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| Author(s): |
Felipe da Silva Krawczak
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: | 2016-08-05 |
| Examining board members: |
Marcelo Bahia Labruna;
Solange Maria Gennari;
Fabio Gregori;
Vanessa do Nascimento Ramos;
Matias Pablo Juan Szabo
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| Advisor: | Marcelo Bahia Labruna |
| Abstract | |
In 2005 the first Brazilian Spotted Fever (BSF) case was confirmed in the Rio Grande do Sul (RS) state, Brazil. Ever since until April 2016, twelve cases have been confirmed, and four of them are native from Cerro Largo city, an area considered endemic to the riquetsial illness. During the same period, RS also notified 58 suspected cases to the Ministry of Health. There are two distinct biomes in RS, Atlantic Forest and Pampa, the later restricted to RS within the Brazilian land. Until now, no studies reported rickettsial infection in the ixodofauna of RS. Thus, this study aimed to investigate the rickettsial infection of Spotted Fever Group (SFG) in dogs, small mammals and ticks; by immunofluorescence assay (IFA), qPCR and attempted rickettsial isolation in cell culture from ticks collected in an endemic area (Cerro Largo) and non-endemic areas in Pampa and Atlantic Forest biomes of RS. Through serology (IFA), 33.5% (55/164), 2.9% (1/33) and 40% (16/40) small mammals, and 8.3% (3/36), 13.9 % (5/36) and 20.4 (28/137) dogs from the Atlantic Forest, Pampa, and BSF-endemic area, respectively, were seroreactive (titer ≥64) to at least one of the six rickettsia antigens tested. Eight species of ticks were collected in the Atlantic Forest: Amblyomma aureolatum, Amblyomma brasiliense, Amblyomma incisum, Amblyomma ovale, Haemaphysalis juxtakochi, Ixodes loricatus, Rhipicephalus microplus and Amblyomma yucumense, the later described as a new species. In the Pampa fragment, four tick species were found (A. aureolatum, A. ovale, Amblyomma tigrinum and Rhipicephalus sanguineus), and five tick species (Amblyomma dubitatum, Amblyomma longirostre, A. ovale, I. loricatus, R. microplus) in the BSF-endemic area of RS. We performed the first molecular detection in the RS state of "Candidatus Rickettsia amblyommii" in A. longirostre and A. brasiliense; "Candidatus Rickettsia andeanae" in A. aureolatum and A. tigrinum; Rickettsia bellii in I. loricatus; Rickettsia rhipicephali in A. yucumense and H. juxtakochi; and "Candidatus Rickettsia asemboensis" in fleas in Brazil. Noteworthy, we detected the pathogen Rickettsia sp. strain Atlantic rainforest in A. ovale ticks from Cerro Largo (endemic area for BSF in RS). We also performed the first isolation in cell culture of rickettsia from RS state, which comprised R. bellii from I. loricatus collected in the Atlantic Forest and the BSF-endemic area. This study is the first comparative research about rickettsiae among Pampa and Atlantic Forest biomes, and also the first molecular detection and isolation in cell culture of rickettsiae from Rio Grande do Sul, Brazil (AU) | |
| FAPESP's process: | 12/21915-4 - Survey for rickettsial infection of the spotted fever group in dogs, small mammals and ticks in endemic and non-endemic areas of the Pampa and Atlantic forest biomes in the state of Rio Grande do Sul. |
| Grantee: | Felipe da Silva Krawczak |
| Support Opportunities: | Scholarships in Brazil - Doctorate |