title: The impact of indoor residual spraying of deltamethrin on dengue vector populations in the Peruvian Amazon.
abstract: Dengue is an important public health problem in the Amazon area of Peru, resulting in significant morbidity each year. As in other areas of the world, ultra-low volume (ULV) application of insecticides is the main strategy to reduce adult populations of the dengue vector Aedes aegypti, despite growing evidence of its limitations as a single control method. This study investigated the efficacy of deltamethrin S.C. applied through indoor residual spraying (IRS) of dwellings in reducing A. aegypti populations. The residual effect of the insecticide was tested by monthly bioassays on the three most common indoor surfaces found in the Amazon area: painted wood, unpainted wood and brick. The results showed that in an area with moderate levels of A. aegypti infestation, IRS dramatically reduced all immature indices the first week after deltamethrin IRS application and the adult index from 18.5 to 3.1, four weeks after intervention (p<0.05). Even though housing conditions facilitated reinfestation with A. aegypti (100% of the houses have open roof eaves, 31.5% lack sewage systems, and 60.4% collected rain in open containers), indices remained low compared to baseline 16 weeks after insecticide application. Bioassays showed that deltamethrin S.C. caused mortalities >80% 8 weeks after application on all types of surfaces. The residual effect of the insecticide was greater on brick than on wooden walls (p<0.05). Our results demonstrate that IRS can have both an immediate and sustained effect on reducing adult and immature A. aegypti populations and should be considered as an adult mosquito control strategy by dengue vector control programs.
authors.affiliation: Lab. Zoology, University of the Balearic Islands, Ctra de Valldemossa Km 7.5, 07122 Palma de Mallorca, Spain. Electronic address: claudia.paredes@uib.es.
authors.forename: Claudia
authors.initials: C
authors.lastname: Paredes-Esquivel
authors.affiliation: U.S. Centers for Disease Control and Prevention, Atlanta, USA.
authors.forename: Audrey
authors.initials: A
authors.lastname: Lenhart
authors.affiliation: Lab. Zoology, University of the Balearic Islands, Ctra de Valldemossa Km 7.5, 07122 Palma de Mallorca, Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: del Río
authors.affiliation: Lab. Zoology, University of the Balearic Islands, Ctra de Valldemossa Km 7.5, 07122 Palma de Mallorca, Spain.
authors.forename: M M
authors.initials: MM
authors.lastname: Leza
authors.affiliation: Lab. Zoology, University of the Balearic Islands, Ctra de Valldemossa Km 7.5, 07122 Palma de Mallorca, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Estrugo
authors.affiliation: Dirección Regional de Salud Loreto, Ministerio de Salud del Perú, Peru.
authors.forename: Enrique
authors.initials: E
authors.lastname: Chalco
authors.affiliation: Dirección Regional de Salud Loreto, Ministerio de Salud del Perú, Peru.
authors.forename: Wilma
authors.initials: W
authors.lastname: Casanova
authors.affiliation: Lab. Zoology, University of the Balearic Islands, Ctra de Valldemossa Km 7.5, 07122 Palma de Mallorca, Spain.
authors.forename: Miguel Ángel
authors.initials: MÁ
authors.lastname: Miranda
mesh_terms: D000330:Aedes / Q000187:drug effects*; D000818:Animals; D001681:Biological Assay; D003252:Construction Materials; D003715:Dengue / Q000517:prevention & control; D003716:Dengue Virus; D006798:Housing; D006801:Humans; D007303:Insect Vectors / Q000187:drug effects*; D007306:Insecticides / Q000494:pharmacology*; D009032:Mosquito Control / Q000379:methods*; D009570:Nitriles / Q000494:pharmacology*; D010568:Peru; D011634:Public Health; D011722:Pyrethrins / Q000494:pharmacology*
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin
keywords: Aedes aegypti; Dengue; IRS; Indoor residual spraying; Mosquitoes; Vector-control