Epidemiologic study of Rickettsia felis in endemic and nonendemic areas for spotted fever in the State of São Paulo

Author(s)

Mauricio Claudio Horta

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2006-05-18

Examining board members

Teresinha Tizu Sato Schumaker; Solange Maria Gennari; Marcelo Bahia Labruna; Pedro Marcos Linardi; Luiz Jacintho da Silva

• Advisor: Teresinha Tizu Sato Schumaker

Abstract

Recent studies have showed the presence of Rickettsia felis, a spotted fever group Rickettsiae, in human blood with clinical signs compatible with spotted fever and in infected fleas. This work aims to determine the prevalence of R. felis in potential vectors (fleas and ticks) and reservoirs (opossums, dogs, cats, equines and humans) from endemic (Mogi das Cruzes, Pedreira, Piracicaba e São Paulo), and non-endemic (Pirassununga) areas for spotted fever in the State of São Paulo. Molecular probes (polimerase chain reaction and DNA sequencing), serologic diagnoses and cell culture were used. From trapped opossums (Didelphis aurita and Didelphis albiventris) a total of 312 fleas, belonging to Family Pulicidae (141), Rhopalopsyllidae (170) and Ctenophthalmidae (1) and 709 ticks (Amblyomma spp and Ixodes loricatus) were collected. On dogs a total of 212 fleas (Ctenocephalides felis felis) and 115 ticks (Amblyomma cajennense, Amblyomma aureolatum and Rhipicephalus sanguineus) were collected. On cats, 66 fleas (59 C. felis felis and 7 Rhopalopsyllus lutzi lutzi) and 10 ticks (R. sanguineus and Amblyomma spp) were collected. Blood samples were collected from 94 opossums, 55 dogs, 25 cats, 85 equines and 238 humans. Rickettsia felis was detected in 42-45,8% of the C. felis felis collected on opossums, dogs and cats. This same Rickettsia species was detected in 4% of Polygenis (N.) atopus fleas, and 1,8% and 0,7% of I. loricatus and Amblyomma spp ticks, respectively, collected from opossums. Rickettsia bellii was found in ticks I. loricatus (59,1%), A. dubitatum (8,7%) and Amblyomma spp (0,9%) and in a flea P. (N.) atopus (1%). No Rickettsia DNA was detected in animal or human blood samples. However antibodies against Rickettsia rickettsii, Rickettsia parkeri, R. felis and R. bellii were detected in all locations. The titers suggest infection by R. rickettsii in opossums, dogs, equines and humans and by R. parkeri in opossums, dogs and equines. R. felis and R. bellii were isolated and cultivated with the C6/36 and VERO cells, respectively. (AU)