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Preventive residual insecticide applications successfully controlled Aedes aegypti in Yucatan, Mexico. Sci Rep 2022; 12:21998. [PMID: 36539478 PMCID: PMC9768150 DOI: 10.1038/s41598-022-26577-1] [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: 09/05/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Insecticide-based approaches remain a key pillar for Aedes-borne virus (ABV, dengue, chikungunya, Zika) control, yet they are challenged by the limited effect of traditional outdoor insecticide campaigns responding to reported arboviral cases and by the emergence of insecticide resistance in mosquitoes. A three-arm Phase II unblinded entomological cluster randomized trial was conducted in Merida, Yucatan State, Mexico, to quantify the entomological impact of targeted indoor residual spraying (TIRS, application of residual insecticides in Ae. aegypti indoor resting sites) applied preventively 2 months before the beginning of the arbovirus transmission season. Trial arms involved the use of two insecticides with unrelated modes of action (Actellic 300CS, pirimiphos-methyl, and SumiShield 50WG, clothianidin) and a control arm where TIRS was not applied. Entomological impact was quantified by Prokopack adult collections performed indoors during 10 min per house. Regardless of the insecticide, conducting a preventive TIRS application led to significant reductions in indoor Ae. aegypti densities, which were maintained at the same levels as in the low arbovirus transmission period (Actellic 300CS reduced Ae. aegypti density up to 8 months, whereas SumiShield 50WG up to 6 months). The proportional reduction in Ae. aegypti abundance in treatment houses compared to control houses was 50-70% for Actellic 300CS and 43-63% for SumiShield 50WG. Total operational costs including insecticide ranged from US$4.2 to US$10.5 per house, depending on the insecticide cost. Conducting preventive residual insecticide applications can maintain Ae. aegypti densities at low levels year-round with important implications for preventing ABVs in the Americas and beyond.
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Silalahi CN, Tu WC, Chang NT, Singham GV, Ahmad I, Neoh KB. Insecticide Resistance Profiles and Synergism of Field Aedes aegypti from Indonesia. PLoS Negl Trop Dis 2022; 16:e0010501. [PMID: 35666774 PMCID: PMC9203003 DOI: 10.1371/journal.pntd.0010501] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 06/16/2022] [Accepted: 05/16/2022] [Indexed: 12/05/2022] Open
Abstract
Information on the insecticide resistance profiles of Aedes aegypti in Indonesia is fragmentary because of the lack of wide-area insecticide resistance surveillance. We collected Ae. aegypti from 32 districts and regencies in 27 Indonesian provinces and used WHO bioassays to evaluate their resistance to deltamethrin, permethrin, bendiocarb, and pirimiphos-methyl. To determine the possible resistance mechanisms of Ae. aegypti, synergism tests were conducted using piperonyl butoxide (PBO) and S,S,S-tributylphosphorotrithioates (DEF). The Ae. aegypti from all locations exhibited various levels of resistance to pyrethroids. Their resistance ratio (RR50) to permethrin and deltamethrin ranged from 4.08× to 127× and from 4.37× to 72.20×, respectively. In contrast with the findings of other studies, most strains from the highly urbanized cities on the island of Java (i.e., Banten, Jakarta, Bandung, Semarang, Yogyakarta, and Surabaya) exhibited low to moderate resistance to pyrethroids. By contrast, the strains collected from the less populated Kalimantan region exhibited very high resistance to pyrethroids. The possible reasons are discussed herein. Low levels of resistance to bendiocarb (RR50, 1.24–6.46×) and pirimiphos-methyl (RR50, 1.01–2.70×) were observed in all tested strains, regardless of locality. PBO and DEF synergists significantly increased the susceptibility of Ae. aegypti to permethrin and deltamethrin and reduced their resistance ratio to less than 16×. The synergism tests suggested the major involvement of cytochrome P450 monooxygenases and esterases in conferring pyrethroid resistance. On the basis of our results, we proposed a 6-month rotation of insecticides (deltamethrin + synergists ➝ bendiocarb ➝ permethrin + synergists ➝ pirimiphos-methyl) and the use of an insecticide mixture containing pyrethroid and pyrimiphos-methyl to control Ae. aegypti populations and overcome the challenge of widespread Ae. aegypti resistance to pyrethroid in Indonesia. Insecticide resistance is a major impediment to the successful management of vector-transmitted diseases because it increases the vector’s chances of surviving under insecticide treatment. In Indonesia, the implementation of insecticide resistance management at the national level is particularly challenging due to the vast area and regional disparities in terms of population, health, and socioeconomic status. Previous studies on determining insecticide resistance of Aedes mosquito only focused on several cities in some provinces of Indonesia, making resistance monitoring results difficult to interpret and arguably reflect the generality in Indonesia. To complicate the matter, data released by the Ministry of Agriculture of Indonesia in 2022 showed that approximately 82% of insecticides registered to control Ae. aegypti in Indonesia are pyrethroid-based products. Principally, we found that the synergists PBO and DEF significantly reduce the resistance of field Ae. aegypti from Indonesia toward permethrin and deltamethrin. Bendiocarb and pirimiphos-methyl remain highly toxic to the field strains of Ae. aegypti. We suggest the feasible choice of insecticide group for Ae. aegypti vector management based on the currently registered insecticide inventory. The finding also underscores the urgent need to approve other non-pyrethroid-based insecticides as alternative tools for reducing the risk of resistance development during an outbreak.
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Affiliation(s)
| | - Wu-Chun Tu
- Department of Entomology, National Chung Hsing University, Taichung, Taiwan
| | - Niann-Tai Chang
- Department of Plant Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - G. Veera Singham
- Centre for Chemical Biology, Universiti Sains Malaysia, Bayan Lepas, Penang, Malaysia
| | - Intan Ahmad
- School of Life Sciences and Technology, Institut Teknologi Bandung, Bandung, West Java, Indonesia
- * E-mail: (IA); (KBN)
| | - Kok-Boon Neoh
- Department of Entomology, National Chung Hsing University, Taichung, Taiwan
- * E-mail: (IA); (KBN)
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Manrique-Saide P, Dean NE, Halloran ME, Longini IM, Collins MH, Waller LA, Gomez-Dantes H, Lenhart A, Hladish TJ, Che-Mendoza A, Kirstein OD, Romer Y, Correa-Morales F, Palacio-Vargas J, Mendez-Vales R, Pérez PG, Pavia-Ruz N, Ayora-Talavera G, Vazquez-Prokopec GM. The TIRS trial: protocol for a cluster randomized controlled trial assessing the efficacy of preventive targeted indoor residual spraying to reduce Aedes-borne viral illnesses in Merida, Mexico. Trials 2020; 21:839. [PMID: 33032661 PMCID: PMC7542575 DOI: 10.1186/s13063-020-04780-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 09/29/2020] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Current urban vector control strategies have failed to contain dengue epidemics and to prevent the global expansion of Aedes-borne viruses (ABVs: dengue, chikungunya, Zika). Part of the challenge in sustaining effective ABV control emerges from the paucity of evidence regarding the epidemiological impact of any Aedes control method. A strategy for which there is limited epidemiological evidence is targeted indoor residual spraying (TIRS). TIRS is a modification of classic malaria indoor residual spraying that accounts for Aedes aegypti resting behavior by applying residual insecticides on exposed lower sections of walls (< 1.5 m), under furniture, and on dark surfaces. METHODS/DESIGN We are pursuing a two-arm, parallel, unblinded, cluster randomized controlled trial to quantify the overall efficacy of TIRS in reducing the burden of laboratory-confirmed ABV clinical disease (primary endpoint). The trial will be conducted in the city of Merida, Yucatan State, Mexico (population ~ 1million), where we will prospectively follow 4600 children aged 2-15 years at enrollment, distributed in 50 clusters of 5 × 5 city blocks each. Clusters will be randomly allocated (n = 25 per arm) using covariate-constrained randomization. A "fried egg" design will be followed, in which all blocks of the 5 × 5 cluster receive the intervention, but all sampling to evaluate the epidemiological and entomological endpoints will occur in the "yolk," the center 3 × 3 city blocks of each cluster. TIRS will be implemented as a preventive application (~ 1-2 months prior to the beginning of the ABV season). Active monitoring for symptomatic ABV illness will occur through weekly household visits and enhanced surveillance. Annual sero-surveys will be performed after each transmission season and entomological evaluations of Ae. aegypti indoor abundance and ABV infection rates monthly during the period of active surveillance. Epidemiological and entomological evaluation will continue for up to three transmission seasons. DISCUSSION The findings from this study will provide robust epidemiological evidence of the efficacy of TIRS in reducing ABV illness and infection. If efficacious, TIRS could drive a paradigm shift in Aedes control by considering Ae. aegypti behavior to guide residual insecticide applications and changing deployment to preemptive control (rather than in response to symptomatic cases), two major enhancements to existing practice. TRIAL REGISTRATION ClinicalTrials.gov NCT04343521 . Registered on 13 April 2020. The protocol also complies with the WHO International Clinical Trials Registry Platform (ICTRP) (Additional file 1). PRIMARY SPONSOR National Institutes of Health, National Institute of Allergy and Infectious Diseases (NIH/NIAID).
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Affiliation(s)
- Pablo Manrique-Saide
- Unidad Colaborativa de Bioensayos Entomológicos, Campus de Ciencias Biológicas y Agropecuarias, Universidad Autónoma de Yucatán, Merida, Mexico
| | - Natalie E Dean
- Department of Biostatistics, University of Florida, Gainesville, FL, 32611, USA
| | - M Elizabeth Halloran
- Center for Inference and Dynamics of Infectious Diseases, Seattle, WA, 98109, USA
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
- Department of Biostatistics, University of Washington, Seattle, WA, 98109, USA
| | - Ira M Longini
- Department of Biostatistics, University of Florida, Gainesville, FL, 32611, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, 32611, USA
| | - Matthew H Collins
- Hope Clinic of the Emory Vaccine Center, Division of Infectious Diseases, Department of Medicine, School of Medicine, Emory University, Decatur, GA, 30030, USA
| | - Lance A Waller
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, GA, 30322, USA
| | - Hector Gomez-Dantes
- Health Systems Research Center, National Institute of Public Health, Cuernavaca, Mexico
| | - Audrey Lenhart
- Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Thomas J Hladish
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, 32611, USA
- Department of Biology, University of Florida, Gainesville, FL, 32611, USA
| | - Azael Che-Mendoza
- Unidad Colaborativa de Bioensayos Entomológicos, Campus de Ciencias Biológicas y Agropecuarias, Universidad Autónoma de Yucatán, Merida, Mexico
| | - Oscar D Kirstein
- Department of Environmental Sciences, Math and Science Center, Emory University, 400 Dowman Drive, 5th floor, Suite E530, Atlanta, GA, 30322, USA
| | - Yamila Romer
- Department of Environmental Sciences, Math and Science Center, Emory University, 400 Dowman Drive, 5th floor, Suite E530, Atlanta, GA, 30322, USA
| | - Fabian Correa-Morales
- Centro Nacional de Programas Preventivos y Control de Enfermedades (CENAPRECE) Secretaría de Salud Mexico, Mexico City, Mexico
| | | | | | | | - Norma Pavia-Ruz
- Centro de Investigaciones Regionales Hideyo Noguchi, Universidad Autonoma de Yucatan, Merida, Mexico
| | - Guadalupe Ayora-Talavera
- Centro de Investigaciones Regionales Hideyo Noguchi, Universidad Autonoma de Yucatan, Merida, Mexico
| | - Gonzalo M Vazquez-Prokopec
- Department of Environmental Sciences, Math and Science Center, Emory University, 400 Dowman Drive, 5th floor, Suite E530, Atlanta, GA, 30322, USA.
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