Entomological investigation after an outbreak of dengue at the riverside of Rio Doce, Espírito Santo State, Brazil

Abstract

Background In 2019, a dengue outbreak involving Aedes albopictus occurred in a rural area of Espírito Santo, Brazil, motivating our study in Sooretama and Linhares. Methods We set traps to sample immature mosquito larvae at 40 sites, with weekly inspections from July 2022 to January 2023. Adult specimens were collected monthly at 19 sites, each collection lasting 15 min. The collections were performed during daylight using a Castro vacuum device, a small electric vacuum suction device, a net capture device and insect cages. We conducted molecular analyses of adult Aedes to identify arbovirus infection. Results Among 20 217 immature forms, we identified Aedes aegypti (n=16 340), Aedes albopictus (n=3403), Culex quinquefasciatus (n=426) and Limatus durhami Theobald 1901 (n=48). Of the 3026 adult specimens, there were C. quinquefasciatus (n=2857), A. aegypti (n=141) and A. albopictus (n=28). Each site had an average of 159 adult specimens, 16 per house. Among the 159 specimens, 150 were C. quinquefasciatus. The average frequency of adult A. aegypti per house was 1.2 (0.08 per minute of collection). Adult Aedes were not infected. Conclusions Entomological surveillance should consider A. albopictus and A. aegypti in rural areas, providing proper vector control strategies to prevent the spread of arboviruses.