In vitro evaluation of the automated hematology analyzer XN-31 for rapid diagnosis of equine piroplasmosis

Equine piroplasmosis (EP) is a protozoal disease affecting equids, caused by Theileria equi and Babesia caballi . EP is conventionally diagnosed using microscopic, molecular, and/or serological methods, which are time-consuming. Consequently, there is a need for faster testing methods. In this study, we evaluated the application of the Sysmex XN-31 automated hematology analyzer, originally a rapid test for detecting malaria in humans, for the diagnosis of EP. The cultured parasites were measured using the XN-31 that had been customized for horse blood samples (XN-31m). The following parameters were evaluated: limit of detection (LoD), limit of quantification (LoQ), linearity, carryover, precision, and correlation with microscopic examination. The XN-31m detected infected red blood cells (RBCs) in approximately 1 minute. The LoD and LoQ for B. caballi were 4.54 infected RBCs/μL and 14.10 infected RBCs/μL, while those for T. equi were 5.80 infected RBCs/μL and 11.44 infected RBCs/μL, respectively. Linearity showed excellent correlation ( R 2 > 0.99), and carryover never exceeded 0.5%. The coefficient of variation was under 5%. The correlation between the results obtained using XN-31m and microscopic examination was high ( R 2 > 0.98). In conclusion, the XN-31 analyzer detected B. caballi and T. equi parasites in approximately 1 minute with high sensitivity. The results indicate the potential of the XN-31 analyzer as a fast and user-friendly diagnostic method for EP. IMPORTANCE In this study, we demonstrated that the automated hematology analyzer, XN-31, can detect red blood cells infected with Babesia caballi and Theileria equi in about 1 minute. We evaluated the diagnostic performance of the XN-31 analyzer for equine piroplasmosis, providing evidence of its potential as a diagnostic tool for this disease.