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| Author(s): |
Francisco Borges Costa
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD) |
| Defense date: | 2014-05-30 |
| Examining board members: |
Marcelo Bahia Labruna;
Ricardo Augusto Dias;
Rita de Maria Seabra Nogueira de Candanedo Guerra;
Mauricio Claudio Horta;
Adriano Pinter dos Santos
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| Advisor: | Marcelo Bahia Labruna |
| Abstract | |
The emergence and reemergence of diseases transmitted by arthropods are challenges for the Veterinary and Human medicine. Domestic dogs are often exposed to different tick species, what makes these animals good sentinels for rickettsial diseases that affect humans. The state of Maranhão is located in the northeastern region of Brazil, in a transition area from Amazon to Savannah biomes. In this context, the present study aimed to evaluate rickettsial infection in dogs from this state. During the period 2011 to 2013 blood samples were randomly collected from 1560 domestic dogs, being from urban and rural areas of eight municipalities of Maranhão: Açailândia, Balsas, Barreirinhas, Caxias, Cururupu, Grajaú, São Bento and São Domingos. Samples were tested by indirect imunofluorescence assay against 5 Rickettsia species: Rickettsia rickettsii, Rickettsia parkeri, \"Candidatus Rickettsia amblyommii\", Rickettsia rhipicephali and Rickettsia bellii. Ticks were collected on dogs to morphological taxonomic identification and to rickettsia research, almost ticks were submitted to hemolymph test and shell vial attempting to isolate rickettsia. Overall, 12.6% (196/1560) of the dogs were seroreactive to Rickettsia spp. Ninety-two sera showed titers to Rickettsia parkeri, \"Candidatus Rickettsia amblyommii\", Rickettsia rhipicephali and Rickettsia bellii at least 4- fold higher than those observed to the other rickettsial antigens. In this way, we considered that these dogs were infected by Rickettsia parkeri (1sera), \"Candidatus Rickettsia amblyommii\" (73 sera), Rickettsia rhipicephali (6 sera) and Rickettsia bellii (12 sera), with titers ranging from 128 to 16,384. Nine hundred and fifty-nine ticks were collected on dogs (Rhipicephalus sanguineus, Amblyomma cajennense sensu lato, Amblyomma ovale, Amblyomma parvum, Amblyomma oblongoguttatum, Amblyomma rotundatum, Rhipicephalus (Boophilus) microplus, Haemaphysalis juxtakochi and Amblyomma sp). Polymerase chain reaction products of at least seventeen of these ticks were sequenced and also showed to correspond to \"Candidatus Ricketsia andeanae\", Rickettsia bellii and \"Candidatus Rickettsia amblyommii\". These results suggest that these ricketsias or close-related strains are infecting dogs in Maranhão state, highlighting the potential pathogenicity of these Rickettsia species in northeastern Brazil. At the same time, it differentiates from southeastern Brazil, where sentinel hosts like dogs tend to have higher titers to Rickettsia rickettsii or Rickettsia parkeri, the agents of spotted fever in southeastern Brazil. (AU) | |