Double Trouble in the Tropics: Bacterial–Viral Co-infections in Febrile Patients

Abstract Introduction: Febrile illnesses in endemic regions often involve overlapping bacterial and viral infections, complicating diagnosis and treatment. Co-infections can alter disease severity and lead to suboptimal clinical outcomes, especially where diagnostic resources are limited. Seasonal patterns, particularly during monsoons, may drive these overlaps. Objective: This study investigated trends in bacterial–viral co-infections amongst febrile patients over a defined period, aiming to improve diagnostic approaches and enhance clinical management in resource-limited healthcare settings. Materials and Methods: We conducted a retrospective observational study using laboratory data from febrile patients whose samples were received at Virus Research and Diagnostic Laboratory, Institute of Medical Sciences, Banaras Hindu University, Varanasi, over a defined period. Co-infections were identified based on laboratory-confirmed diagnoses of bacterial and viral pathogens. Results: Dengue virus was the most frequent viral co-pathogen, with 32 and 40 co-infections identified alongside scrub typhus and leptospirosis, respectively. Chikungunya was the next most common, while Influenza and COVID-19 co-infections were rare. No cases involving Japanese Encephalitis virus were observed. Seasonal overlap of bacterial and arboviral pathogens, particularly during monsoons, likely contributed to these patterns. Shared clinical features amongst infections complicate diagnosis and may result in suboptimal treatment. Conclusion: Bacterial–viral co-infections represent a substantial and under-recognised burden in febrile illness management within endemic regions. Our findings underscore the need for integrated, multiplex diagnostic strategies to enhance clinical decision-making and improve outcomes in resource-constrained healthcare settings.