Prevalence and factors associated with dengue fever serotypes in Eastern Sudan: a hospital-based cross-sectional...

Dengue is a critical public health threat in Sudan, exacerbated by rapid urbanization and climatic factors. The 2024 outbreak in Kassala State occurred amidst a violent internal conflict and massive population displacement, synergistically accelerating transmission and complicating clinical management. This study aimed to determine the prevalence of dengue virus (DENV) serotypes and identify sociodemographic and clinical factors associated with specific serotypes among residents and internally displaced persons (IDPs) in Kassala during the 2024 epidemic.

A hospital-based cross-sectional study was conducted at Kassala Teaching Hospital (October-December 2024). Serum samples from 227 confirmed dengue patients (RDT-positive for NS1, IgM, or both) were analyzed using one-step Real-Time PCR for serotyping. Univariate and multivariate logistic regression analyses were performed to identify factors associated with the most prevalent serotypes.

Among the confirmed 227 dengue fever, DENV-2 was the dominant serotype (59.9%), followed by DENV-3 (35.2%) and DENV-1 (4.8%). Notably, 52% of patients were IDPs, and 30.4% presented with severe forms (DHF/DSS). The overall mortality rate was 6.6%, with 13 out of the 15 recorded deaths occurring among the displaced population. While a high fatality rate was noted among the small subset of DENV-1 patients (4 out of 11), this finding must be interpreted with extreme caution due to the limited sample size. Multivariate analysis revealed that the non-use of mosquito nets was the only independent factor associated with DENV-2 infection (adjusted odds ratio, AOR = 2.20; 95% CI: 1.23-3.90; P = 0.007). No significant differences were found between serotypes regarding age, gender, or displacement status.

The 2024 dengue outbreak marked a significant shift from DENV-3 to DENV-2 dominance, with a high mortality burden clustering heavily within vulnerable IDPs due to systemic displacement factors rather than strain dominance. The strong association between net non-use and DENV-2 highlights the urgent need for targeted long-lasting insecticidal nets (LLINs) distribution and vector control in displacement camps. Additionally, the high fatality rate in the small DENV-1 subset underscores the necessity of strengthened molecular surveillance to monitor virulent strains in conflict zones.