Can Fractional Exhaled Nitric Oxide (FeNO) Serve as a Clinical Indicator for Patients Hospitalized with Crimean-Congo Hemorrhagic Fever?

Crimean-Congo hemorrhagic fever (CCHF), a zoonotic disease spread by infected viruses, can be a significant cause of morbidity and mortality in endemic areas. This prospective study aimed to establish the relationship between fractional exhaled nitric oxide (FeNO) levels and clinical prognosis of CCHF. The study included 85 participants: 55 patients followed up for CCHF from May to August 2022, and 30 healthy controls. FeNO levels were measured upon hospital admission and were 7.6 ± 3.3 parts per billion (ppb) in patients with mild/moderate CCHF, 2.5 ± 2.1 ppb in patients with severe CCHF, and 6.7 ± 1.7 ppb in the healthy control group. There was no statistically significant difference in FeNO levels between the control group and patients with mild/moderate CCHF (P = 0.09), whereas patients with severe CCHF had lower FeNO levels than those in the control group and patients with mild/moderate CCHF (P < 0.001 for both). FeNO measurement may offer a noninvasive and easily applied approach for predicting the clinical course and prognosis of CCHF in the early stages of the disease.