Dengue Vector Dynamics (Aedes aegypti) Influenced by Climate and Social Factors in Ecuador: Implications for Targeted Control

Raúl Mejía,Anna M. Stewart Ibarra,Ángel Muñoz,Christopher N. Mores,Efrain Beltrán,Sadie J. Ryan,Mercy Silva

doi:10.1371/journal.pone.0078263

Abstract

BackgroundDengue fever, a mosquito-borne viral disease, is now the fastest spreading tropical disease globally. Previous studies indicate that climate and human behavior interact to influence dengue virus and vector (Aedes aegypti) population dynamics; however, the relative effects of these variables depends on local ecology and social context. We investigated the roles of climate and socio-ecological factors on Ae. aegypti population dynamics in Machala, a city in southern coastal Ecuador where dengue is hyper-endemic.Methods/Principal findingsWe studied two proximate urban localities where we monitored weekly Ae. aegypti oviposition activity (Nov. 2010-June 2011), conducted seasonal pupal surveys, and surveyed household to identify dengue risk factors. The results of this study provide evidence that Ae. aegypti population dynamics are influenced by social risk factors that vary by season and lagged climate variables that vary by locality. Best-fit models to predict the presence of Ae. aegypti pupae included parameters for household water storage practices, access to piped water, the number of households per property, condition of the house and patio, and knowledge and perceptions of dengue. Rainfall and minimum temperature were significant predictors of oviposition activity, although the effect of rainfall varied by locality due to differences in types of water storage containers.ConclusionsThese results indicate the potential to reduce the burden of dengue in this region by conducting focused vector control interventions that target high-risk households and containers in each season and by developing predictive models using climate and non-climate information. These findings provide the region's public health sector with key information for conducting time and location-specific vector control campaigns, and highlight the importance of local socio-ecological studies to understand dengue dynamics. See Text S1 for an executive summary in Spanish.

Highlights

Dengue is the most widely distributed vector-borne disease in Latin America and the Caribbean, reported by 40 out of 45 countries and territories from 2000 to 2010 [1]
These results indicate the potential to reduce the burden of dengue in this region by conducting focused vector control interventions that target high-risk households and containers in each season and by developing predictive models using climate and non-climate information
Using a multi-model selection process, we tested whether household risk factors for the presence of Ae. aegypti pupae varied during different seasons; we identified the most important lagged climate variables influencing Ae. aegypti population dynamics; and we tested whether significant climate factors varied between the study localities

Summary

Introduction

Dengue is the most widely distributed vector-borne disease in Latin America and the Caribbean, reported by 40 out of 45 countries and territories from 2000 to 2010 [1]. Studies have shown that climate variability influences dengue transmission and Ae. aegypti population dynamics in the Americas, indicating the potential to develop public health interventions using climate information [2,3,4,5,6]. Rainfall events can increase mosquito abundance by increasing the availability of mosquito juvenile habitat (e.g., containers in the patio with standing water). Heavy rainfall events can decrease mosquito abundance by flushing larvae from containers [14] and drought events can increase mosquito abundance by increasing household water storage [15]. Previous studies indicate that climate and human behavior interact to influence dengue virus and vector (Aedes aegypti) population dynamics; the relative effects of these variables depends on local ecology and social context. We investigated the roles of climate and socio-ecological factors on Ae. aegypti population dynamics in Machala, a city in southern coastal Ecuador where dengue is hyper-endemic

Methods

Results

Discussion

Conclusion