Dengue and COVID-19 in the context of co-endemic viral illnesses overlapping symptoms, biomarkers, and diagnostic strategies

Background: The concurrent circulation of Dengue, COVID-19, Zika, and Chikungunya poses major diagnostic challenges due to overlapping symptoms like fever, rash, and myalgia. This review examines clinical, laboratory, and epidemiological distinctions to improve differential diagnosis, especially in co-endemic and low-resource regions. Dengue often presents with thrombocytopenia and elevated AST, while COVID-19 shows lymphopenia and high CRP/D-dimer. Zika and Chikungunya have milder lab changes but share clinical features with the others. Misdiagnosis risks include inappropriate treatment (e.g., anticoagulation in Dengue or delayed respiratory support in COVID-19). Serological cross-reactivity, particularly between Dengue and Zika, further complicates diagnosis. Advances like multiplex PCR, CRISPR diagnostics, and AI-driven tools offer promise, though implementation in low-resource settings remains a barrier. Mobile diagnostic units and algorithm-based triage tools enhance access and early outbreak response. Accurate, timely diagnosis is vital for patient care and public health. Integrated strategies combining clinical assessment with scalable, validated point-of-care technologies are key to mitigating co-epidemic impacts and improving healthcare resilience.