Infecção de flebotomíneos por Leishmania infantum em áreas endêmicas para leishmaniose visceral e suas principais fontes de alimentação

Abstract

The visceral leishmaniasis (VL) is a tropical disease that remains a public health problem in many countries located in tropical and subtropical areas around the world. In Brazil, the infection rate of Leishmania infantum, the etiological agent of VL, is higher in focal areas, including the state of Rio Grande do Norte. The transmission cycle is anthropozoonotic, with the dog being considered the main reservoir and feed for the hematophagous female sandflies, especially for the species of opportunistic character Lutzomyia longipalpis, which is the most important epidemiological vector. The objective of this study is to determine the vectorial infection rate of Leishmania infantum and the main feed source of sandflies in the regions of Nordelândia, África and São Gonçalo do Amarante, which are endemic areas of VL in RN. For this purpose, weekly collections were made between September 2020 and September 2022, using CDC (Center for Disease Control) traps in the peridomicile of 22 houses that agreed to participate. A total of 2494 sandflies were collected, 83.8% (n=2090) being males and 16.2% (n=404) females. In África and Nordelândia, which are urban areas, there were higher numbers of total sandflies and female sandflies captured between April and May, which is the rainy season, while in Nova Zelândia, a rural area of São Gonçalo do Amarante, this peak was in October, the dryer season. Among the 404 female sandflies captured, after the dosage and analysis of purity by Nanodrop and testing for the presence of DNA of L. longipalpis, 64.3% (n=260) had non-degraded DNA and were able to perform qPCR to detect the infection of L. infantum and feed source, while 35.7% (n=144) were degraded samples or not L. longipalpis and were discarded. qPCR detected 16.2% (n=42) positivity for L. infantum, being most present in São Gonçalo 83.3% (n=35), followed by Nordelândia 12% (n=5) and África with 4.7% (n=2). The main feed sources were tested by qPCR: dog, human, chicken, cat and horse, with meals occurring in all of them. The highest incidence was in chicken 11.7% (n=43) and then human 4.1%. Furthermore, there was mixed feeding in human/chicken 0.8% (n=3), cat/chicken 0.3% (n=1) and dog/chicken 0.3% (n=1). Among the 42 positive females for L. infantum, 4 had feed from a dog and 3 from chicken. The presence of feeding infected L. longipalpis females in domestic animals and humans suggests the occurrence of endemic symptomatic and asymptomatic VL in RN and the need to study the dynamics and habits of these vectors.