CBC With Differential and Cell Population Data in Prediction of Fever With Thrombocytopenia Syndrome.

Introduction: We aimed to identify additional predictors of severe fever with thrombocytopenia syndrome (SFTS), which has a significantly increasing global incidence.

Methods: This retrospective study included 95 patients with SFTS and 30 healthy individuals. Complete blood count with differential was performed using Sysmex XN 9000 and Mindray BC-6800 Plus analyzers. Extended leukocyte cell population data (CPD) parameters were acquired using a Mindray BC-6800 Plus analyzer. Peripheral smears were identified, and SFTS virus (SFTSV) RNA was detected using real-time reverse transcription polymerase chain reaction.

Results: Of 95 patients with SFTS at admission, 75.8% (72/95) presented leukopenia and 96.8% (92/95) thrombocytopenia with SFTS. Neutrophil left shift and smudge cells (32.4/WBC ± 28.2/WBC) were observed 100% (57/57) on the blood smear. Only 21.1% (21/57) of the reactive lymphocytes were > 5% (3.24% ± 3.35%). Moreover, 33.3% (19/57) of apoptotic lymphocytes and 8.8% (5/57) of nucleated red blood cells were present. Furthermore, 78.9% (45/57) of reactive plasmacytoid lymphocytes increased 3-5 days after admission and 61.1% (11/18) of the patients who died presented with dust blue inclusions in the neutrophils. Compared to the control group, Neu-Y and all lymphocyte and monocyte CPD parameters were significantly higher in all SFTS groups. Compared to the surviving patients with SFTS, Lym-Y in Group 2 (p < 0.05) was significantly lower, but Neu-Y and Mon-Z in Group 3 were higher (p < 0.001) in the death group.

Conclusions: The cell count, peripheral blood morphology, and CPD parameters described in this study had a strong prompting effect on SFTSV infection.