Isolation of Rickettsia rickettsii and Rickettsia bellii in cell culture from the tick Amblyomma aureolatum in Brazil.

Brazilian spotted fever (BSF) is a highly lethal disease caused by Rickettsia rickettsii. In the present study, rickettsial infection was evaluated in 669 Amblyomma aureolatum adult ticks collected from naturally infested dogs in Taiaçupeba, a BSF-endemic area in the state of São Paulo. Ten (1.49%) ticks were infected with Rickettsia bellii, and 6 (0.89%) ticks were infected with R. rickettsii. Both Rickettsia species were isolated and established in Vero cell cultures. The Rickettsia isolates were characterized by molecular analyses, sequencing fragments of different rickettsial genes. Our results suggest that A. aureolatum is an important vector of R. rickettsii in Brazil.