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

Abstract

The southern US has a large presence of mosquito vector species for dengue virus (DENV) and experiences thousands of DENV importations every year, which have led to several local outbreaks. Adulticide spraying targeting active mosquitoes is one of the most common insecticide strategies used as a response to an outbreak. The aim of this study is to evaluate the effectiveness of adulticide spraying conducted at different times of the day to curb DENV transmission. Based on unique dataset of Aedes aegypti diel activity patterns in Miami-Dade County, Florida, and Brownsville, Texas, we developed a mechanistic model of DENV transmission, which simulates adulticide spraying interventions. We estimated that spraying adulticide for 14 consecutive days at 7am or 8 pm was highly effective in reducing DENV outbreak probability from 10% in the absence of interventions to 0.1% for Miami-Dade County, and from 7.8 to 0.1% for Brownsville. Moreover, in case of a local outbreak in Miami-Dade County, we estimated the median number of symptomatic infections after the identification of a local outbreak to be reduced from 67.0 (IQR: 25.5–103.0) in the absence of interventions to 1.0 (IQR: 0.0–2.0) when spraying adulticide for 14 consecutive days at 8 pm. In Brownsville, the same intervention is estimated to lead to a decrease from 15.0 (IQR: 7.0–33.0) cases to 1.0 (IQR: 0.0–2.0). Our study highlights the importance of considering diel activity patterns of vector mosquito species in arbovirus preparedness and response planning and provide quantitative evidence to guide the decision-making of mosquito control authorities.

Unveiling the role of mosquito and human diel activity patterns in the risk of mosquito-borne disease infection

“…This highlights that mosquito diel activity patterns have a strong impact on the entomological outcome of adulticide spraying. Additionally, the likelihood and magnitude of outbreak occurrences were shown to substantially diminish by when interventions align with peak mosquito activity periods [25]. The findings presented in this study can further our understanding of the effectiveness of alternative public health interventions including educational campaigns on the hours of the day with highest exposure to mosquito vector species.…”