Viral Load as a Predictor of Severity in Crimean-Congo Hemorrhagic Fever

Abstract

Background: Crimean-Congo hemorrhagic fever (CCHF) is an endemic disease in south eastern of Iran, especially in Sistan and Baluchestan province. CCHF is a potentially fatal disease. Many factors are suggested for the prediction of severity in this disease. Objectives: In this study, the viral load in patients admitted to Boo-Ali hospital was determined and the association between viral load and disease severity was evaluated based on DIC severity score in patients with CCHF. Methods: In this analytical cross-sectional study, we studied patients with confirmed CCHF who were admitted to Boo-Ali hospital, Zahedan, from September 2012 to March 2014. The patients were divided into two groups based on DIC severity score. Then, the viral load in the patients was measured by using RNA as a template for RT-PCR (QIAgene OneStep SYBR GREEN qRT-PCR smart mix) and finally, the two groups were compared. The results were analyzed using SPSS 20.0 (SPSS Inc.). To investigate the correlation between viral load and disease severity, and also to find the viral load differentiating mild cases from severe cases, ROC curve, Mann–Whitney U test, and Independent t-test were used. Results: The total number of patients with confirmed CCHF under the subject of study was 37 (84% male and 16% female) in age range of 17 to 58 years (31.1 ± 12.2). The mean viral loads on the first and fifth days of admission were 1.3 × 106 and 3.7 × 105 copies/mL, respectively. After grouping patients based on DIC severity, the mean viral load on the first day of admission was 3.2 × 105 copies/mL in the mild CCHF group and 4.3 × 106 copies/m in the severe CCHF group. The viral load had a direct correlation with CCHF severity (P ≤ 0.001). Serum viral load that differentiated between mild and severe cases of CCHF was determined as 8.6 × 105 copies/mL with sensitivity of 100%, specificity of 92%, positive predictive value of 82%, and negative predictive value of 100%. Conclusions: The viral load in patients who suffer from CCHF has a direct significant correlation with disease severity. Viral load above 8.6 × 105 copies/mL on the first day of admission is a predictor of severe CCHF.