Thrombocytopenia is an important pathological feature of HFRS（Hemorrhagic Fever With Renal Syndrome, HFRS）. However, the cause of thrombocytopenia in HFRS is not yet fully understood. Neutrophils, as the largest number of white blood cells in the human body, can widely participate in the immune process of viral infections. Previous studies have found that the neutrophils of patients with acute myocardial infarction can interact with activated platelets and further mediate platelet phagocytosis.Therefore, this study aims to systematically elucidate the immunological process of neutrophil mediated thrombocytopenia in patients with HFRS by exploring the correlation between platelet activation, neutrophil activation and neutrophil proportion of adherent / phagocytic platelets peripheral blood of HFRS patients, and to analyze its relationship with the course of HFRS disease, which lays a theoretical foundation for further understanding the pathogenesis of HFRS and provides a basis for clinical use.

Inclusion Criteria:

• Age ≥18 years;
• Clinical diagnosis meets the diagnostic criteria of the national HFRS prevention and treatment plan (Hantavirus-specific IgM antibody is positive). The classification and staging standards of HFRS patients are based on the "Expert Consensus of Shaanxi Province on Diagnosis and Treatment of Hemorrhagic Fever with Renal Syndrome".

Exclusion Criteria:

• Age <18 years;
• Have a history of kidney disease;
• Have a history of liver disease;
• Have a history of malignant tumor;
• Receive dialysis treatment before admission;
• Combined with hypertension, coronary heart disease and diabetes history;
• Combined with HIV infection and patients with autoimmune diseases and pregnancy.

This project intends to collect about 160 inpatients (the First Affiliated Hospital of Xi'an Jiaotong University) who were diagnosed with HFRS between 2021.01-2023.06 for follow-up research, including about 40 cases of light, medium, severe, and critical. 40 healthy people served as normal controls.