The relationship between entomological indicators of Aedes aegypti abundance and dengue virus infection

Abstract

Routine entomological monitoring data are used to quantify the abundance of Ae. aegypti. The public health utility of these indicators is based on the assumption that greater mosquito abundance increases the risk of human DENV transmission, and therefore reducing exposure to the vector decreases incidence of infection. Entomological survey data from two longitudinal cohort studies in Iquitos, Peru, linked with 8,153 paired serological samples taken approximately six months apart were analyzed. Indicators of Ae. aegypti density were calculated from cross-sectional and longitudinal entomological data collected over a 12-month period for larval, pupal and adult Ae. aegypti. Log binomial models were used to estimate risk ratios (RR) to measure the association between Ae. aegypti abundance and the six-month risk of DENV seroconversion. RRs estimated using cross-sectional entomological data were compared to RRs estimated using longitudinal data. Higher cross-sectional Ae. aegypti densities were not associated with an increased risk of DENV seroconversion. Use of longitudinal entomological data resulted in RRs ranging from 1.01 (95% CI: 1.01, 1.02) to 1.30 (95% CI: 1.17, 1.46) for adult stage density estimates and RRs ranging from 1.21 (95% CI: 1.07, 1.37) to 1.75 (95% CI: 1.23, 2.5) for categorical immature indices. Ae. aegypti densities calculated from longitudinal entomological data were associated with DENV seroconversion, whereas those measured cross-sectionally were not. Ae. aegypti indicators calculated from cross-sectional surveillance, as is common practice, have limited public health utility in detecting areas or populations at high risk of DENV infection.

Risk Factors Associated with Dengue Transmission and Spatial Distribution of High Seroprevalence in Schoolchildren from the Urban Area of Medellin, Colombia

“…There is no consensus in the literature about the threshold of Ae. aegypti density measures associated with the increased risk of human DENV infection [25, 33]. In our study, only HI was significantly associated with DENV infection.…”

“…DENV infection is a complex, cyclic, and time-varying disease [25]. In the present study, using a representative sample of schoolchildren population from districts of the urban area of Medellin, we combined serologic and sociodemographic data and entomologic and geospatial information to better understand DENV transmission patterns.…”

“…aegypti based on PAHO entomological surveillance guidelines [34]. Several studies claimed that vector densities fail to describe current DENV infection risk [25, 35]. These discrepancies suggest the inadequacy of the current indices in dengue transmission, probably because they were initially developed for the evaluation of yellow fever transmission risk [36].…”

“…These movements determine the introduction of DENV into Ae. aegypti population and the presence of susceptible individuals that mosquitoes infect, perpetuating new rounds of transmission and appearance of outbreaks [25]. Therefore, many gaps are still present in our knowledge model of the relationships between vector density, vector competence, human susceptibility, and severity of DENV infection [35].…”

Cluster-Randomized Test-Negative Design Trials: A Novel and Efficient Method to Assess the Efficacy of Community-Level Dengue Interventions

“…The absence of such trials might reflect the common belief that mosquito population suppression must inevitably lead to lower disease incidence, yet this relationship is poorly characterized and unlikely to be linear (45, 46). Additionally, there is a perception that cluster-randomized trials require fever surveillance of predefined cohorts of “at risk” individuals and that such efforts must always be logistically and financially demanding.…”