Comparing the effectiveness of adulticide application interventions on mitigating local transmission of dengue virus

The southern US is vulnerable to importations of dengue. Understanding the effectiveness of mosquito control interventions to be employed in response to a dengue outbreak, such as adulticide spraying, are critical for mitigating the risks posed by the dengue virus (DENV). By leveraging a unique dataset of diel activity patterns of Ae. aegypti in Miami-Dade County, FL, and Brownsville, TX, we used a mechanistic model to simulate a local DENV outbreak and assess adulticide spraying interventions at varying times of day. We then performed a comparative analysis of DENV transmission dynamics produced by the model between scenarios that differ by the presence of interventions and the time of day that the interventions are implemented. We observed that spraying adulticide for 14 consecutive days at 7am or 8pm were highly effective in educing the outbreak potential (10% in the absence of interventions vs. 0.1% for Miami-Dade County; 7.8% vs. 0.1% for Brownsville) and the median number of symptomatic infections after outbreak identification (67.0 in the absence of interventions vs. 1.0 for Miami-Dade County; 15.0 vs. 1.0 for Brownsville). These findings show that adulticide application when Ae. aegypti is most active translates into a remarkable effect of in mitigating DENV transmission. Our modeling analysis provides valuable insights to inform vector control authorities on the effectiveness of adulticide spraying interventions in different contexts.