Crimean-congo hemorrhagic fever in Iraq, 2021-2024: epidemiological and clinical data analysis with proposed severity...

Crimean-Congo hemorrhagic fever (CCHF) is a high-fatality zoonotic infection. Iraq has experienced a substantial increase in reported CCHF cases since 2021, yet predictors of mortality and the feasibility of existing severity scores in routine care have not been systematically assessed. We aimed to identify demographic, clinical and laboratory predictors of death among confirmed CCHF patients in Iraq and to develop a simplified severity score suitable for bedside use in resource-constrained settings.

We analyzed 273 laboratory-confirmed CCHF cases with known outcomes reported to the Iraqi national surveillance system from 1 January 2021 to 31 December 2024 (273/1,193 confirmed cases with complete standardized forms). Demographic, exposure, clinical, and laboratory variables (including platelet count and cycle threshold [Ct] values) were extracted from harmonized Ministry of Health and Central Public Health Laboratory databases. Univariable and multivariable logistic regression were used to identify mortality predictors. Receiver Operating Characteristic (ROC) curve analysis compared the discriminative performance (area under the curve, AUC) of newly proposed scores with existing CCHF Severity Scoring Index (SSI) and Swanepoel's Grading Score (SGS).

The overall case fatality rate was 12.1% (33/273). Age, sex, occupation, place of residence, and exposure history were not significantly associated with mortality. In univariable analysis, low platelet count (< 20 × 10³/µL), high viral load (Ct ≤ 25), epistaxis, gastrointestinal bleeding, any bleeding, and jaundice were associated with increased odds of death; after false discovery rate correction, epistaxis, gastrointestinal bleeding, any bleeding, and jaundice remained significant. In multivariable analysis, only epistaxis retained an independent association with mortality (adjusted OR 4.70; 95% CI 1.08-20.4). A laboratory-enhanced three-variable score (epistaxis, low platelet count, Ct ≤ 25) achieved an AUC of 0.70, similar to SSI (0.69). A two-variable score (epistaxis + low platelet count) had an AUC of 0.69, and a purely clinical score (epistaxis, any bleeding, jaundice) an AUC of 0.62, close to SGS (0.64).

Epistaxis and jaundice emerged as pragmatic clinical red-flag indicators of poor outcome, with low platelet count and high viral load supporting risk stratification where available. Very simple, clinically based scores performed comparably to existing complex tools and may facilitate earlier triage and intensified supportive care for high-risk CCHF patients in resource-limited settings.