Association between dengue incidence, rainfall and larval density of Aedes aegypti, in the State of Goiás

Abstract

Introduction: The larval density of Aedes aegypti fluctuates according to seasonal climatic changes. It rises in seasons with higher rainfall, according to the number of potential breeding sites available, thereby predisposing towards increased incidence of dengue. This study aimed to show the association between dengue cases, rainfall and the building infestation rate. Methods: The municipalities were stratified according to the risk and transmission of dengue, and according to presence or absence of mosquito infestation. We used the building larval infestation rate as an indicator for the risk of transmission. Results: There was a positive correlation between the building infestation rate, number of dengue cases and rainfall. Disease transmission was greater during the first four months of each year studied (period of high rainfall) and lower between June and September (season with low rainfall). Dengue cases occurred continually and in increased numbers between January and March of each year, and then declined in the months of April and May, when it ceased in most municipalities. The metropolitan region of Goiânia was responsible for more than 80% of the dengue cases in Goiás. Transmission was continuous throughout the year, although lower during the period from May to December. Over the last three months, there was increased transmission, but usually still at low rates. Conclusions: The positive correlation between the building infestation rate and rainfall, and between this rate and the incidence of cases, indicated a significant association between increasing transmission and increasing numbers of dengue cases.