MONITORAMENTO DE FLEBOTOMÍNEOS (DIPTERA: PSYCHODIDAE), PRÉ E PÓS ENCOLEIRAMENTO CANINO EM ÁREAS ENDÊMICAS DE LEISHMANIOSE VISCERAL, BRASIL

Abstract

ABSTRACT

Leishmaniases are diseases caused by protozoa of the genus Leishmania, which manifest in three clinical forms. The most severe form of the disease is visceral leishmaniasis (VL). The protozoan Leishmania (Leishmania) infantum is the causative agent of VL, with infection occurring mainly through the bite of female sandflies of Lutzomyia longipalpis and/or Lu. cruzi in Brazil. This study aimed to carry out entomological monitoring of sandfly fauna, evaluating its composition before and after the use of collars impregnated with deltamethrin on dogs, in urban areas of three municipalities endemic for visceral leishmaniasis (VL) in Brazil: Campo Grande (MS), São Luís (MA) and Caxias (MA). According to the Ministry of Health, these cities are classified as intense, very intense, and high VL transmission areas, respectively. Furthermore, we sought to detect natural infection by Leishmania and investigate the eating habits of sandflies through molecular analyses. Monthly collections were carried out during three consecutive nights, with CDC-type light traps at 20 points in each municipality. The traps were installed at 4:00 p.m. and removed at 7:00 a.m., inside and outside the home.The sandflies were screened, assembled, and identified according to Galati (2023). In Campo Grande, captures took place between July 2021 and August 2023. At the time, 8,984 specimens were identified (6,199 males and 2,785 females) with 63.9% collected indoors and 36.1% outside the home, with Lu. longipalpis, the most abundant species (99.59%). Collaring in this city began in August 2022. In São Luís (MA), collections took place between August 2021 and August 2023. With respect to this city, 4,522 insects were captured (3,230 males and 1,292 females), with 14.7% collected indoors and 85.3% outside the home. Lu. longipalpis was the dominant species (98.14%). The collection period in Caxias (MA) took place between August 2021 and June 2023, where 119,978 specimens were captured (85,055 males and 34,923 females), with 7.02% indoors and 92.98% outside the home. The percentage of Lu. longipalpis accounted for 45.9% of the total species collected in this municipality. The dogs were collared in February 2022 in both Caxias and São Luís. Other medically important species were also recorded: Nyssomyia whitmani (the most abundant species in Caxias) and Bichromomyia flaviscutellata, both vectors of the causative agents of cutaneous leishmaniasis. The use of collars impregnated with 4% deltamethrin on dogs proved to be an effective tool in reducing the sandfly fauna. The results of this study demonstrated an immediate impact following the intervention, with a sharp and significant decline in the population dynamics of Lutzomyia longipalpis — a key finding for the implementation of entomological control strategies and reduction of disease cases. Lutzomyia longipalpis females carrying Leishmania DNA were detected both before and after the intervention, indicating that parasite circulation persists, even at lower levels. This suggests that the use of insecticide-impregnated collars should be combined with other environmental management measures to effectively control leishmaniasis.

Keywords: Sandfly. Visceral Leishmaniasis. Deltamethrin. Vector control.