Departamento de Medicina Veterinária Preventiva e Saúde animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, Brazil.
Departamento de Medicina Veterinária Preventiva e Saúde animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, Brazil.
Ticks Tick Borne Dis. 2021 May;12(3):101648. doi: 10.1016/j.ttbdis.2021.101648. Epub 2021 Jan 7.
This study evaluated ticks and rickettsial exposure in 220 free-ranging lowland tapirs, Tapirus terrestris, from 2006 to 2018 in selected areas of three major biomes of Brazil - Atlantic Forest, Pantanal, and Cerrado. Overall, a total of 5970 tick specimens representing the following nine species were collected from tapirs: Amblyomma brasiliense, Amblyomma coelebs, Amblyomma dubitatum, Amblyomma ovale, Amblyomma parvum, Amblyomma sculptum, Amblyomma triste, Haemaphysalis juxtakochi, and Rhipicephalus microplus. Amblyomma sculptum was the most prevalent and abundant tick species in all three biomes; however, mean intensity values for A. sculptum were significantly lower in Atlantic Forest than in the Pantanal or Cerrado, and at the same time, statistically similar among tapirs from Pantanal and Cerrado. Contrastingly, mean intensity values for A. coelebs were significantly higher in the Atlantic Forest than in the other biomes. The remaining tick species were collected in lower numbers, or were exclusive for one biome, e.g., A. brasiliense and H. juxtakochi only in the Atlantic Forest. A total of 177 blood sera (123 individuals plus 54 recaptures) were collected from tapirs and tested for the presence of reactive antibodies to six Rickettsia species by immunofluorescence assay. Overall, 69% (9/13), 49% (62/126), and 66% (25/38) tapir sera from Atlantic Forest, Pantanal and Cerrado, respectively, were seroreactive to at least one Rickettsia species, with no significant difference between the three areas. Although many tapir sera reacted simultaneously to ≥2 Rickettsia species, Rickettsia parkeri elicited highest % seroprevalence and endpoint titers, and was incriminated as the possible agent involved in a homologous reaction in tapirs from the three biomes, where A. ovale was previously found infected by R. parkeri. In fact, seroconversion to R. parkeri was demonstrated in five tapirs that were captured at least twice during the study. This study demonstrated that tapirs were found to be constantly infested by several tick species in the Atlantic Forest, Pantanal and Cerrado biomes; however, the richness of tick infestations was concordant to the tick species known to be established in each biome. Under natural conditions, lowland tapirs were shown to be exposed to tick-borne spotted fever group rickettsiae.
本研究评估了 2006 年至 2018 年间，在巴西三个主要生物群落（大西洋森林、潘塔纳尔和塞拉多）的选定地区，220 头自由放养的低地貘（Tapirus terrestris）身上的蜱和立克次体暴露情况。总的来说，从貘身上共采集到 5970 只蜱，代表了以下 9 个种：巴西钝缘蜱（Amblyomma brasiliense）、库氏钝缘蜱（Amblyomma coelebs）、安氏钝缘蜱（Amblyomma dubitatum）、卵圆钝缘蜱（Amblyomma oval）、小钝缘蜱（Amblyomma parvum）、雕刻钝缘蜱（Amblyomma sculptum）、忧郁钝缘蜱（Amblyomma triste）、中突革蜱（Haemaphysalis juxtakochi）和微小牛蜱（Rhipicephalus microplus）。在所有三个生物群落中，雕刻钝缘蜱都是最普遍和丰富的蜱种；然而，在大西洋森林中，A. sculptum 的平均强度值明显低于潘塔纳尔或塞拉多，同时在潘塔纳尔和塞拉多的貘中也没有统计学差异。相比之下，A. coelebs 的平均强度值在大西洋森林中明显高于其他生物群落。其他蜱种的采集数量较少，或仅存在于一个生物群落中，例如 A. brasiliense 和 H. juxtakochi 仅在大西洋森林中采集到。从貘身上共采集了 177 份血清（123 份个体血清加 54 份再捕获血清），并通过免疫荧光检测法检测了这些血清中存在针对六种立克次体的反应性抗体。总的来说，来自大西洋森林、潘塔纳尔和塞拉多的 38%（9/13）、49%（62/126）和 66%（25/38）的貘血清分别对至少一种立克次体呈血清反应性，这三个地区之间没有显著差异。尽管许多貘血清同时对≥2 种立克次体产生反应，但帕克立克次体的血清阳性率和终点滴度最高，被认为是三个生物群落中貘发生同源反应的可能病原体，而在这些生物群落中，此前曾发现卵圆钝缘蜱感染了帕克立克次体。事实上，在研究期间至少两次捕获的 5 头貘中，证明了它们对抗帕克立克次体的血清转化。本研究表明，在大西洋森林、潘塔纳尔和塞拉多生物群落中，低地貘不断受到几种蜱的侵袭；然而，蜱的侵袭丰富度与每个生物群落中已知的已建立的蜱种一致。在自然条件下，低地貘被证明易感染蜱传斑点热群立克次体。
