Temporal Dynamics of Viremia in Hemorrhagic Fever With Renal Syndrome Patients

The pathogenesis of hemorrhagic fever with renal syndrome (HFRS) remains incompletely understood. Currently, the clinical diagnosis of HFRS primarily relies on epidemiological history and clinical presentation, while the confirmation of HFRS depends mainly on the detection of hemorrhagic fever antibodies. As a viral disease, etiological diagnosis has yet to be widely implemented in clinical practice. We conducted a prospective study to characterize the temporal pattern of viremia in patients with HFRS and to explore the relationship between viral load and key laboratory parameters. Demographic and clinical data were collected from HFRS patients admitted to Tangdu Hospital, The Fourth Military Medical University, between December 2021 and December 2022. Serum samples obtained at different illness stages were tested for viral load using RT-PCR, and corresponding laboratory results were analyzed. A total of 61 patients were enrolled, providing 256 serum samples. Both viral detection rate and viral load decreased with disease progression, with viremia detectable up to day 22. Regardless of clinical severity, Hantaan virus (HTNV) RNA load declined over time. Viral load was positively correlated with white blood cell count, lymphocyte count, and monocyte count (r = 0.428, 0.485, and 0.318, respectively; all p < 0.001), negatively correlated with platelet count (r = -0.507, p < 0.001), and showed weak correlations with hemoglobin and neutrophil count. Additionally, viral load was negatively correlated with fibrinogen (r = -0.502, p < 0.001) and weakly correlated with prothrombin time, activated partial thromboplastin time, and prothrombin activity; it was positively correlated with the aspartate aminotransferase-to-platelet ratio index (r = 0.515, p < 0.001). In conclusion, viremia occurs early in HFRS onset, can persist for more than 2 weeks, and viral load is an important indicator for early diagnosis of HFRS.