Introduction
Crimean–Congo hemorrhagic fever (CCHF) is an endemic disease in the Northern Anatolia Region of Turkey that is characterized by fever and hemorrhage and can have a severe and potentially life-threatening course1. The CCHF virus is generally transmitted to humans through tick bites or contact with infected ticks or the bodily fluids of infected animals. The main targets of CCHF are mononuclear phagocytes, endothelial cells, and hepatocytes 2. Signs and symptoms occur as a result of the effect of the virus on target organs. Sudden-onset fever, headache, malaise, anorexia, widespread body pain, and nausea are the most common symptoms3.
The pathogenesis of CCHF is not fully understood, though macrophage activation and hemophagocytosis are known to be the basis of the pathological process. After entering the body, the virus proliferates in local lymph nodes and tissues, then spreads via the lymph and monocytes to other parts of the body, especially the spleen, liver, lymph ganglia, lungs, adrenal glands, and endothelium 4. Secondary infection of parenchymal cells occurs by macrophage migration. Macrophage and endothelial cell activation induces inflammatory and vasoactive processes, resulting in systemic inflammatory response syndrome (SIRS) 5. Coagulation system activation and extensive fibrin accumulation in the vascular beds lead to disseminated intravascular coagulation (DIC) and multiple organ failure (MOF)2.
Blood gas analysis is important for evaluating prognosis in SIRS and MOF. Studies have shown that low pH, high lactate, and low carboxyhemoglobin levels in venous blood gas analysis are important markers of clinical course and prognosis 6. In particular, lactate level is a serum marker frequently used in clinical practice. High serum lactate is an indicator of tissue hypoperfusion. Lactate is produced by many tissues of the human body and at high levels in muscle tissue. Under normal circumstances, lactate is rapidly eliminated by the liver and partly by the kidneys 7.
Procalcitonin level is believed to increase mostly in bacterial infections and sepsis as part of the systemic inflammatory response against infection. It is generally not expected to increase in response to viral infections. However, it has been suggested that a major increase in cytokine levels may lead to procalcitonin elevation8.
The aim of our study was to evaluate the relationship between procalcitonin level and venous blood gas parameters and the clinical course and prognosis of CCHF.