First molecular detection of Borrelia theileri subclinical infection in a cow from Brazil

Borrelia theileri is a relapsing fever group Borrelia that is transmitted to cattle by ticks of the genus Rhipicephalus . In this study, we describe the first molecular detection of B. theileri subclinical infection in a cow in Brazil. During the examination of stained blood smears of 10 cows from a farm with a recent history of fatal Trypanosoma vivax trypanosomiasis, spirochete-like structures were incidentally detected in one of the cows. The animal presented good body score, normal hematocrit and normal-colored ocular mucosa. Temperature, heart rate and respiratory rate were all normal. The animal was infested by ticks, which were morphologically identified as Rhipicephalus microplus . The diagnosis was confirmed by testing DNA extracted from a blood sample using a PCR targeting a ≈ 650 bp fragment of the flagellin B ( flaB ) gene of Borrelia spp. The partial flaB sequence obtained showed 99.83% similarity with B. theileri . Phylogenetically, the flaB partial sequence generated herein clustered with other B. theileri sequences, being separated from B. lonestari . This is the first molecular detection of B. theileri subclinical infection in a cow in Brazil. The possible implications of this finding are discussed.