First Evidence of Infection in Horses from Brazil.

The genus includes tick-borne bacterial pathogens affecting humans, domestic and wild mammals. has been identified in different animal species and geographical locations, suggesting that this is a widely distributed and generalist . In the present study, we evaluated infection in 148 Equidae presented to the Medical Clinic Department of a Veterinary Hospital from a midwestern region of Brazil. Blood samples and ticks collected from the animals were tested by Polymerase Chain Reaction (PCR) for the presence of spp. A multigenic approach including Anaplasmataceae-specific (i.e., 16S rRNA, , ) and -specific (i.e., and ) genes was used for accurate bacteria identification. Sera samples were also collected and evaluated for the detection of anti- antibodies by indirect fluorescent antibody test (IFA). Possible associations between molecular and serological diagnostics and clinical and hematological manifestations were tested using chi-squared or Fisher's exact tests. Sequence analysis of the fragment revealed that three horses (2.03%) were exposed to . Sixty-one (41.2%) Equidae (58 equines and three mules), were seropositive for spp., with antibody titers ranging between 40 and 2560. Seropositivity to ehrlichial antigens was statistically associated with tick infestation, rural origin, hypoalbuminemia and hyperproteinemia ( ≤ 0.05). The present study reports the first evidence of natural infection by in horses from Brazil.