P29 - Acceptability and Effectiveness of Home Screens to Reduce Aedes aegypti Abundance and Perception of Mosquito Bites in Southern Puerto Rico

Abstract: Puerto Rico remains endemic for dengue, with Aedes aegypti as the primary vector. Given repeated dengue epidemics and high insecticide resistance, sustainable strategies to reduce mosquito-human contact are essential. Puerto Rico Vector Control Unit (PRVCU), with a multi-agency collaboration, implemented the “Si Screens” project to evaluate the acceptability and effectiveness of installing window and door screens in reducing indoor Ae. aegypti abundance and mosquito bite perception among residents.

A total of 500 households from the COPA cohort were enrolled from August 2023 to April 2025, with 250 randomly assigned to receive new or replacement screens on all windows and doors lacking intact screens (intervention) and 250 serving as controls. Entomological assessments were conducted through 15-minute indoor mosquito aspirations at baseline, 6, and 12 months, alongside household questionnaires addressing acceptability, screen condition, and perceived mosquito bites.

At 12 months, intervention homes were significantly less likely to have ≥1 female Ae. aegypti indoors (16%) compared to control homes (31%) and exhibited a lower mean female density (0.29 vs. 0.84 per home). Participants in intervention homes reported a marked reduction in perceived mosquito bites (64% to 29%) compared to control homes (59% to 48%). Overall, 91% of participants expressed satisfaction or high satisfaction with the intervention, citing improved comfort and home aesthetics.

Results indicate that large-scale screen installation is both acceptable and effective in reducing indoor mosquito abundance and perceived biting. However, durability and repair needs are critical considerations for long-term sustainability. Updated data will be presented.