Are vacant lots within urban blocks a risk factor for Aedes aegypti higher occurrence and density on neighbouring properties?

The present study aimed to evaluate the potential relationship between the presence of vacant lots and the occurrence of Aedes aegypti (Diptera: Culicidae) mosquitoes in adjacent occupied properties. For that, we used entomological traps and georeferencing tools. The use of entomological traps, for example, Adultrap and ovitrap, is among the main strategies for the identification and monitoring of Ae. aegypti populations and its hotspots, often combined with geographic monitoring systems. A total of 225 ovitraps and 225 Adultraps, corresponding to 25 traps of each type per sentinel geographic unit (UGS), were inspected during each weekly sampling round, across nine defined areas, known as UGSs, in the Brazilian triple-border municipality of Foz do Iguaçu during a dengue epidemic period. The results were used to calculate the Adultrap Positivity Index (API) and Adult Density Index (ADI), as well as the Ovitrap Positivity Index (OPI) and the Egg Density Index (EDI). Vacant lots were identified through satellite images, and the results were calculated using Generalized Linear Mixed Model. Trap readings were aggregated across 143 urban blocks. Our statistical analysis detected no statistically significant association between block-level vacant-lot coverage and any of the evaluated entomological indices. For API, a 10-percentage-point increase in vacant-lot coverage corresponded to an estimated 5.7% reduction in positive Adultrap readings (expected-count ratio = 0.943; 95% confidence interval [CI]: 0.880-1.011; p = 0.101), although the CI was compatible with effects ranging from a 12.0% reduction to a 1.1% increase.