Abstract
BackgroundAedes aegypti is an important vector for arboviroses and widely distributed throughout the world. Climatic factors can influence vector population dynamics and, consequently, disease transmission. The aim of this study was to characterize the temporal dynamics of an Ae. aegypti population and dengue cases and to investigate the relationship between meteorological variables and mosquito infestation.MethodsWe monitored and analyzed the adult female Ae. aegypti population, the dengue-fever vector, in Porto Alegre, a subtropical city in Brazil using the MI-Dengue system (intelligent dengue monitoring). This system uses sticky traps to monitor weekly infestation indices. We fitted generalized additive models (GAM) with climate variables including precipitation, temperature and humidity, and a GAM that additionally included mosquito abundance in the previous week as an explanatory variable. Logistic regression was used to evaluate the effect of adult mosquito infestation on the probability of dengue occurrence.ResultsAdult mosquito abundance was strongly seasonal, with low infestation indices during the winters and high infestation during the summers. Weekly minimum temperatures above 18 °C were strongly associated with increased mosquito abundance, whereas humidity above 75% had a negative effect on abundance. The GAM model that included adult mosquito infestation in the previous week adjusted and predicted the observed data much better than the model which included only meteorological predictor variables. Dengue was also seasonal and 98% of all cases occurred at times of high adult Ae. aegypti infestation. The probability of dengue occurrence increased by 25%, when the mean number of adult mosquitos caught by monitoring traps increased by 0.1 mosquitoes per week.ConclusionsThe results suggest that continuous monitoring of dengue vector population allows for more reliable predictions of infestation indices. The adult mosquito infestation index was a good predictor of dengue occurrence. Weekly adult dengue vector monitoring is a helpful dengue control strategy in subtropical Brazilian cities.
Highlights
Aedes aegypti is an important vector for arboviroses and widely distributed throughout the world
We examined how the dengue vector density affects the probability of the occurrence of dengue infections
In this study, we found that minimum temperature, humidity and previous Ae. aegypti vector density are important factors affecting the temporal pattern of vector abundance in a region of subtropical humid climate in Brazil
Summary
Aedes aegypti is an important vector for arboviroses and widely distributed throughout the world. Climatic factors can influence vector population dynamics and, disease transmission. The disease has expanded geographically in recent years, so that all four dengue virus serotypes (DENV 1–4) are circulating in Asia, Africa and the Americas [4], and autochthonous dengue transmission has recently reached southern regions of North America and Europe [5, 6]. Predicted climate change scenarios favour a considerable increase of dengue incidence in southern Europe, especially the coastal regions [8] and an increased global distribution of the principal vector Ae. aegypti in areas that are currently considered to be unfavorable for this species [9]
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