Evaluation of Serum Level of Interleukin-6 in Patients With Crimean-Congo Hemorrhagic Fever in Zahedan, Iran, From 2012 to 2015

Abstract

Background: Crimean-Congo hemorrhagic fever (CCHF) is caused by a tick-borne virus in the family of Bunyaviridae. It is asymptomatic in infected animals, but it can cause severe hemorrhagic disease in human with mortality rate of 3% to 50%. Viral load and inflammatory cytokines have an important role in the pathogenesis of the disease. Objectives: The current study aimed to investigate the level of interleukin (IL)-6 in patients with CCHF and the relationship of its level with the severity of infection and clinical outcome of patients with CCHF. Patients and Methods: This cross-sectional and prospective study evaluated all patients with confirmed CCHF admitted to Boo-Ali hospital in Zahedan, Southeast of Iran, from March 2012 to Jan 2015. The disease was confirmed by enzyme-linked immunosorbent assay (ELISA) IgM and IgG and /or real time polymerase chain reaction (RT-PCR). Also, a blood sample was drawn on the day of admission to test the level of IL-6 in the serum of patients. Then, the relationship between serum level of IL-6 with the severity of disease and clinical outcome in patients was evaluated. Data was analyzed by Mann-Whitney test and a P < 0.05 was considered significant. Results: Among 50 patients with CCHF (38% female, 62% male with the age range of 18 - 63 years), the serum level of IL-6 was higher than normal (7 pg/mL) in 60% of the patients. According to the severity index disseminated intravascular coagulation score (DIC score), the mean serum level of cytokine in the mild and severe disease were 50.2 ± 79.4 and 127.3 ± 100.2, respectively. There was a significant difference between serum level of IL-6 and severity of disease (P = 0.003). There was no mortality in patients with low or normal serum levels of IL-6. But, in patients with a high serum level of IL-6, seven patients died. Conclusions: Based on the obtained results, it was concluded that a diminished immune response caused by cytokines in acute phase response, can lead to dissemination of virus, severity of illness and increase of the mortality rate.