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PLoS Negl Trop Dis

Title:		Community deployment of a synthetic pheromone of the sand fly Lutzomyia longipalpis co-located with insecticide reduces vector abundance in treated and neighbouring untreated houses: Implications for control of Leishmania infantum
Author(s):		Goncalves R; de Souza CF; Rontani RB; Pereira A; Farnes KB; Gorsich EE; Silva RA; Brazil RP; Hamilton JGC; Courtenay O;
Address:		"Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom. Laboratorio de Doencas Parasitarias, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil. Nucleo de Medicina Tropical, Universidade de Brasilia, Brasilia, Federal District, Brazil. Ministerio da Saude, Departamento de Imunizacao e Doencas Transmissiveis, Secretaria de Vigilancia em Saude, Brasilia, Federal District, Brazil. Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Bailrigg, Lancaster, Lancashire, United Kingdom"
Journal Title:		PLoS Negl Trop Dis
Year:		2021
Volume:		20210203
Issue:		2
Page Number:		e0009080 -
DOI:		10.1371/journal.pntd.0009080
ISSN/ISBN:		1935-2735 (Electronic) 1935-2727 (Print) 1935-2727 (Linking)
Abstract:		"BACKGROUND: The rising incidence of visceral leishmaniasis due to Leishmania infantum requires novel methods to control transmission by the sand fly vector. Indoor residual spraying of insecticide (IRS) against these largely exophilic / exophagic vectors may not be the most effective method. A synthetic copy of the male sex-aggregation pheromone of the key vector species Lutzomyia longipalpis in the Americas, was co-located with residual pyrethroid insecticide, and tested for its effects on vector abundance, hence potential transmission, in a Brazilian community study. METHODS: Houses within eight defined semi-urban blocks in an endemic municipality in Brazil were randomised to synthetic pheromone + insecticide or to placebo treatments. A similar number of houses located >100m from each block were placebo treated and considered as 'True Controls' (thus, analysed as three trial arms). Insecticide was sprayed on a 2.6m2 surface area of the property boundary or outbuilding wall, co-located within one metre of 50mg synthetic pheromone in controlled-release dispensers. Vector numbers captured in nearby CDC light traps were recorded at monthly intervals over 3 months post intervention. Recruited sentinel houses under True Control and pheromone + insecticide treatments were similarly monitored at 7-9 day intervals. The intervention effects were estimated by mixed effects negative binomial models compared to the True Control group. RESULTS: Dose-response field assays using 50mg of the synthetic pheromone captured a mean 4.8 (95% C.L.: 3.91, 5.80) to 6.3 (95% C.L.: 3.24, 12.11) times more vectors (female Lu. longipalpis) than using 10mg of synthetic pheromone. The intervention reduced household female vector abundance by 59% (C.L.: 48.7, 66.7%) (IRR = 0.41) estimated by the cross-sectional community study, and by 70% (C.L.: 56.7%, 78.8%) estimated by the longitudinal sentinel study. Similar reductions in male Lu. longipalpis were observed. Beneficial spill-over intervention effects were also observed at nearby untreated households with a mean reduction of 24% (95% C.L.: 0.050%, 39.8%) in female vectors. The spill-over effect in untreated houses was 44% (95% C.L.: 29.7%, 56.1%) as effective as the intervention in pheromone-treated houses. Ownership of chickens increased the intervention effects in both treated and untreated houses, attributed to the suspected synergistic attraction of the synthetic pheromone and chicken kairomones. The variation in IRR between study blocks was not associated with inter-household distances, household densities, or coverage (proportion of total households treated). CONCLUSIONS: The study confirms the entomological efficacy of the lure-and-kill method to reduce the abundance of this important sand fly vector in treated and untreated homesteads. The outcomes were achieved by low coverage and using only 1-2% of the quantity of insecticide as normally required for IRS, indicating the potential cost-effectiveness of this method. Implications for programmatic deployment of this vector control method are discussed"
Keywords:		"Animals Brazil Chickens Cross-Sectional Studies Family Characteristics Female Humans Incidence Insect Control/*methods Insect Vectors/drug effects Insecticides/*pharmacology Leishmania infantum/physiology Leishmaniasis, Visceral Male Pheromones/*pharmacol;"
Notes:		"MedlineGoncalves, Raquel de Souza, Cristian F Rontani, Reila B Pereira, Alisson Farnes, Katie B Gorsich, Erin E Silva, Rafaella A Brazil, Reginaldo P Hamilton, James G C Courtenay, Orin eng WT_/Wellcome Trust/United Kingdom WT091689MF/WT_/Wellcome Trust/United Kingdom Research Support, Non-U.S. Gov't 2021/02/04 PLoS Negl Trop Dis. 2021 Feb 3; 15(2):e0009080. doi: 10.1371/journal.pntd.0009080. eCollection 2021 Feb"