A cross-sectional study investigating the relationship between environmental sanitation conditions, household practices and Ae. aegypti infestation in disadvantaged communities of Salvador, Brazil

Abstract

Background: Disadvantaged communities characterised by poor sanitation conditions, overcrowding and a lack of vector control management are highly susceptible to Ae. aegypti proliferation and arboviral disease transmission. Effective mosquito control strategies require a detailed understanding of Ae.aegypti oviposition preferences and spatial distribution within these urban environments. This study aimed to identify and characterise potential breeding sites for Ae. aegypti at a fine scale and to examine spatial patterns in mosquito density within disadvantaged communities of Salvador, Brazil.

Methods: An entomological survey was conducted in 174 households, and a socio-demographic and environmental visual inspection survey was performed in 119 households across the study area between May and August 2023. The entomological survey utilised ovitraps to collect samples of Ae. aegypti mosquito eggs and immatures, providing a detailed assessment of mosquito presence and abundance. Concurrently, the visual inspection survey identified potential breeding sites (sources of standing water) for Ae. aegypti in the peri-domestic environment of households. To further explore the relationship between mosquito density and environmental factors, a landcover classification was performed, providing insights into vegetation coverage and other landscape feature in the study area. A multivariate model was fit to identify associations between environmental, household, and socio-demographic factors and Ae. aegypti density.

Results: Of the recovered intradomicile ovitraps, 85 (55.6%) were positive for the presence of eggs while 123 (82.0%) of peridomicile ovitraps were positive for the presence of eggs. A total of 11,211 Ae. aegypti eggs were counted within the study area. The environmental factors strongly associated with Ae. aegypti egg abundance included ovitrap location, depositing garbage in front of the house, living in close proximity (within 10 m) of an open sewer, and the presence of open plastic containers in the peri-domestic environment. However, no significant spatial pattern in mosquito egg density was observed across the study sites.

Date of Award	18 Mar 2025
Original language	English
Awarding Institution	University of Bristol
Supervisor	Guy Howard (Supervisor) & Zoe D Ward (Supervisor)