Fundação Oswaldo Cruz - Fiocruz Rondônia, Porto Velho, RO, 76812-245, Brazil.
Programa de Pós Graduação em Biologia Experimental, Fundação Universidade Federal de Rondônia, Porto Velho, RO, 76801-059, Brazil.
Parasit Vectors. 2020 Aug 17;13(1):422. doi: 10.1186/s13071-020-04295-9.
Almost 1000 cases of American cutaneous leishmaniasis have been registered yearly in Rondônia State, Brazil. Little is known about the Leishmania transmission cycle (vectors and reservoirs) in the state. This study aimed to evaluate sand fly fauna from two vertical stratification layers in order to identify potential vectors and their blood-meal sources.
The study was conducted in Jamari National Forest. Sand flies were collected in the canopy (15 m) and at ground level (1 m) using HP light traps during four months, February, April, August and October, 2018. Insects were identified to the species level, and females were subjected to DNA extraction and PCR targeting minicircle kDNA and hsp70 (for Leishmania detection and species identification), and cytb (to identify blood-meal sources). Exploratory data analysis was used to determine mean of abundance and species richness between stratifications. The hsp70 and cytb sequences were analyzed and compared with sequences from GenBank.
Overall, 68 species were identified from 15,457 individuals. On the Potosi trail, 7531 individuals of 49 species were collected; canopy captures totaled 6463 individuals of 46 species, while ground captures totaled 1068 individuals of 38 species. On the Santa Maria trail, 7926 individuals of 61 species were collected; canopy captures totaled 6136 individuals of 51 species, while ground captures totaled 1790 individuals of 53 species. A total of 23 pools were positive for kDNA (canopy n = 21, ground n = 2). Only two samples were sequenced for hsp70 (both in canopy); one sequence exhibited similarity with Leishmania braziliensis (Lutzomyia davisi pool) and another with L. naiffi (Lu. antunesi pool). The cytb fragment was amplified in 11 of 86 samples. Sample sequencing identified cytb DNA from 5 blood-meal sources: Micrastur gilvicollis, Psophia viridis, Tamandua tetradactyla, Homo sapiens and Choloepus didactylus.
Sand fly fauna is more diverse in the canopy than at ground level. Factors such as blood-meal sources, resting sites, and abiotic components probably contribute to high abundance in the canopy. Our results reinforce the possibility that Lu. antunesi and Lu. davisi participate in Leishmania transmission in forest environments and may play an important role in transmission from sylvatic to human hosts.
巴西朗多尼亚州每年登记的美国皮肤利什曼病病例近 1000 例。关于该州利什曼虫传播周期（媒介和宿主）的了解甚少。本研究旨在评估来自两个垂直分层层的沙蝇区系，以确定潜在的媒介及其血液来源。
该研究在 Jamari 国家森林进行。2018 年 2 月、4 月、8 月和 10 月，使用 HP 光阱在树冠（15 米）和地面（1 米）收集了四个月的沙蝇。对昆虫进行了种级鉴定，雌性昆虫进行了 DNA 提取和针对微环 kDNA 和 hsp70（用于检测利什曼原虫和种鉴定）以及 cytb（用于鉴定血液来源）的 PCR。使用探索性数据分析来确定分层之间丰度和物种丰富度的平均值。对 hsp70 和 cytb 序列进行了分析，并与 GenBank 中的序列进行了比较。
总体而言，从 15457 个人中鉴定出 68 种。在波托西小径上，共采集了 7531 个人的 49 种；树冠捕获量总计 6463 个人的 46 种，而地面捕获量总计 1068 个人的 38 种。在圣玛丽亚小径上，共采集了 7926 个人的 61 种；树冠捕获量总计 6136 个人的 51 种，而地面捕获量总计 1790 个人的 53 种。共有 23 个池对 kDNA 呈阳性（树冠 n=21，地面 n=2）。仅对 2 个 hsp70 样本进行了测序（均在树冠中）；一个序列与利什曼原虫巴西利什曼原虫（Lutzomyia davisi 池）相似，另一个与 L. naiffi（Lu. antunesi 池）相似。cytb 片段在 86 个样本中的 11 个中被扩增。样本测序鉴定出 5 种血液来源的 cytb DNA：Micrastur gilvicollis、Psophia viridis、Tamandua tetradactyla、Homo sapiens 和 Choloepus didactylus。
与地面相比，树冠中的沙蝇区系更加多样化。血液来源、休息地点和非生物成分等因素可能导致树冠中大量存在。我们的结果证实了 Lu. antunesi 和 Lu. davisi 可能参与森林环境中的利什曼虫传播，并可能在从森林宿主到人类宿主的传播中发挥重要作用。
