Since the abandonment of Aedes aegypti eradication efforts in the late 1960's, the goal of dengue control programs has been to prevent severe forms of disease (DHF/DSS) by reducing mosquito vector populations to levels that significantly lower, but do not eliminate virus transmission. This strategy assumes a quantitative relationship between mosquito densities and intensity of dengue transmission which has never been tested. The objective of this project is to determine the nature of that relationship. That is, to measure directly dengue transmission rates after lowering mosquito population densities to levels between minimum (elimination) and maximum (no effect) thresholds. We will use traditional and novel entomological surveillance techniques to monitor mosquito populations and measure serological conversion against dengue viruses in cohorts of Peruvian school children as an index of dengue transmission. We will characterize the relationship between Ae. aegypti abundance and dengue seroconversion rates with multiple logistic regression analyses. Using entomological data on container type and indices of adult mosquito density and seroprevalence data, we will parameterize a dengue computer simulation model that integrates site specific information on mosquitoes with human age structure, human seroprevalence rates, and weather data. Using the model, we will estimate mosquito density thresholds and the effects of mosquito population reductions on dengue risk. Because, nearly all factors influencing dengue transmission are believed to vary spatially, all data gathered in our study will be indexed geographically. We will use kriging techniques to characterize spatial patterns in parameters and to develop interpolated maps for mosquito abundance and dengue risk. The first 2 years of our study will be devoted to gathering entomological and serological data, indexing geographic information, and characterizing the existing spatial patterns of mosquito abundance and dengue transmission. During subsequent years, we will quantify the effects of vector control interventions on incidence of infection. Our study will (1) be the first to test directly the entomological thresholds of dengue transmission, (2) be the first to examine empirically the relationship between mosquito density and dengue virus transmission, and (3) have direct application to control of dengue worldwide.
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