-undetectable levels of protection exhibited. While potential inhalation exposure could be of concern for the highest (15g) dose evaluated, 3g of transfluthrin appears sufficient to achieve the modest levels of protection that were demonstrated entomologically. While the generally low levels of protection against Aedes reported here from Tanzania, and from similar entomological studies in Haiti and Brazil, are discouraging, complementary social science studies in Haiti and Brazil suggest end-users perceive valuable levels of protection against mosquitoes. It therefore remains unclear whether transfluthrin emanators have potential for protecting against Aedes vectors of important human arboviruses.
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Affiliation(s)
- Nicodem J. Govella
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
- African Institution of Science and Technology, School of Life Science and Bio-Engineering, The Nelson Mandela, Tengeru, Arusha, United Republic of Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Alphonce Assenga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Amos T. Mlwale
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Nosrat Mirzai
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Eimear Heffernan
- Centre for Research into Atmospheric Chemistry, School of Chemistry, University College Cork, Cork, Republic of Ireland
- Environmental Research Institute, University College Cork, Cork, Republic of Ireland
| | - Jennie Moriarty
- Centre for Research into Atmospheric Chemistry, School of Chemistry, University College Cork, Cork, Republic of Ireland
- Environmental Research Institute, University College Cork, Cork, Republic of Ireland
| | - John Wenger
- Centre for Research into Atmospheric Chemistry, School of Chemistry, University College Cork, Cork, Republic of Ireland
- Environmental Research Institute, University College Cork, Cork, Republic of Ireland
| | - Vincent Corbel
- Institut de Recherche pour le Developpement, University of Montpellier, Montpellier, France
- Laboratório de Fisiologia e Controle de Artrópodes Vetores (Laficave), Instituto Oswaldo Cruz (IOC), Fundação Oswaldo Cruz (FIOCRUZ), Avenida Brasil, Rio de Janeiro-RJ, Brazil
| | - Justin McBeath
- Envu UK Ltd, Cambridge, Milton, Cambridge, United Kingdom
| | | | - Gerry F. Killeen
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
- Environmental Research Institute, University College Cork, Cork, Republic of Ireland
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
- School of Biological Earth & Environmental Sciences, Environmental Research Institute, University College Cork, Cork, Republic of Ireland
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Supreme C, Damus O, Frederick J, Lemoine JF, Raccurt C, McBeath J, Mirzai N, Ogoma SB, Corbel V, Impoinvil D, Killeen GF, Czeher C. Entomological assessment of hessian fabric transfluthrin vapour emanators as a means to protect against outdoor-biting Aedes after providing them to households for routine use in Port-au-Prince, Haiti. PLoS One 2024; 19:e0298919. [PMID: 38805442 PMCID: PMC11132518 DOI: 10.1371/journal.pone.0298919] [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: 05/16/2023] [Accepted: 01/31/2024] [Indexed: 05/30/2024] Open
Abstract
BACKGROUND A simple treated fabric device for passively emanating the volatile pyrethroid transfluthrin was recently developed in Tanzania that protected against nocturnal Anopheles and Culex mosquitoes for several months. Here these transfluthrin emanators were assessed in Port-au-Prince, Haiti against outdoor-biting Aedes. METHODS Transfluthrin emanators were distributed to participating households in poor-to-middle class urban neighbourhoods and evaluated once every two months in terms of their effects on human landing rates of wild Aedes populations. A series of three such entomological assessment experiments were conducted, to examine the influence of changing weather conditions, various transfluthrin formulations and emanator placement on protective efficacy measurements. Laboratory experiments assessed resistance of local Aedes aegypti to transfluthrin and deltamethrin, and the irritancy and repellency of the transfluthrin-treated fabric used in the field. RESULTS Across all three entomological field assessments, little evidence of protection against wild Ae. aegypti was observed, regardless of weather conditions, transfluthrin formulation or emanator placement: A generalized linear mixed model fitted to the pooled data from all three assessment rounds (921 females caught over 5129 hours) estimated a relative landing rate [95% Confidence interval] of 0.87 [0.73, 1.04] for users of treated versus untreated emanators (P = 0.1241). Wild Ae. aegypti in this setting were clearly resistant to transfluthrin when compared to a fully susceptible colony. CONCLUSIONS Transfluthrin emanators had little if any apparent effect upon Aedes landing rates by wild Ae. aegypti in urban Haiti, and similar results have been obtained by comparable studies in Tanzania, Brazil and Peru. In stark contrast, however, parallel sociological assessments of perspectives among these same end-users in urban Haitian communities indicate strong satisfaction in terms of perceived protection against mosquitoes. It remains unclear why the results obtained from these complementary entomological and sociological assessments in Haiti differ so much, as do those from a similar set of studies in Brazil. It is encouraging, however, that similar contrasts between the entomological and epidemiological results of a recent large-scale assessment of another transfluthrin emanator product in Peru, which indicate they provide useful protection against Aedes-borne arboviral infections, despite apparently providing only modest protection against Aedes mosquito bites.
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Affiliation(s)
| | | | - Joseph Frederick
- Programme National de Contrôle de la Malaria, Ministère de la Santé Publique et de la Population, Port-au-Prince, Republic of Haiti
| | - Jean-Frantz Lemoine
- Programme National de Contrôle de la Malaria, Ministère de la Santé Publique et de la Population, Port-au-Prince, Republic of Haiti
| | | | - Justin McBeath
- Envu UK Ltd, Cambridge, Milton, Cambridge, United Kingdom
| | - Nosrat Mirzai
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | | | - Vincent Corbel
- Institut de Recherche pour le Developpement, University of Montpellier, Montpellier, France
- Laboratório de Fisiologia e Controle de Artrópodes Vetores (Laficave), Instituto Oswaldo Cruz (IOC), Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, RJ, Brazil
| | - Daniel Impoinvil
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Gerry F. Killeen
- Ifakara Health Institute, Ifakara, Morogoro, United Republic of Tanzania
- Liverpool School of Tropical Medicine, Department of Vector Biology, Liverpool, United Kingdom
- School of Biological Earth & Environmental Sciences, Environmental Research Institute, University College Cork, Cork, Republic of Ireland
| | - Cyrille Czeher
- Institut de Recherche pour le Developpement, University of Montpellier, Montpellier, France
- Entente Interdépartementale pour la Démoustication du Littoral Méditerranéen (EID Méditerranée), Montpellier, France
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Ahebwa A, Hii J, Neoh KB, Leepasert T, Chareonviriyaphap T. Effects of transfluthrin-treated jute and cotton clothing against resistant and susceptible Aedes aegypti (Diptera: Culicidae) in a semifield system. JOURNAL OF MEDICAL ENTOMOLOGY 2024; 61:181-190. [PMID: 37936536 DOI: 10.1093/jme/tjad145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 09/18/2023] [Accepted: 10/25/2023] [Indexed: 11/09/2023]
Abstract
Volatile pyrethroids exert a range of both lethal and behavioral effects on mosquitoes through the passive release of insecticides into the atmosphere. We investigated the protective efficacy (PE) of transfluthrin-treated jute (TI-jute) and cotton (TI-cotton) fabrics, worn at the back of a protective black vest, against laboratory-reared pyrethroid susceptible and resistant strains of Aedes aegypti (L.) in a semifield system (SFS). Each fabric (1,029 cm2) was treated with 1.79 mg/cm2 of transfluthrin as the intervention. Human landing collections were conducted by 2 collectors seated in designated treatment and control compartments of the SFS. The trials were conducted for 41 days, with 16 days partitioned into morning and evening phases. Furthermore, we examined blood feeding behavior and fecundity of the surviving mosquitoes post-exposure. Results showed that in the morning, the PE of TI-jute (49.4%) was higher than that of TI-cotton (36.8%). TI-jute demonstrated a lower PE of 9.6% against the transfluthrin-resistant strain. Remarkably, a significantly higher number of eggs were laid by the transfluthrin-resistant mosquitoes that survived the intervention (36.5 eggs/female) compared to the control group (11.8 eggs/female). These findings suggest that TI-jute can help protect against bites and alter the life traits of Ae. aegypti. The study highlights that the timing of the intervention during the day affected the efficacy of TI-jute and TI-cotton, while sublethal exposure to transfluthrin stimulated egg production in the resistant strain. These are critical challenges that warrant attention in vector control strategies. Investigating this phenomenon in mosquito reproduction necessitates future research at a molecular level.
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Affiliation(s)
- Alex Ahebwa
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand
| | - Jeffrey Hii
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand
- College of Public Health, Medical and Veterinary Sciences, James Cook University, North Queensland, QLD 4810, Australia
| | - Kok-Boon Neoh
- Department of Entomology, National Chung Hsing University, Taichung, Taiwan
| | - Theerachart Leepasert
- Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Theeraphap Chareonviriyaphap
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand
- Royal Society of Thailand, Bangkok 10900, Thailand
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Bayer BE, Aldridge RL, Moreno BJ, Golden FV, Gibson S, Wahl JL, Linthicum KJ. Transfluthrin diffusers do not protect two-person US military tents from mosquitoes in open field and canopy warm-temperate habitats. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2023; 5:100156. [PMID: 38187816 PMCID: PMC10770594 DOI: 10.1016/j.crpvbd.2023.100156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 11/02/2023] [Accepted: 11/20/2023] [Indexed: 01/09/2024]
Abstract
Spatial repellents are volatile or volatilized chemicals that may repel arthropod vectors in free space, preventing bites and reducing the potential for pathogen transmission. In a 21-week field study, we investigated the efficacy of passive transfluthrin-impregnated diffusers placed in two-person United States (US) military tents located in canopy and open field habitats in north Florida to prevent mosquitoes from entering. Mosquito collections with US Centers for Disease Control and Prevention traps baited with light and carbon dioxide were conducted weekly for weeks 0-4, every two weeks for weeks 5-10, and monthly for weeks 11-21. Our results demonstrated that these transfluthrin-impregnated devices did not function as spatial repellents as expected and did not create a mosquito-free zone of protection. Instead, we observed consistently higher collections of mosquitoes from tents with transfluthrin-impregnated diffusers, and higher rates of mosquito mortality in collections from tents with transfluthrin diffusers, compared to untreated control tents. Based on these findings we do not recommend the use of passive transfluthrin-impregnated diffusers for mosquito protection in two-person US military tents in warm-temperate environments similar to north Florida.
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Affiliation(s)
- Barbara E. Bayer
- United States Department of Agriculture, Agricultural Research Service, Center for Medical, Agricultural, and Veterinary Entomology, 1600 SW 23rd Drive, Gainesville, FL, 32608, USA
| | - Robert L. Aldridge
- United States Department of Agriculture, Agricultural Research Service, Center for Medical, Agricultural, and Veterinary Entomology, 1600 SW 23rd Drive, Gainesville, FL, 32608, USA
| | - Bianca J. Moreno
- United States Department of Agriculture, Agricultural Research Service, Center for Medical, Agricultural, and Veterinary Entomology, 1600 SW 23rd Drive, Gainesville, FL, 32608, USA
| | - Frances V. Golden
- United States Department of Agriculture, Agricultural Research Service, Center for Medical, Agricultural, and Veterinary Entomology, 1600 SW 23rd Drive, Gainesville, FL, 32608, USA
| | - Seth Gibson
- United States Department of Agriculture, Agricultural Research Service, Center for Medical, Agricultural, and Veterinary Entomology, 1600 SW 23rd Drive, Gainesville, FL, 32608, USA
| | - Jeffrey L. Wahl
- Camp Blanding Joint Training Center, Environmental Safety and Health, Starke, FL, 32091, USA
| | - Kenneth J. Linthicum
- United States Department of Agriculture, Agricultural Research Service, Center for Medical, Agricultural, and Veterinary Entomology, 1600 SW 23rd Drive, Gainesville, FL, 32608, USA
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Ridha MR, Marlinae L, Zubaidah T, Fadillah NA, Widjaja J, Rosadi D, Rahayu N, Ningsih M, Desimal I, Sofyandi A. Control methods for invasive mosquitoes of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) in Indonesia. Vet World 2023; 16:1952-1963. [PMID: 37859959 PMCID: PMC10583872 DOI: 10.14202/vetworld.2023.1952-1963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 08/30/2023] [Indexed: 10/21/2023] Open
Abstract
The two invasive mosquito species in Indonesia are Aedes aegypti and Ae. albopictus. These mosquitoes are a serious nuisance to humans and are also the primary vectors of several foreign pathogens, such as dengue, Zika, and chikungunya viruses. Efforts must be made to reduce the possibility of mosquito bites and the potential for disease transmission. Given the invasion of these two Aedes species, this approach should be considered as part of an integrated strategy to manage them. This review discusses existing and developing control techniques for invasive Ae. aegypti and Ae. albopictus, with an emphasis on those that have been and are being used in Indonesia. Environmental, mechanical, biological (e.g., Bacillus thuringiensis and Wolbachia), and chemical (e.g., insect growth regulators and pyrethroids) approaches are discussed in this review, considering their effectiveness, sustainability, and control methods.
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Affiliation(s)
- Muhammad Rasyid Ridha
- Vector-borne and Zoonotic Diseases Research Group, Research Center for Public Health and Nutrition, Cibinong Science Center, National Research and Innovation Agency, Jl. Raya Jakarta-Bogor KM.46, Bogor, West Java, 16915, Indonesia
| | - Lenie Marlinae
- Department of Environmental Health, Public Health Study Program, Medical Faculty, Universitas Labung Mangkurat, Jl. A. Yani, Km. 36 Banjarbaru, South Kalimantan, Indonesia
| | - Tien Zubaidah
- Environmental Health Program, Banjarmasin Health Polytechnic, Jl. H. Mistar Cokrokusumo No.1A, Kemuning, Banjar Baru, South Kalimantan, 70714, Indonesia
| | - Noor Ahda Fadillah
- Department of Epidemiology, Public Health Study Program, Medical Faculty, Universitas Labung Mangkurat, Jl. A. Yani, Km. 36 Banjarbaru, South Kalimantan, Indonesia
| | - Junus Widjaja
- Vector-borne and Zoonotic Diseases Research Group, Research Center for Public Health and Nutrition, Cibinong Science Center, National Research and Innovation Agency, Jl. Raya Jakarta-Bogor KM.46, Bogor, West Java, 16915, Indonesia
| | - Dian Rosadi
- Department of Epidemiology, Public Health Study Program, Medical Faculty, Universitas Labung Mangkurat, Jl. A. Yani, Km. 36 Banjarbaru, South Kalimantan, Indonesia
| | - Nita Rahayu
- Vector-borne and Zoonotic Diseases Research Group, Research Center for Public Health and Nutrition, Cibinong Science Center, National Research and Innovation Agency, Jl. Raya Jakarta-Bogor KM.46, Bogor, West Java, 16915, Indonesia
| | - Murtiana Ningsih
- Public Health Study Program, Sports Sciences and Public Health Faculty, Universitas Pendidikan Mataram, Jl. Pemuda No. 59 A Mataram West Nusa Tenggara, Indonesia
| | - Iwan Desimal
- Public Health Study Program, Sports Sciences and Public Health Faculty, Universitas Pendidikan Mataram, Jl. Pemuda No. 59 A Mataram West Nusa Tenggara, Indonesia
| | - Arif Sofyandi
- Public Health Study Program, Sports Sciences and Public Health Faculty, Universitas Pendidikan Mataram, Jl. Pemuda No. 59 A Mataram West Nusa Tenggara, Indonesia
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Fillinger U, Denz A, Njoroge MM, Tambwe MM, Takken W, van Loon JJA, Moore SJ, Saddler A, Chitnis N, Hiscox A. A randomized, double-blind placebo-control study assessing the protective efficacy of an odour-based 'push-pull' malaria vector control strategy in reducing human-vector contact. Sci Rep 2023; 13:11197. [PMID: 37433881 DOI: 10.1038/s41598-023-38463-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 07/08/2023] [Indexed: 07/13/2023] Open
Abstract
Novel malaria vector control strategies targeting the odour-orientation of mosquitoes during host-seeking, such as 'attract-and-kill' or 'push-and-pull', have been suggested as complementary tools to indoor residual spraying and long-lasting insecticidal nets. These would be particularly beneficial if they can target vectors in the peri-domestic space where people are unprotected by traditional interventions. A randomized double-blind placebo-control study was implemented in western Kenya to evaluate: a 'push' intervention (spatial repellent) using transfluthrin-treated fabric strips positioned at open eave gaps of houses; a 'pull' intervention placing an odour-baited mosquito trap at a 5 m distance from a house; the combined 'push-pull' package; and the control where houses contained all elements but without active ingredients. Treatments were rotated through 12 houses in a randomized-block design. Outdoor biting was estimated using human landing catches, and indoor mosquito densities using light-traps. None of the interventions provided any protection from outdoor biting malaria vectors. The 'push' reduced indoor vector densities dominated by Anopheles funestus by around two thirds. The 'pull' device did not add any benefit. In the light of the high Anopheles arabiensis biting densities outdoors in the study location, the search for efficient outdoor protection and effective pull components needs to continue.
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Affiliation(s)
- Ulrike Fillinger
- International Centre of Insect Physiology and Ecology (Icipe), Human Health Theme, Nairobi, 00100, Kenya.
| | - Adrian Denz
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, Switzerland
- University of Basel, Petersplatz 1, Basel, Switzerland
| | - Margaret M Njoroge
- International Centre of Insect Physiology and Ecology (Icipe), Human Health Theme, Nairobi, 00100, Kenya
- Laboratory of Entomology, Wageningen University & Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Mohamed M Tambwe
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, Switzerland
- University of Basel, Petersplatz 1, Basel, Switzerland
- Vector Control Product Testing Unit (VCPTU), Department of Environmental Health and Ecological Sciences, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Joop J A van Loon
- Laboratory of Entomology, Wageningen University & Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Sarah J Moore
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, Switzerland
- University of Basel, Petersplatz 1, Basel, Switzerland
- Vector Control Product Testing Unit (VCPTU), Department of Environmental Health and Ecological Sciences, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- The Nelson Mandela African Institution of Science and Technology (NM-AIST), Tengeru, P.O. Box 447, Arusha, Tanzania
| | - Adam Saddler
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, Switzerland
- University of Basel, Petersplatz 1, Basel, Switzerland
- Vector Control Product Testing Unit (VCPTU), Department of Environmental Health and Ecological Sciences, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- Telethon Kids Institute, Perth, Australia
| | - Nakul Chitnis
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, Switzerland
- University of Basel, Petersplatz 1, Basel, Switzerland
| | - Alexandra Hiscox
- Laboratory of Entomology, Wageningen University & Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
- Arctech Innovation Ltd., The Cube, Londoneast-Uk Business and Technical Park, Yew Tree Avenue, Dagenham, RM10 7FN, UK
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Vajda ÉA, Saeung M, Ross A, McIver DJ, Tatarsky A, Moore SJ, Lobo NF, Chareonviriyaphap T. A semi-field evaluation in Thailand of the use of human landing catches (HLC) versus human-baited double net trap (HDN) for assessing the impact of a volatile pyrethroid spatial repellent and pyrethroid-treated clothing on Anopheles minimus landing. Malar J 2023; 22:202. [PMID: 37400831 PMCID: PMC10318828 DOI: 10.1186/s12936-023-04619-x] [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: 02/27/2023] [Accepted: 06/10/2023] [Indexed: 07/05/2023] Open
Abstract
BACKGROUND The mosquito landing rate measured by human landing catches (HLC) is the conventional endpoint used to evaluate the impact of vector control interventions on human-vector exposure. Non-exposure based alternatives to the HLC are desirable to minimize the risk of accidental mosquito bites. One such alternative is the human-baited double net trap (HDN), but the estimated personal protection of interventions using the HDN has not been compared to the efficacy estimated using HLC. This semi-field study in Sai Yok District, Kanchanaburi Province, Thailand, evaluates the performance of the HLC and the HDN for estimating the effect on Anopheles minimus landing rates of two intervention types characterized by contrasting modes of action, a volatile pyrethroid spatial repellent (VSPR) and insecticide-treated clothing (ITC). METHODS Two experiments to evaluate the protective efficacy of (1) a VPSR and (2) ITC, were performed. A block randomized cross-over design over 32 nights was carried out with both the HLC or HDN. Eight replicates per combination of collection method and intervention or control arm were conducted. For each replicate, 100 An. minimus were released and were collected for 6 h. The odds ratio (OR) of the released An. minimus mosquitoes landing in the intervention compared to the control arm was estimated using logistic regression, including collection method, treatment, and experimental day as fixed effects. RESULTS For the VPSR, the protective efficacy was similar for the two methods: 99.3%, 95% CI (99.5-99.0) when measured by HLC, and 100% (100, Inf) when measured by HDN where no mosquitoes were caught (interaction test p = 0.99). For the ITC, the protective efficacy was 70% (60-77%) measured by HLC but there was no evidence of protection when measured by HDN [4% increase (15-27%)] (interaction test p < 0.001). CONCLUSIONS Interactions between mosquitoes, bite prevention tools and the sampling method may impact the estimated intervention protective efficacy. Consequently, the sampling method must be considered when evaluating these interventions. The HDN is a valid alternative trapping method (relative to the HLC) for evaluating the impact of bite prevention methods that affect mosquito behaviour at a distance (e.g. VPSR), but not for interventions that operate through tarsal contact (e.g., ITC).
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Affiliation(s)
- Élodie A Vajda
- Malaria Elimination Initiative, University of California, 550 16th street, San Francisco, CA, 94158, USA.
- Swiss Tropical and Public Health Institute (Swiss TPH), Kreuzstrasse 2, 4123, Allschwil, Switzerland.
- University of Basel, Petersplatz 1, CH-2003, Basel, Switzerland.
| | - Manop Saeung
- Kasetsart University, 50 Thanon Ngamwongwan, Lat Yao, Chatuchak, Bangkok, 10900, Thailand
| | - Amanda Ross
- Swiss Tropical and Public Health Institute (Swiss TPH), Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, CH-2003, Basel, Switzerland
| | - David J McIver
- Malaria Elimination Initiative, University of California, 550 16th street, San Francisco, CA, 94158, USA
| | - Allison Tatarsky
- Malaria Elimination Initiative, University of California, 550 16th street, San Francisco, CA, 94158, USA
| | - Sarah J Moore
- Swiss Tropical and Public Health Institute (Swiss TPH), Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, CH-2003, Basel, Switzerland
- Vector Control Product Testing Unit, Department of Environmental and Ecological Sciences, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- Nelson Mandela African Institute of Science and Technology (NM-AIST), P.O. Box 447, Tengeru, Tanzania
| | - Neil F Lobo
- Malaria Elimination Initiative, University of California, 550 16th street, San Francisco, CA, 94158, USA
- University of Notre Dame, Notre Dame, IN, 46556, USA
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Maasayi MS, Machange JJ, Kamande DS, Kibondo UA, Odufuwa OG, Moore SJ, Tambwe MM. The MTego trap: a potential tool for monitoring malaria and arbovirus vectors. Parasit Vectors 2023; 16:212. [PMID: 37370169 DOI: 10.1186/s13071-023-05835-9] [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: 04/01/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023] Open
Abstract
BACKGROUND Odour-baited traps are useful for vector surveillance and control. However, most existing traps have shown inconsistent recapture rates across different mosquito species, necessitating the need for more effective and efficient traps. The MTego trap with integrated thermal stimuli has been developed as an alternative trap. This study was undertaken to determine and compare the efficacy of the MTego trap to that of the Biogents (BG) modular BG-Pro (BGP) trap for sampling different mosquito species in a semi-field system. METHODS Fully balanced Latin square design experiments (no-choice and dual choice) were conducted in semi-field chambers using laboratory-reared female Anopheles gambiae sensu stricto, Anopheles funestus, Anopheles arabiensis, Culex quinquefasciatus and Aedes aegypti. There were 16 replicates, and 50 mosquitoes of each species were released in each chamber per replicate. The evaluated traps were as follows: the MTego trap baited with PM6 (MT-PM6), the MTego trap baited with BG-Lure (BGL) (MT-BGL), and the BGP trap baited with BG-Lure (BGP-BGL). RESULTS In the no-choice test, the MT-BGL and BGP-BGL traps captured a similar proportion of An. gambiae (31% vs 29%, P-value = 0.519) and An. funestus (32% vs 33%, P = 0.520). The MT-PM6 and BGP-BGL traps showed no significant difference in capturing Ae. aegypti (33% vs 31%, P = 0.324). However, the BGP-BGL caught more An. arabiensis and Cx. quinquefasciatus mosquitoes than the other traps (P < 0.0001). In the dual-choice test of MT-PM6 vs BGP-BGL, similar proportions of An. funestus (25% vs 27%, P = 0.473) and Ae. aegypti (29% vs 25%, P = 0.264) were captured in the traps, while the BGP-BGL captured more An. gambiae, An. arabiensis and Cx. quinquefasciatus mosquitoes than the MT-PM6 (P < 0.0001). CONCLUSIONS This study demonstrated that the MTego trap has potential as a tool that can be used interchangeably with the BGP trap for sampling anthropophilic mosquitoes including African malaria vectors An. gambiae and An. funestus and the principal arbovirus vector Ae. aegypti.
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Affiliation(s)
- Masudi Suleiman Maasayi
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania.
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Arusha, Tanzania.
| | - Jane Johnson Machange
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Arusha, Tanzania
| | - Dismas S Kamande
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Arusha, Tanzania
| | - Ummi Abdul Kibondo
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
| | - Olukayode G Odufuwa
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
- Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
| | - Sarah Jane Moore
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Arusha, Tanzania
- Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
| | - Mgeni Mohamed Tambwe
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
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Seavey CE, Doshi M, Colamarino A, Kim BN, Dickerson AK, Willenberg BJ. Graded Atmospheres of Volatile Pyrethroid Overlaid on Host Cues Can Be Established and Quantified Within a Novel Flight Chamber for Mosquito Behavior Studies. ENVIRONMENTAL ENTOMOLOGY 2023; 52:197-209. [PMID: 36794837 DOI: 10.1093/ee/nvad007] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Indexed: 06/18/2023]
Abstract
Spatial repellents are emerging as a promising approach to reduce vector-disease burden; however, the evolution of genetically resistant mosquitoes decreases repellent efficacy. The development of flight chambers to investigate spatial repellent application techniques is vital for sustainable mosquito control. We present an air-dilution chamber as a novel bioassay to study mosquito flight behavior responses to chemical gradients of the volatile, pyrethroid transfluthrin (TF). Air dilution was used to simulate a larger environment of stable concentration gradients verified with carbon dioxide (CO2) which was homogenously delivered and measured across the chamber to achieve a 5× inlet/outlet [CO2] ratio with 0.17 m/s outlet velocity. Female Aedes (Ae.) aegypti (Diptera: Culicidae, Linnaeus, 1762) were exposed to volatilized TF paired with heat, CO2, and Biogents-Sweetscent host-cues. Tandem solvent extraction-gas chromatography-mass spectrometry (SE-GC-MS) was used to quantify air samples taken during TF emanations with a limit of detection (LOD) and quantification (LOQ) of 2 ± 1 and 5 ± 2 parts-per-trillion (ppt) TF, respectively. Homogenous air diluted emanation of the spatial repellent TF was at least twice that of the 5× CO2 gradient with the same air flow in the chamber. The airborne TF concentrations the mosquitoes were exposed to range from 1 to 170 ppt. Video recordings of mosquito behavior during host-cues exposure revealed increased inlet activity, while exposure to TF protected host resulted in decreased inlet activity over time with inlet-outlet mosquito positional variation. This novel flight chamber design can simulate 'long'-range exposure with simultaneous quantitation of airborne spatial repellent to understand dose-dependent effects on mosquito behavior.
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Affiliation(s)
- Corey E Seavey
- University of Central Florida, College of Medicine, Department of Internal Medicine, FL 32827, USA
| | - Mona Doshi
- University of Central Florida, College of Medicine, Department of Internal Medicine, FL 32827, USA
| | - Angelo Colamarino
- University of Central Florida, College of Medicine, Department of Internal Medicine, FL 32827, USA
| | - Brian N Kim
- University of Central Florida, College of Engineering and Computer Science, Department of Electrical and Computer Engineering, FL 32816, USA
| | - Andrew K Dickerson
- Tickle College of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, TN 37996, USA
| | - Bradley J Willenberg
- University of Central Florida, College of Medicine, Department of Internal Medicine, FL 32827, USA
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11
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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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12
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Tambwe MM, Kibondo UA, Odufuwa OG, Moore J, Mpelepele A, Mashauri R, Saddler A, Moore SJ. Human landing catches provide a useful measure of protective efficacy for the evaluation of volatile pyrethroid spatial repellents. Parasit Vectors 2023; 16:90. [PMID: 36882842 PMCID: PMC9993701 DOI: 10.1186/s13071-023-05685-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 01/25/2023] [Indexed: 03/09/2023] Open
Abstract
BACKGROUND The human landing catch (HLC) method, in which human volunteers collect mosquitoes that land on them before they can bite, is used to quantify human exposure to mosquito vectors of disease. Comparing HLCs in the presence and absence of interventions such as repellents is often used to measure protective efficacy (PE). Some repellents have multiple actions, including feeding inhibition, whereby mosquitoes may be unable to bite even if they land on a host. A comparison was made between the PE of the volatile pyrethroid spatial repellent (VPSR) transfluthrin determined using a landing method (HLC) and a biting method (allowing the mosquitoes that landed to blood-feed) to evaluate whether HLC is a suitable method for the estimation of the personal PE of a VPSR. METHODS A fully balanced, two-arm crossover design study was conducted using a 6 × 6 × 2-m netted cage within a semi-field system. Hessian strips (4 m × 0.1 m) treated with a 5-, 10-, 15-, or 20-g dose of transfluthrin were evaluated against a paired negative control for three strains of laboratory-reared Anopheles and Aedes aegypti mosquitoes. Six replicates were performed per dose using either the landing or the biting method. The number of recaptured mosquitoes was analysed by negative binomial regression, and the PEs calculated using the two methods were compared by Bland-Altman plots. RESULTS For Anopheles, fewer mosquitoes blood-fed in the biting arm than landed in the landing arm (incidence rate ratio = 0.87, 95% confidence interval 0.81-0.93, P < 0.001). For Ae. aegypti, biting was overestimated by around 37% with the landing method (incidence rate ratio = 0.63, 95% confidence interval 0.57-0.70, P = 0.001). However, the PEs calculated for each method were in close agreement when tested by the Bland Altman plot. CONCLUSIONS The HLC method led to underestimation of mosquito feeding inhibition as a mode of action of transfluthrin, and there were species- and dose-dependent differences in the relationship between landing and biting. However, the estimated PEs were similar between the two methods. The results of this study indicate that HLC can be used as a proxy for personal PE for the evaluation of a VPSR, especially when the difficulties associated with enumerating blood-fed mosquitoes in a field setting are taken into consideration.
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Affiliation(s)
- Mgeni Mohamed Tambwe
- Vector Control Product Testing Unit, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania. .,Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwill, Basel, Switzerland. .,University of Basel, Petersplatz 1, 4001, Basel, Switzerland.
| | - Ummi Abdul Kibondo
- Vector Control Product Testing Unit, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
| | - Olukayode Ganiu Odufuwa
- Vector Control Product Testing Unit, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania.,Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwill, Basel, Switzerland.,University of Basel, Petersplatz 1, 4001, Basel, Switzerland.,London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Jason Moore
- Vector Control Product Testing Unit, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania.,Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwill, Basel, Switzerland.,University of Basel, Petersplatz 1, 4001, Basel, Switzerland
| | - Ahmed Mpelepele
- Vector Control Product Testing Unit, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
| | - Rajabu Mashauri
- Vector Control Product Testing Unit, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
| | | | - Sarah Jane Moore
- Vector Control Product Testing Unit, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania.,Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwill, Basel, Switzerland.,University of Basel, Petersplatz 1, 4001, Basel, Switzerland.,Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Tengeru, Tanzania
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13
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Barrera R. New tools for Aedes control: mass trapping. CURRENT OPINION IN INSECT SCIENCE 2022; 52:100942. [PMID: 35667560 PMCID: PMC9413017 DOI: 10.1016/j.cois.2022.100942] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 05/10/2022] [Accepted: 05/25/2022] [Indexed: 05/15/2023]
Abstract
Aedes aegypti, the main vector of dengue, chikungunya, and Zika viruses uses artificial containers around homes to undergo immature development, making household-level detection and control extremely difficult in large urban areas. Mass trapping is an emerging methodology to control container-Aedes species such as Aedes aegypti and Aedes albopictus because effective traps for adult stages of these mosquitoes were developed recently. There are three main approaches to mass-trapping these mosquitoes: 1) Pull (attract/kill), 2) push (repel)-pull (attract/kill), and 3) pull (attract/contaminate/infect)-push (fly away). Effective mass-trapping depends on trap quality (capture efficiency, sturdiness, frequency of servicing), trap density and areal coverage, community involvement, and safety. Recent studies showed that Ae. aegypti populations can be sustainably controlled by mass trapping, although more area-wide studies showing effectiveness at preventing disease are needed for all trapping systems. Cost-effectiveness studies are needed for all emerging Aedes control approaches.
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Affiliation(s)
- Roberto Barrera
- Entomology and Ecology Team, Dengue Branch, DBVD, NCEZID, Centers for Disease Control and Prevention (CDC), 1324 Calle Cañada, San Juan 00920, Puerto Rico.
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14
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Sirisopa P, Sukkanon C, Bangs MJ, Nakasathien S, Hii J, Grieco JP, Achee NL, Manguin S, Chareonviriyaphap T. Scientific achievements and reflections after 20 years of vector biology and control research at the Pu Teuy mosquito field research station, Thailand. Malar J 2022; 21:44. [PMID: 35164748 PMCID: PMC8842738 DOI: 10.1186/s12936-022-04061-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Accepted: 01/23/2022] [Indexed: 01/25/2023] Open
Abstract
Additional vector control tools are needed to supplement current strategies to achieve malaria elimination and control of Aedes-borne diseases in many settings in Thailand and the Greater Mekong Sub-region. Within the next decade, the vector control community, Kasetsart University (KU), and the Ministry of Higher Education, Science, Research and Innovation must take full advantage of these tools that combine different active ingredients with different modes of action. Pu Teuy Mosquito Field Research Station (MFRS), Department of Entomology, Faculty of Agriculture, Kasetsart University (KU), Thailand was established in 2001 and has grown into a leading facility for performing high-quality vector biology and control studies and evaluation of public health insecticides that are operationally relevant. Several onsite mosquito research platforms have been established including experimental huts, a 40-m long semi-field screening enclosure, mosquito insectary, field-laboratory, and living quarters for students and researchers. Field research and assessments ranged from 'basic' investigations on mosquito biology, taxonomy and genetics to more 'applied' studies on responses of mosquitoes to insecticides including repellency, behavioural avoidance and toxicity. In the course of two decades, 51 peer-reviewed articles have been published, and 7 masters and 16 doctoral degrees in Entomology have been awarded to national and international students. Continued support of key national stakeholders will sustain MFRS as a Greater Mekong Subregion centre of excellence and a resource for both insecticide trials and entomological research.
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Affiliation(s)
- Patcharawan Sirisopa
- grid.9723.f0000 0001 0944 049XDepartment of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, 10900 Thailand
| | - Chutipong Sukkanon
- grid.412867.e0000 0001 0043 6347Department of Medical Technology, School of Allied Health Sciences, Walailak University, Nakhon Si Thammarat, 80160 Thailand
| | - Michael J. Bangs
- grid.9723.f0000 0001 0944 049XDepartment of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, 10900 Thailand
| | - Sutkhet Nakasathien
- grid.9723.f0000 0001 0944 049XDepartment of Agronomy, Faculty of Agriculture, Kasetsart University, Bangkok, 10900 Thailand
| | - Jeffrey Hii
- grid.1011.10000 0004 0474 1797College of Public Health, Medical and Veterinary Sciences, James Cook University, North Queensland, QLD 4810 Australia
| | - John P. Grieco
- grid.131063.60000 0001 2168 0066Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN USA
| | - Nicole L. Achee
- grid.131063.60000 0001 2168 0066Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN USA
| | - Sylvie Manguin
- grid.463853.f0000 0004 0384 4663HSM, Univ. Montpellier, CNRS, IRD, IMT, Montpellier, France
| | - Theeraphap Chareonviriyaphap
- grid.9723.f0000 0001 0944 049XDepartment of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, 10900 Thailand
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15
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To Kill or to Repel Mosquitoes? Exploring Two Strategies for Protecting Humans and Reducing Vector-Borne Disease Risks by Using Pyrethroids as Spatial Repellents. Pathogens 2021; 10:pathogens10091171. [PMID: 34578203 PMCID: PMC8471886 DOI: 10.3390/pathogens10091171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 09/01/2021] [Accepted: 09/07/2021] [Indexed: 11/29/2022] Open
Abstract
Although control efforts are improving, vector-borne diseases remain a global public health challenge. There is a need to shift vector control paradigms while developing new products and programmes. The importance of modifying vector behaviour has been recognised for decades but has received limited attention from the public health community. This study aims to: (1) explore how the use of spatial repellents at sublethal doses could promote public health worldwide; (2) propose new methods for evaluating insecticides for use by the general public; and (3) identify key issues to address before spatial repellents can be adopted as complementary vector control tools. Two field experiments were performed to assess the effects of an insecticidal compound, the pyrethroid transfluthrin, on Aedes albopictus mosquitoes. The first examined levels of human protection, and the second looked at mosquito knockdown and mortality. For the same transfluthrin dose and application method, the percent protection remained high (>80%) at 5 h even though mosquito mortality had declined to zero at 1 h. This result underscores that it matters which evaluation parameters are chosen. If the overarching goal is to decrease health risks, sublethal doses could be useful as they protect human hosts even when mosquito mortality is null.
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Tambwe MM, Saddler A, Kibondo UA, Mashauri R, Kreppel KS, Govella NJ, Moore SJ. Semi-field evaluation of the exposure-free mosquito electrocuting trap and BG-Sentinel trap as an alternative to the human landing catch for measuring the efficacy of transfluthrin emanators against Aedes aegypti. Parasit Vectors 2021; 14:265. [PMID: 34016149 PMCID: PMC8138975 DOI: 10.1186/s13071-021-04754-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 04/28/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The human landing catch (HLC) measures human exposure to mosquito bites and evaluates the efficacy of vector control tools. However, it may expose volunteers to potentially infected mosquitoes. The mosquito electrocuting trap (MET) and BG-Sentinel traps (BGS) represent alternative, exposure-free methods for sampling host-seeking mosquitoes. This study investigates whether these methods can be effectively used as alternatives to HLC for measuring the efficacy of transfluthrin emanator against Aedes aegypti. METHODS The protective efficacy (PE) of freestanding passive transfluthrin emanators (FTPEs), measured by HLC, MET and BGS, was compared in no-choice and choice tests. The collection methods were conducted 2 m from an experimental hut with FTPEs positioned at 3 m on either side of them. For the choice experiment, a competitor HLC was included 10 m from the first collection point. One hundred laboratory-reared Ae. aegypti mosquitoes were released and collected for 3 consecutive h. RESULTS In the no-choice test, each method measured similar PE: HLC: 66% (95% confidence interval [CI]: 50-82), MET: 55% (95% CI: 48-63) and BGS: 64% (95% CI: 54-73). The proportion of mosquitoes recaptured was consistent between methods (20-24%) in treatment and varied (47-71%) in the control. However, in choice tests, the PE measured by each method varied: HLC: 37% (95% CI: 25-50%), MET: 76% (95% CI: 61-92) and BGS trap: 0% (95% CI: 0-100). Recaptured mosquitoes were no longer consistent between methods in treatment (2-26%) and remained variable in the control (7-42%). FTPE provided 50% PE to the second HLC 10 m away. In the control, the MET and the BGS were less efficacious in collecting mosquitoes in the presence of a second HLC. CONCLUSIONS Measuring the PE in isolation was fairly consistent for HLC, MET and BGS. Because HLC is not advisable, it is reasonable to use either MET or BGS as a proxy for HLC for testing volatile pyrethroid (VP) in areas of active arbovirus-endemic areas. The presence of a human host in close proximity invalidated the PE estimates from BGS and METs. Findings also indicated that transfluthrin can protect multiple people in the peridomestic area and that at short range mosquitoes select humans over the BGS.
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Affiliation(s)
- Mgeni M. Tambwe
- Vector Control Product Testing Unit, Ifakara Health Institute, Environmental Health and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania
- Swiss Tropical & Public Health Institute, Socinstrasse 57, 4051 Basel, Switzerland
- University of Basel, Petersplatz 1, 4001 Basel, Switzerland
| | - Adam Saddler
- Vector Control Product Testing Unit, Ifakara Health Institute, Environmental Health and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania
- Swiss Tropical & Public Health Institute, Socinstrasse 57, 4051 Basel, Switzerland
- University of Basel, Petersplatz 1, 4001 Basel, Switzerland
- Telethon Kids Institute, Perth, Australia
| | - Ummi Abdul Kibondo
- Vector Control Product Testing Unit, Ifakara Health Institute, Environmental Health and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania
| | - Rajabu Mashauri
- Vector Control Product Testing Unit, Ifakara Health Institute, Environmental Health and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania
| | - Katharina S. Kreppel
- Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Tengeru, Tanzania
| | - Nicodem J. Govella
- Vector Control Product Testing Unit, Ifakara Health Institute, Environmental Health and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania
- Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Tengeru, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Graham Kerr Building, Glasgow, G12 8QQ UK
| | - Sarah J. Moore
- Vector Control Product Testing Unit, Ifakara Health Institute, Environmental Health and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania
- Swiss Tropical & Public Health Institute, Socinstrasse 57, 4051 Basel, Switzerland
- University of Basel, Petersplatz 1, 4001 Basel, Switzerland
- Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Tengeru, Tanzania
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