Microbiota de carrapatos de importância em saúde humana e veterinária no estado do Rio Grande do Sul

• Ano de defesa: 2019
• Autor(a) principal: Dall'Agnol, Bruno
• Orientador(a): Ferreira, Carlos Alexandre Sanchez
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Pontifícia Universidade Católica do Rio Grande do Sul
• Programa de Pós-Graduação: Programa de Pós-Graduação em Biologia Celular e Molecular
• Departamento: Escola de Ciências
• País: Brasil
• Palavras-chave em Português: Amblyomma Aureolatum; Ornithodoros Brasiliensis; Coxiella; Francisella; Rickettsia; Bacterioma; Doenças Transmitidas Por Carrapatos
• Área do conhecimento CNPq: CIENCIAS BIOLOGICAS::BIOLOGIA GERAL
• Link de acesso: http://tede2.pucrs.br/tede2/handle/tede/9074

Ticks are arthropods ectoparasites that feed on vertebrate bloods causing damage to the health of their hosts by direct damage caused by blood spoliation, while facilitating the occurrence of myiasis and secondary bacterial infections. However, the most important problem associated with tick infestation is the ability to transmit pathogens such as viruses, bacteria, protozoa and nematodes. Among the species of ticks present in the state of Rio Grande do Sul (RS) with importance for human and veterinary health are the species Amblyomma aureolatum and Ornithodoros brasiliensis. The species A. aureolatum belongs to the Ixodidae family and its natural hosts are wild birds and rodents in the immature stages and wild carnivores in the adult form, and can also parasitize domestic animals and humans. The tick A. aureolatum is the main vector of Rickettsia rickettsii in the metropolitan region of São Paulo state in the Atlantic Rainforest biome and was also found infected by Rickettsia parkeri strain Atlantic Rainforest in the same biome. It is also vector of a protozoan pathogenic for dogs, Rangelia vitalii. The tick O. brasiliensis belongs to the Argasidae family and until then there are only records of this species in the region known as Campos de Cima da Serra in the RS state. The hosts parasitized by this species of tick may suffer from a toxicose caused by components of the parasite's saliva. There are also reports of the presence of bacteria of the genus Borrelia present in this tick. In addition to pathogenic bacteria, as in other metazoans, there is an interaction of ticks with other microorganisms and this relationship brings mutual benefits to the species involved. Therefore, the objectives of the study were i) to characterize the bacteriome of A. aureolatum and O. brasiliensis; ii) to characterize the parasitism and increase the known distribution of O. brasiliensis; and iii) to investigate pathogenic bacteria of the genus Rickettsia in ticks and wild carnivorous hosts. In A. aureolatum, the predominant bacterial phyla were Proteobacteria (98.68%), Tenericutes (0.70%), Bacteroidetes (0.14%), Actinobacteria (0.13%) and Acidobacteria (0.05%). The predominant genera were Francisella (97.01%), Spiroplasma (0.70%), Wolbachia (0.51%), Candidatus Midichloria (0.25%) and Alkanindiges (0.13%). The predominant phyla in O. brasiliensis were Proteobacteria (90.27%), Actinobacteria (7.38%), Firmicutes (0.77%), Bacteroidetes (0.44%) and Planctomycetes (0.22%). The predominant bacterial genera were Coxiella (87.71%), Nocardioides (1.73%), Saccharopolyspora (0.54%), Marmoricola (0.42%) and Staphylococcus (0.40%). Considering the genera with importance in human and animal health that can be transmitted by ticks: (i) Coxiella sp. was found in all stages of O. brasiliensis; (ii) Francisella sp. in all specimens of A. aureolatum and in non-fed nymphs of O. brasiliensis; (iii) Rickettsia sp. in females of A. aureolatum and females and nymphs of O. brasiliensis. With regard to O. brasiliensis, we report here a series of clinical cases associated with O. brasiliensis parasitism in a group of tourists in Caxias do Sul municipality, RS state. These cases call attention to undiagnosed noninfectious syndromes caused by locally restricted ticks. These results amplify the known distribution of O. brasiliensis, besides being the first record of this species in caves. Regarding the research of Rickettsia spp. in wild carnivorous ticks, of the 292 ticks collected, 22 (7.5%) were positive by PCR for the presence of Rickettsia parkeri sensu stricto (s.s) DNA. In addition, 20 (62%) wild canids showed antibodies against R. parkeri. The results suggest that wild canids are involved in the enzootic cycle of R. parkeri s.s. in the Pampa biome and could be responsible for the dispersion of pathogens and their vectors. Finally, the results found here contribute to the understanding of the eco-epidemiology of the relationships between bacteria and ticks of interest in public health in RS State. It is expected that the characterization of the microbiota of these tick species together with the pathogen research in these vectors can help in the prevention of vector-borne diseases in Brazil and to understand the natural history of these parasites.