Rhipicephalus (Boophilus) microplus (Canestrini, 1888) e Dermacentor (Anocentor) nitens Neumann, 1897: diversidade genética e potencial de transmissão de patógenos em diferentes biomas do Brasil

Abstract

Ticks are hematophagous arthropods with medical-veterinary importance, since they have capacity to transmit a great pathogens diversity to vertebrate animals, including humans. Each member of the host-vector-pathogen system is affected by the others, this combined effect can influence ticks genetic variation and these genetic differences among tick populations may have important implications regarding the ability of pathogens transmission to hosts. As the main ectoparasites that affect bovine and equine production in Brazil are, respectively, Rhipicephalus microplus and Dermacentor nitens, and also as little is known about the participation of these ticks in the enzootic and epidemic cycles of the bioagents they transmit, these species are the focus of this thesis. Genetic diversity in populations of these tick species and their infection by pathogens were analyzed, in specimens collected between 2011 and 2019, in vertebrate hosts and free in the environment, in areas of investigation focus, environmental surveillance and silent outbreaks of Spotted Fever (SF), from different biomes in Brazil. Low genetic diversity and no defined population structure for R. microplus and D. nitens were observed. Horse-ear-tick specimens were obtained naturally infected with Candidatus Rickettsia andeanae, Rickettsia rhipicephali, Rickettsia felis and Babesia caballi. On the other hand, the cattle-tick specimens were obtained naturally infected with Rickettsia rickettsii, Rickettsia parkeri, R. felis, Rickettsia tamurae, R. rhipicephali, Rickettsia bellii, Ehrlichia minasensis, Ehrlichia canis and Theileria equi, indicating their potential performance in the transmission of Ehrlichia and Theileria to animals in the country and suggesting R. microplus as a marker of Rickettsiae presence or circulation. The obtained results and the diversity of Rickettsiae species in ticks of animals close to humans contribute to the understanding of the enzootic cycle in SF focus areas in Brazil.