Setor de Patologia Veterinária, Departamento de Patologia Clínica Veterinária, Faculdade de Veterinária (FAVET), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil.
State Foundation of Livestock Research, Eldorado do Sul 92990-000, Brazil.
Ticks Tick Borne Dis. 2021 Sep;12(5):101731. doi: 10.1016/j.ttbdis.2021.101731. Epub 2021 May 2.
Rangeliosis is a condition transmitted by the tick Amblyomma aureolatum and caused by the protozoan parasite Rangelia vitalii in canids. In domestic dogs, the disease causes a severe hemolytic disease, while in wild canids the piroplasm is often detected without any clinical abnormality. This study aimed to detect and quantify the number of copies of the R. vitalii Hsp70 gene (indirect parasite burden) in several organs of domestic and South American wild canids (Cerdocyon thous and Lycalopex gymnocercus) to elucidate distinct clinical presentations of rangeliosis in these species. A total of seven domestic dogs that died due to rangeliosis and 38 wild foxes were initially included, with all dogs presenting histological and molecular features of rangeliosis, while eight C. thous were positive at the molecular analysis for R. vitalii. Fragments of 22 organs collected from domestic (n = 7) and wild foxes (n = 8) were employed for histological and molecular quantification using real-time polymerase chain reaction aiming at the Hsp70 gene. Histologically, parasitophorous vacuoles were constantly detected in the dogs, while these were detected only in two C. thous. Parasitic burden was significantly higher in the digestive, cardiorespiratory, endocrine, genitourinary, and skeletal-muscle systems of domestic dogs when compared to wild foxes. In the hematopoietic system of wild canids, some organs, such as the lymph nodes and tonsils, presented significantly lower amounts of R. vitalii, while other organs (spleen, bone marrow, and blood) had results similar to those of domestic dogs. Additionally, the central nervous system of both domestic and wild canids presented a similar quantity of R. vitalii. The etiological agent is possibly maintained through an asexual reproductive process (merogony) in both domestic and wild species. Nonetheless, a limited or short-duration schizogony phase occurs in C. thous, which would designate this species as a possible reservoir host for the agent. Dogs, in contrast, would most likely act as accidental hosts, presenting a severe and more pathogenic schizogony phase, resulting in characteristic clinical and pathological rangeliosis.
冈比亚锥虫病是一种由肩突硬蜱传播的疾病，由原生动物寄生虫兰格尔利亚 vitalii 引起，发生于犬科动物。在犬科动物中，该疾病会导致严重的溶血性疾病，而在野生犬科动物中，通常可以检测到锥虫，但没有任何临床异常。本研究旨在检测和量化几种家养和南美野生犬科动物（鬃狼和鬃狼）器官中兰格尔利亚 vitalii Hsp70 基因的拷贝数（间接寄生虫负担），以阐明这些物种中冈比亚锥虫病的不同临床表现。总共纳入了 7 只因冈比亚锥虫病而死亡的家养犬和 38 只野生狐狸，所有犬均呈现出冈比亚锥虫病的组织学和分子特征，而 8 只鬃狼在分子分析中对兰格尔利亚 vitalii 呈阳性。从家养犬（n=7）和野生狐狸（n=8）中采集的 22 种器官的组织碎片，用于组织学和实时聚合酶链反应（PCR）分子定量，目的是检测 Hsp70 基因。组织学上，在犬中始终检测到寄生泡，而在鬃狼中仅检测到 2 只。与野生狐狸相比，家养犬的消化、心肺、内分泌、泌尿生殖和骨骼肌肉系统的寄生虫负担明显更高。在野生犬科动物的造血系统中，一些器官（如淋巴结和扁桃体）的兰格尔利亚 vitalii 含量明显较低，而其他器官（脾、骨髓和血液）的结果与家养犬相似。此外，家养和野生犬科动物的中枢神经系统具有相似数量的兰格尔利亚 vitalii。病原体可能通过家养和野生物种的无性生殖过程（裂殖生殖）得以维持。然而，在鬃狼中发生了有限或短暂的裂殖生殖阶段，这将使该物种成为病原体的可能储存宿主。相比之下，犬科动物很可能是偶然宿主，呈现出严重且更具致病性的裂殖生殖阶段，导致特征性的临床和病理学冈比亚锥虫病。
