Volatile pyrethroid spatial repellents for preventing mosquito bites: a systematic review and meta-analysis

Ingrid Chen¹, Sarah L Miller², Daniel Msellemu³, Aidi G Lugenge³, Johnson Kyeba Swai³, Nicole Achee⁴, Marta Andrés⁵, Christopher S Bibbs⁶, Theeraphap Chareonviriyaphap⁷, J Derek Charlwood⁸, Greg Devine⁹, Noel Elman¹⁰, Ulrike Fillinger¹¹, Carmen Flores-Mendoza¹², Seth Gibson¹³, Nicodem Govella³, Steven Gowelo¹⁴, Sebastian Horstmann¹⁵, Hitoshi Kawada¹⁶, Daniel Kline¹³, Aaron Lloyd¹⁷, Neil F Lobo¹⁸, Marta F Maia¹⁹, Arnold Mmbando²⁰, Mara Moreno-Gómez²¹, Amy C Morrison²², Winifrida Mponzi²³, Emmanuel P Mwanga²³, Margaret Njoroge²⁴, Sheila B Ogoma²⁵, Fredros O Okumu²⁶, Mercy Opiyo¹⁴, Welbeck A Oumbouke²⁷, John Paliga³, Arissara Pongsiri²², Alongkot Ponlawat²², Manop Saeaung⁷, Ferdinand Salazar²⁸, Onyango Sangoro²³, Jennifer C Stevenson³, Chutipong Sukkanon²⁹, Din Syafruddin³⁰, Mgeni Mohamed Tambwe³, Julie-Anne A Tangena²⁷, Elodie A Vajda³¹, Gonzalo Vazquez-Prokopec³², Joseph M Wagman³³, Chanly Yan⁷, Isabel Elaine Allen², Sarah J Moore³⁴

Affiliations

¹ Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA; Malaria Elimination Initiative, Institute for Global Health Sciences, University of California, San Francisco, CA, USA. Electronic address: ingrid.chen@ucsf.edu.
² Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA.
³ Ifakara Health Institute, Bagamoyo, Tanzania.
⁴ Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA.
⁵ Ifakara Health Institute, Bagamoyo, Tanzania; University College London, London, UK; National Center National Institute for Agricultural and Food Research and Technology, Spanish National Research Council, Valdeolmos, Spain.
⁶ Salt Lake City Mosquito Abatement District, Salt Lake City, UT, USA.
⁷ Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand.
⁸ Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Novo de Lisboa, Lisbon, Portugal.
⁹ QIMR Berghofer Medical Research Institute, Herston, Australia.
¹⁰ GearJump Technologies LLC, Boston, MA, USA.
¹¹ Independent Consultant, Disease Ecology and Vector Control, Mannheim, Germany.
¹² U.S. Naval Medical Research Unit SOUTH, Lima, Peru.
¹³ U.S. Department of Agriculture, Agricultural Research Service, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL, USA.
¹⁴ Malaria Elimination Initiative, Institute for Global Health Sciences, University of California, San Francisco, CA, USA.
¹⁵ Envu, 2022 ES Deutschland GmbH, Monheim am Rhein, Germany.
¹⁶ Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan.
¹⁷ Lee County Mosquito Control District, Buckingham, FL, USA.
¹⁸ Malaria Elimination Initiative, Institute for Global Health Sciences, University of California, San Francisco, CA, USA; Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA.
¹⁹ Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK; Department of Biosciences, KEMRI Wellcome Trust Research Programme, Kilifi, Kenya.
²⁰ Ifakara Health Institute, Ifakara, Morogoro, Tanzania; Department of Biosciences, Durham University, Durham, UK.
²¹ Henkel, Barcelona, Spain.
²² Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA, USA.
²³ Ifakara Health Institute, Ifakara, Morogoro, Tanzania.
²⁴ International Centre for Insect Physiology and Ecology (icipe), Nairobi, Kenya.
²⁵ PMI VectorLink, Abt Associates, Nairobi, Kenya.
²⁶ Ifakara Health Institute, Ifakara, Morogoro, Tanzania; University of Glasgow, Glasgow, Scotland, UK.
²⁷ Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
²⁸ Department of Medical Entomology, Research Institute for Tropical Medicine, Department of Health, Alabang, Muntinlupa City, Philippines.
²⁹ Department of Clinical Microscopy, Faculty of Medical Technology, Mahidol University, Salaya, Phuttamonthon, Nakhon Pathom, Thailand.
³⁰ Department Parasitology, Faculty of Medicine, Hasanuddin University, Makassar, Indonesia.
³¹ Malaria Elimination Initiative, Institute for Global Health Sciences, University of California, San Francisco, CA, USA; Swiss Tropical and Public Health Institute, Allschwil, Switzerland.
³² Department of Environmental Sciences, Emory University, Atlanta, GA, USA.
³³ Wagman Global Health Consulting, Rockville, MD, USA.
³⁴ Ifakara Health Institute, Bagamoyo, Tanzania; Swiss Tropical and Public Health Institute, Allschwil, Switzerland.

PMID: 40866281
DOI: 10.1016/j.ebiom.2025.105891

Free article

Meta-Analysis

Volatile pyrethroid spatial repellents for preventing mosquito bites: a systematic review and meta-analysis

Ingrid Chen et al. EBioMedicine. 2025 Sep.

Free article

. 2025 Sep:119:105891.

doi: 10.1016/j.ebiom.2025.105891. Epub 2025 Aug 26.

Authors

Affiliations

¹ Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA; Malaria Elimination Initiative, Institute for Global Health Sciences, University of California, San Francisco, CA, USA. Electronic address: ingrid.chen@ucsf.edu.
² Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA.
³ Ifakara Health Institute, Bagamoyo, Tanzania.
⁴ Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA.
⁵ Ifakara Health Institute, Bagamoyo, Tanzania; University College London, London, UK; National Center National Institute for Agricultural and Food Research and Technology, Spanish National Research Council, Valdeolmos, Spain.
⁶ Salt Lake City Mosquito Abatement District, Salt Lake City, UT, USA.
⁷ Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand.
⁸ Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Novo de Lisboa, Lisbon, Portugal.
⁹ QIMR Berghofer Medical Research Institute, Herston, Australia.
¹⁰ GearJump Technologies LLC, Boston, MA, USA.
¹¹ Independent Consultant, Disease Ecology and Vector Control, Mannheim, Germany.
¹² U.S. Naval Medical Research Unit SOUTH, Lima, Peru.
¹³ U.S. Department of Agriculture, Agricultural Research Service, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL, USA.
¹⁴ Malaria Elimination Initiative, Institute for Global Health Sciences, University of California, San Francisco, CA, USA.
¹⁵ Envu, 2022 ES Deutschland GmbH, Monheim am Rhein, Germany.
¹⁶ Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan.
¹⁷ Lee County Mosquito Control District, Buckingham, FL, USA.
¹⁸ Malaria Elimination Initiative, Institute for Global Health Sciences, University of California, San Francisco, CA, USA; Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA.
¹⁹ Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK; Department of Biosciences, KEMRI Wellcome Trust Research Programme, Kilifi, Kenya.
²⁰ Ifakara Health Institute, Ifakara, Morogoro, Tanzania; Department of Biosciences, Durham University, Durham, UK.
²¹ Henkel, Barcelona, Spain.
²² Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA, USA.
²³ Ifakara Health Institute, Ifakara, Morogoro, Tanzania.
²⁴ International Centre for Insect Physiology and Ecology (icipe), Nairobi, Kenya.
²⁵ PMI VectorLink, Abt Associates, Nairobi, Kenya.
²⁶ Ifakara Health Institute, Ifakara, Morogoro, Tanzania; University of Glasgow, Glasgow, Scotland, UK.
²⁷ Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
²⁸ Department of Medical Entomology, Research Institute for Tropical Medicine, Department of Health, Alabang, Muntinlupa City, Philippines.
²⁹ Department of Clinical Microscopy, Faculty of Medical Technology, Mahidol University, Salaya, Phuttamonthon, Nakhon Pathom, Thailand.
³⁰ Department Parasitology, Faculty of Medicine, Hasanuddin University, Makassar, Indonesia.
³¹ Malaria Elimination Initiative, Institute for Global Health Sciences, University of California, San Francisco, CA, USA; Swiss Tropical and Public Health Institute, Allschwil, Switzerland.
³² Department of Environmental Sciences, Emory University, Atlanta, GA, USA.
³³ Wagman Global Health Consulting, Rockville, MD, USA.
³⁴ Ifakara Health Institute, Bagamoyo, Tanzania; Swiss Tropical and Public Health Institute, Allschwil, Switzerland.

PMID: 40866281
DOI: 10.1016/j.ebiom.2025.105891

Abstract

Background: Volatile pyrethroid spatial repellents (VPSRs) can prevent mosquito-borne diseases including malaria and dengue fever, but the use of varied evaluation methods has resulted in a lack of clarity regarding their protective efficacy (PE) against contact with mosquitoes. This systematic review and meta-analysis consolidates the entomological evidence base on the PE of VPSRs against Anopheles, Aedes, and Culex mosquitoes and different test methods used.

Methods: We identified studies completed between January 2000 and September 2023 by searching through databases, conference abstracts, and personal correspondences. Included studies were semi-field or field studies that measured the PE of VPSRs using human landing catch (HLC) of mosquito landings on human legs and/or mosquito trap density, the number of mosquitoes captured using traps per set time period, compared to control groups. The systematic review summarised study-level data using a generalised linear mixed model with random effects. The meta-analysis pooled individual mosquito-level data and weather data on temperature, humidity, and wind from satellites, analysing PE subgrouped by product format, active ingredient, mosquito capture method used, mosquito species, and indoor vs outdoor setting. Risk of bias was assessed using a SYRCLE tool adapted for mosquito studies. Additional studies published from October 2023 to July 2025 were summarised. PROSPERO registration: CRD42021268852.

Findings: 58 eligible publications showed that VPSRs provided an average of 56% (95% CI 50, 62%) PE from mosquito bites. Meta-analysis of individual mosquito-level data from 50 (86%) of eligible studies involving 1,703,120 mosquitoes showed that PE was highest when measured using HLC, with similar results seen in semi-field (58%, 95% CI 54, 62%) and field studies (50%, 95% CI 40, 59%). Differences between indoor (54%, 95% CI 18, 68%) and outdoor settings (56%, 95% CI 51, 60%) were unclear. Species-level differences were observed with low PE seen in Anopheles funestus (31%, 95% CI 19, 43%); the potential for cross-resistance to solid-state pyrethroids is unclear. Efficacy was not sensitive to combined weather effects.

Interpretation: VPSRs offer protection from contact with mosquitoes, with semi-field studies reflecting field data and species-level differences observed. HLC provided the best quality data. Additional field studies that evaluate outdoor protection in malaria-endemic settings are needed, especially in West African, South American, and Southeast Asian settings.

Funding: National Institutes of Health (National Institute of Allergy and Infectious Diseases (K01AI156182)) and "Accelerate to Eliminate Malaria" program.

Keywords: Meta-analysis; Mosquito; Spatial emanator; Spatial repellent; Vector control; Volatile pyrethroid.

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Conflict of interest statement

Declaration of interests JKS received research funds through the Ifakara Health Institute to conduct product evaluation on spatial repellents, NA received a Unitaid grant to the University of Notre Dame to conduct research on spatial repellents, CSB received payments to the University of Florida to fund mosquito research on spatial repellent development, NE received grants from the U.S. Department of Defense and U.S. Military Infectious Diseases Research Program to conduct research on spatial repellents, SH is an employee of Envu (2022 ES Deutschland GmbH) but does not have a conflict of interest with the study because he was not involved in data collection or analysis, NFL received a Unitaid grant on spatial repellents, and ACM is on an advisory board to the Peruvian Ministry of Health on dengue and vector control. SJM has service contracts for spatial repellent research from SC Johnson, Envu, Sumitomo, and Widder Bros. All other authors declare no conflicts of interest related to this study.

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Volatile pyrethroid spatial repellents for preventing mosquito bites: a systematic review and meta-analysis

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Volatile pyrethroid spatial repellents for preventing mosquito bites: a systematic review and meta-analysis

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