Abstract
Management of vector population is a commonly used method for mitigating transmission of mosquito-borne infections, but quantitative information on its practical public health impact is scarce. We study the effectiveness of Ultra-Low Volume (ULV) insecticide spraying in public spaces for preventing secondary dengue virus (DENV) cases in Porto Alegre, a non-endemic metropolitan area in Brazil. We developed a stochastic transmission model based on detailed entomological, epidemiological and population data, accounting for the geographical distribution of mosquitoes and humans in the study area and spatial transmission dynamics. The model was calibrated against the distribution of DENV cluster sizes previously estimated from the same geographical setting. We estimated a ULV-induced mortality of 40% for mosquitoes and found that the implemented control protocol avoided about 24% of symptomatic cases occurred in the area throughout the 2015–2016 epidemic season. Increasing the radius of treatment or the mortality of mosquitoes by treating gardens and/or indoor premises would greatly improve the result of control, but trade-offs with respect to increased efforts need to be carefully analyzed. We found a moderate effectiveness for ULV-spraying in public areas, mainly due to the limited ability of this strategy in effectively controlling the vector population. These results can be used to support the design of control strategies in low-incidence, non-endemic settings.
Highlights
Dengue virus (DENV) causes a considerable burden to public health worldwide, consisting of 60 to 100 million symptomatic infections, 14,000 to 20,000 deaths per year, and of a global annual cost of about 9 billion dollars [1, 2]
DENV is expanding its geographic range to areas that were previously free from autochthonous transmission and are prone to multiple outbreaks each year
In non-endemic settings, the main strategy for DENV control consists in the management of vector populations via insecticide spraying as a reactive intervention to ongoing local transmission
Summary
Dengue virus (DENV) causes a considerable burden to public health worldwide, consisting of 60 to 100 million symptomatic infections, 14,000 to 20,000 deaths per year, and of a global annual cost of about 9 billion dollars [1, 2]. In non-endemic settings, the main strategy for DENV control consists in the management of vector populations via insecticide spraying as a reactive intervention to ongoing local transmission Despite its popularity, this practice has been rarely evaluated in terms of its impact on DENV transmission in real-life settings [13, 14]. Spatial transmission models are another common epidemiological tool that has been used to study DENV control in different parts of the world [21, 22, 25,26,27] We combine these approaches with recent insights on the spatiotemporal dynamics of DENV [16], to estimate the proportion of cases avoided by Ultra-Low-Volume (ULV) insecticide spraying in Porto Alegre, a Brazilian metropolis characterized by a subtropical climate, low DENV incidence and negligible pre-existing immunity
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
