Caatinga is a biome exclusive to the semiarid zone of Brazil, where studies on ticks and tick-borne diseases are scarce. Herein, we investigated the occurrence of Rickettsia, Ehrlichia, and Coxiella in wild mammals, domestic dogs and their ectoparasites using molecular and serological techniques. During 2014–2016, blood samples and ectoparasites were collected from 70 small mammals (51 rodents, 18 marsupials, 1 wild canid) and 147 domestic dogs in three areas of the Caatinga. Through serological analyses of domestic dogs of the three areas, 8 to 11 % were seropositive for Rickettsia rickettsii, 9 to 37 % for Rickettsia amblyommatis, 61 to 75 % for Ehrlichia canis, and 0–5% for Coxiella burnetii. All wild mammals were seronegative for Rickettsia spp. and C. burnetii, except for one rodent (Wiedomys pyrrhorhinos) and one marsupial (Didelphis albiventris) that were seroreactive to C. burnetii, one wild canid (Cerdocyon thous) for R. amblyommatis, and two Rattus rattus for Rickettsia spp. Through PCR targeting DNA of Rickettsia, Ehrlichia or Coxiella, all blood samples were negative, except for the presence of Ehrlichia canis DNA in 8.8 % of the domestic dogs, and a recently reported novel agent, Ehrlichia sp. strain Natal, in one marsupial (Gracilinanus agilis). A total of 222 ticks, 84 fleas, and six lice were collected. Ticks were mostly Rhipicephalus sanguineus sensu lato, some Ixodes loricatus, Ornithodoros rietcorreai, Haemaphysalis sp., and Amblyomma spp.; fleas were Ctenocephalides felis felis, Pulex sp. and Polygenis (Polygenis) bohlsi jordani; and lice were Polyplax sp. and Gyropus sp. Through molecular detection of microorganisms, 9% of C. felis felis contained Rickettsia felis, 20 % of A. auricularium contained R. amblyommatis and 13 % of A. parvum contained ‘Candidatus Rickettsia andeanae’, whereas Ehrlichia canis DNA was detected in at least 6% of the R. sanguineus s.l. from one area. We report a variety of ectoparasites infesting small mammals and domestic dogs in the Caatinga biome, where these ectoparasites probably act as vectors of rickettsiae, ehrlichial agents (E. canis and Ehrlichia sp. strain Natal) and C. burnetii. Our results highlight to the potential risks of human infection by these tick-borne agents in the Caatinga biome.

卡廷加是巴西半干旱地区特有的生物群落，那里对蜱虫和蜱传疾病的研究很少。在此，我们利用分子和血清学技术研究了立克次体、埃利希体和柯克斯体在野生哺乳动物、家犬及其体外寄生虫中的发生情况。 2014 年至 2016 年期间，从卡廷加三个地区的 70 只小型哺乳动物（51 只啮齿动物、18 只有袋动物、1 只野生犬科动物）和 147 只家犬采集了血液样本和体外寄生虫。对三地家犬进行血清学分析，立克次体血清阳性率为8%～11% ，弱立克次体血清阳性率为9%～37%，犬埃利希体阳性率为61%～75%，伯内氏柯克斯体血清阳性率为0%～5%。所有野生哺乳动物的立克次体血清呈阴性。和伯内特立克次体，除了一种啮齿类动物（ Wiedomyspyrrhorhinos ）和一种有袋动物（ Didelphis albiventris ）对伯内特氏体有血清反应，一种野生犬科动物（ Cerdocyonthous ）对R.amblyommatis有血清反应，两种鼠类对立克次体有血清反应。通过针对立克次体、埃利希体或柯克斯体DNA 的 PCR，除了 8.8% 的家犬中存在犬埃利希体DNA 以及最近报道的新病原体埃利希体sp. 之外，所有血液样本均为阴性。一种有袋动物 ( Gracilinanus agilis ) 中的 Natal 菌株。总共收集了 222 只蜱虫、84 只跳蚤和 6 只虱子。 蜱类主要为Rhipicephalus sanguineus sensu lato、部分蜱虫、 Ornithodoros rietcorreai 、 Haemaphysalis sp.和Amblyomma spp.；跳蚤有Ctenocephalides felis felis 、 Pulex sp.。和Polygenis ( Polygenis ) bohlsi jordani ；和虱子是Polyplax sp。和Gyropus sp。通过微生物分子检测，9%的猫C. felis含有猫立克次体， 20%的A. aurillaryium含有R. amblyommatis ，13%的A. parvum含有‘ Candidatus Rickettsia andeanae’，而至少在犬埃利希体DNA中检测到。 6% 的R. sanguineus sl 来自一个地区。我们报告了卡廷加生物群落中感染小型哺乳动物和家犬的多种体外寄生虫，这些体外寄生虫可能是立克次体、埃里希体病原体（犬埃里希体和纳塔尔埃里希体菌株）和伯内特立克次体的载体。我们的结果强调了卡廷加生物群落中这些蜱传病原体感染人类的​​潜在风险。