Prevalence and Clinical Impact of Dengue–Malaria Co-Infection Among Adults with Acute Febrile Illness in Islamabad, Pakistan: A Cross-Sectional Study

Background: Pakistan is highly endemic for both dengue and malaria infections, particularly during monsoon and post-monsoon periods. The clinical manifestations of dengue and malaria frequently overlap. This overlap complicates early clinical differentiation, particularly in resource-limited settings. Understanding the prevalence and clinical implications of dengue–malaria co-infection in Islamabad is essential for refining diagnostic algorithms and optimizing resource allocation. Objective: 1. To determine prevalence of dengue–malaria co-infection 2. To assess association with severity. Methods: Cross-sectional study was conducted in the Department of Medicine at the Federal Government Polyclinic Hospital (FGPC), Islamabad, from September to December 2025 of 92 adults with laboratory-confirmed dengue. Malaria infection was confirmed by peripheral blood smear (thick and thin film microscopy) and/or rapid immunochromatographic testing. Based on laboratory findings, patients were classified into: Dengue mono-infection Dengue–malaria co-infection Demographic characteristics and laboratory parameters including hemoglobin (HB), hematocrit (HCT), platelet count (PLT), alanine aminotransferase (ALT), serum albumin, and creatinine (CR) were recorded using a structured proforma. Statistical analysis was performed using SPSS version 25 Results: Co-infection prevalence was 15.2%. Severe disease occurred in 57.1% vs 42.3% (p=0.385). Elevated ALT independently predicted severe disease (OR 1.009, 95% CI 1.001-1.016, p=0.020). AUC for ALT was 0.628. Conclusion: Dengue–malaria co-infection was identified in 15.2% of adults with laboratory-confirmed dengue in Islamabad. Although co-infected patients demonstrated numerically higher rates of severe disease, co-infection was not independently associated with severity in multivariable analysis. Elevated ALT emerged as an independent predictor of severe disease and may serve as a useful biochemical marker for clinical risk stratification.