Randomized Trial of a Modification of Rainwater Street Catch Basins to Physically Control the Aedes aegypti Dengue Mosquito Vector

Abstract

Dengue is the most important viral disease transmitted by mosquitoes. Ineffective vector control, cluttered urbanization, poor rainwater and wastewater management and increased air travel have encouraged the proliferation of the Aedes aegypti mosquito in Latin America, causing dengue and, more recently, zika and chikungunya, to become widespread public health problems. Vector control has targeted the reduction of breeding sites. Objective: For this reason, a randomized trial in a neighborhood of Cali, Colombia, subject to high dengue incidence was carried out. Materials and methods: Of 42 selected storm drains, 21 were randomly allocated for the installation of a filter bed that prevents water retention after a rain event (> 100 mm), with the remaining 21 being unmodified. The presence of standing water in the storm drains and the number of A. aegypti larvae were evaluated. Results and Discussion: Of the 21 modified (5 contained standing water) and unmodified storm drains (19 contained standing water), an Aedic Index (proportion positive for immature A. aegypti) of 5 % and 65 %, and a mean number of larvae per storm drain of 3.2 and 31.9, respectively, were obtained. A reduction of 90 % (p-value = 0.016) in the mean number was achieved. Conclusion: This intervention was effective against A. aegypti and is cost-effective (< $2/ inhabitant), environmentally friendly, and a sustainable strategy for the control of one of the most important breeding sites of this vector.