Survey of Brazilian spotted fever in dogs and ticks in Itu, São Paulo state, Brazil.

Brazilian Spotted Fever (BSF) is a potentially lethal, tick-borne disease, caused by the bacterium Rickettsia rickettsii. This study investigated the circulation of bacteria of the genus Rickettsia in dogs and ticks in the urban and rural areas of Itu, a BSF-endemic area in southeastern Brazil. During 2017–2018, blood serum samples were obtained from 289 domestic dogs. Through an indirect immunofluorescence assay with antigens of R. rickettsii, R. parkeri, and R. bellii, 21.8% (63/289) of the dogs reacted serologically to at least one Rickettsia species, with endpoint titres ranging from 64 to 2048. A total of 877 ticks were collected from the dogs, being 404 (2 Amblyomma sculptum, 5 A. aureolatum, 1 Amblyomma ovale and 396 R. sanguineus s.l.) tested for the presence of rickettsial DNA by molecular analyses, R. rickettsii was identified in 3 R. sanguineus s.l. from dogs. Our results provide serological and molecular evidence of R. rickettsii infection between dogs and ticks in a BSF-endemic area, where Amblyomma ticks have been previously implicated as vectors of the disease agent, R. rickettsii, to humans, however the role of R. sanguineus s.l. as a vector of R. rickettsii for humans in Brazil cannot be neglected. [ABSTRACT FROM AUTHOR]