PDF(Pubmed)
Abstract：
Amblyomma ticks are vectors of both Rickettsia rickettsii and R. parkeri in the Americas, where capybaras (Hydrochoerus hydrochaeris) are the main hosts in urban areas, thus contributing to the transmission of spotted fever. Herein, we studied: (i) the seasonal dynamics and abundance of ticks in areas where capybaras live, (ii) the effect of environmental variables on tick abundance, and (iii) the presence of Rickettsia-infected ticks. Between September 2021 and September 2022, we sampled ticks using cloth-dragging at 194 sites on the shore of Lake Paranoá in Brasília, Brazil. We measured environmental data (season, vegetation type, canopy density, temperature, humidity, and presence or vestige of capybara) at each site. Nymphs and adults were morphologically identified to the species level, and a selected tick sample including larvae was subjected to genotypic identification. We investigated Rickettsia-infected ticks by PCR (gltA, htrA, ompB, and ompA genes) and associations between tick abundance and environmental variables using Generalized Linear Models. A total of 30,334 ticks (96% larvae) were captured. Ticks were identified as Amblyomma, with A. sculptum comprising 97% of the adult/nymphs. Genotype identification of a larval sample confirmed that 95% belonged to A. dubitatum. Seasonal variables showed significant effects on tick abundance. Most larvae and nymphs were captured during the early dry season, while the adults were more abundant during the wet season. Vegetation variables and the presence of capybaras showed no association with tick abundance. Rickettsia parkeri group and R. bellii were identified in A. dubitatum, while A. sculptum presented R. bellii. We conclude that: (i) Amblyomma ticks are widely distributed in Lake Paranoá throughout the year, especially larvae at the dry season, (ii) the abundance of Amblyomma ticks is explained more by climatic factors than by vegetation or presence of capybaras, and (iii) A. dubitatum ticks are potential vectors of R. parkeri in Brasília.
摘要：
Amblyomma是美洲立克次体立克次体和R.parkeri的载体，在城市地区，水牛（Hydrochoerushydrochaeris）是主要宿主，从而导致斑点热的传播。在这里，我们研究了:(一)水鱼生活地区蜱的季节动态和丰度，(Ii)环境变量对蜱丰度的影响，和(iii)立克次体感染的蜱的存在。在2021年9月至2022年9月之间，我们在巴西利亚的Paranoa湖岸边的194个地点使用拖布法采样了蜱，巴西。我们测量了环境数据(季节，植被类型,树冠密度,温度,湿度,湿度以及水豚的存在或痕迹）在每个站点。若虫和成虫在形态上被鉴定为物种水平，并对包括幼虫在内的选定蜱样品进行基因型鉴定。我们通过PCR研究了立克次体感染的蜱(gltA，HTRA,ompB,和ompA基因)以及使用广义线性模型的蜱丰度和环境变量之间的关联。总共捕获了30,334只蜱(96%的幼虫)。蜱被鉴定为弱视，雕塑占成年/若虫的97％。幼虫样品的基因型鉴定证实95％属于A.dubitatum。季节变量对蜱丰度有显著影响。大多数幼虫和若虫是在旱季早期捕获的，而成年人在雨季更丰富。植被变量和卷心菜的存在与tick虫的丰度无关。立克次体parkeri组和R.bellii在杜比图坦杆菌中被发现，而A.雕塑展示了R.bellii。我们得出的结论是：（i）全年在巴拉诺阿湖广泛分布，尤其是旱季的幼虫，（ii）Amblyomma蜱的丰度更多地通过气候因素来解释，而不是通过植被或水蛭的存在来解释，和（iii）A.dubitatumtick是巴西利亚的R.parkeri的潜在向量。
