Household and community drivers of Aedes aegypti infestation in tropical cities: Guiding community-led interventions

Disadvantaged communities characterised by poor sanitation conditions, overcrowding, and limited vector control are highly susceptible to Aedes aegypti proliferation and arboviral disease transmission. Effective mosquito vector control requires a detailed understanding of Ae. aegypti oviposition preferences and spatial distribution within such urban environments. This study aimed to identify key environmental and behavioural drivers of Ae. aegypti proliferation in disadvantaged communities of Salvador, Brazil, combining household surveys, entomological assessments, and remote sensing to guide targeted public health interventions. Between March and December 2023, using a systematic sampling approach, an entomological survey was conducted in 174 households, alongside a socio-demographic and environmental visual inspection survey in 119 households within two disadvantaged communities of Salvador. Ovitraps were used to collect Ae. aegypti eggs and immatures, providing a detailed assessment of mosquito density. The visual inspection survey identified potential breeding sites (sources of standing water) for Ae. aegypti in the peri-domestic environment. Landcover classification was performed to provide insights into vegetation coverage and other landscape features in the study area. Multivariate modelling explored associations between environmental and household factors, and Ae. aegypti density. Of the 303 recovered ovitraps, 85 (55.6%) indoor and 123 (82.0%) outdoor were positive for eggs, with a total of 11,211 Ae. aegypti eggs recorded. Environmental factors strongly associated with egg abundance included ovitrap location, garbage deposited in front of the house, proximity (within 10 m) to an open sewer, and the presence of open plastic containers in the peri-domestic environment. No significant spatial clustering of mosquito egg density was observed. Breeding was most prolific in the peri-domestic environment, highlighting the importance of keeping these areas clean and well-managed. Improving waste disposal, water storage practices, and sanitation infrastructure could enhance the effectiveness of vector control. These findings provide evidence to inform integrated strategies for reducing arboviral disease risk in disadvantaged urban settings.