Rickettsia tillamookensis-like strain in brown dog ticks in Brazil.

Brown dog ticks (Rhipicephalus linnaei) collected from dogs in northeastern Brazil in 2015 tested positive for a rickettsial organism phylogenetically related to Rickettsia tillamookensis (referred to as R. tillamookensis-like). One of the dogs with R. tillamookensis-like-positive ticks tested positive for IgG antibodies to Rickettsia rickettsii antigens, suggesting a potential reaction to spotted fever group rickettsiae. Future research should assess whether the rickettsia detected herein is R. tillamookensis or a closely related species, its distribution, potential vectors, and possible pathogenicity to humans.