Ovitrap-based monitoring and infestation analysis of Aedes aegypti in Brazil

Abstract

Aedes aegypti has been the primary vector of dengue transmission since the 17th century. This study aimed to analyze the infestation index of Ae. aegypti in the municipality of Itaquiraí, Mato Grosso do Sul, Brazil, using ovitrap-based monitoring. Weekly ovitrap collections were conducted in five urban neighborhoods from March 2015 to December 2018. Two key entomological indicators were analyzed: the Egg Density Index (EDI) and the Ovitrap Positivity Index (OPI). A total of 62,198 Ae. aegypti eggs were collected, with 29.7% of traps testing positive. The overall EDI was 35.2%, peaking in April (48.8%). The highest annual EDI was recorded in 2015 (55.3%). Annual OPI values were 75.9% in 2015, 24.4% in 2016, 15.4% in 2017, and 16.2% in 2018. Monthly OPI peaks occurred in April (2015), February (2016), and January (2017 and 2018). The Poisson distribution (λ = 4.50) suggested a mean of 4.5 eggs per trap per sampling period. The Negative Binomial distribution (r = 0.36, p = 0.07) indicated an aggregated dispersion pattern. The Log-Normal distribution parameters (shape = 1.32, location = 18.00, scale = 0.00) revealed that a small proportion of traps accounted for high egg densities.

The study concludes that oviposition varied substantially across the monitoring period and was spatially clustered. The period of highest transmission risk occurred from January to April. Environmental and climatic factors, alongside consistent control and monitoring actions, are critical for reducing vector populations. Entomological surveillance using ovitraps, combined with community awareness campaigns, constitutes an essential strategy for guiding preventive and vector control measures.

KEY WORDS: Surveillance; insect traps; mosquitoes; arboviruses, dengue.