Evaluation of the role of serum DcR3 levels in the early clinical prognosis of patients with Crimean-Congo hemorrhagic fever

Background: Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic disease that is transmitted by Hyalomma ticks and is endemic in many parts of the world. This study aimed to determine the relationship between early serum Decoy receptor-3 (DcR3) level and clinical severity in patients with CCHF.Methods: The study included 88 patients hospitalized for CCHF between April and August 2022 and a control group of 40 healthy individuals. The patients were divided according to clinical course as those with mild/ moderate (group 1, n = 55) and severe (group 2, n = 33) CCHF. DcR3 levels were measured by enzyme-linked immunosorbent assay of serum obtained at the time of diagnosis. Results: Fever, hemorrhage, nausea, headache, diarrhea, and hypoxia were significantly more common among patients with severe CCHF than patients with mild/moderate CCHF (p < 0.001, <0.001, 0.02, 0.01, <0.001, and < 0.001, respectively). Group 2 had higher serum DcR3 levels than both group 1 and the control group (p < 0.001 for both). Serum DcR3 levels were also significantly higher in group 1 than in the control group (p < 0.001). Using 98.4 ng/mL as the cut-off value, serum DcR3 had 99% sensitivity and 88% specificity in differ-entiating patients with severe CCHF from those with mild/moderate CCHF.Conclusion: During the high season in our endemic region, CCHF can present with a severe clinical course in-dependent of age and comorbidities, unlike other infectious diseases. Elevated DcR3 observed early in the disease may allow additional immunomodulatory therapies to be tried in addition to antiviral therapy in CCHF, for which treatment options are limited.