First sequence-confirmed detection of Ehrlichia minasensis in Rhipicephalus microplus from cattle in Costa Rica

Ehrlichia minasensis is an emerging tick-borne bacterium associated with cattle and Rhipicephalus microplus. It has been reported in South America and, more recently, in Panama, but sequence-confirmed evidence from Costa Rica has not been documented. In this short communication, we screened 19 adult R. microplus ticks collected opportunistically from four cattle at three locations in Costa Rica, together with two available corresponding EDTA blood samples. DNA from ticks and blood was tested by conventional PCR targeting the dsb and groEL genes of Ehrlichia spp. Amplicons compatible with Ehrlichia spp. were selected for sequencing and phylogenetic analysis. One adult female tick was positive by groEL PCR, whereas both available bovine blood samples and all remaining ticks tested negative. No amplification was obtained for the dsb target. The 492-bp sequence showed 100% nucleotide identity with an E. minasensis sequence from Colombia (MW548512.1) and clustered within the E. minasensis clade. Because sampling was opportunistic and limited in size, these findings should not be interpreted as evidence of prevalence, host-level infection frequency, or vector competence in Costa Rica. Nevertheless, this study provides sequence-confirmed evidence of E. minasensis in R. microplus from cattle in Costa Rica, expands the documented geographic distribution of this bacterium in Central America, and supports the need for broader surveillance in cattle-tick systems.