## Dengue Virus Serotypes in India **Key Point:** DENV-2 is the most frequently isolated serotype in dengue epidemics across India, followed by DENV-1 and DENV-3. DENV-4 remains rare in the Indian subcontinent. ### Epidemiological Distribution | Serotype | Prevalence in India | Clinical Severity | Epidemic Pattern | |----------|-------------------|------------------|------------------| | DENV-2 | Most common (40–50%) | Moderate to severe | Frequent epidemics | | DENV-1 | Common (20–30%) | Mild to moderate | Co-circulates with DENV-2 | | DENV-3 | Moderate (10–20%) | Mild to moderate | Sporadic outbreaks | | DENV-4 | Rare (<5%) | Mild | Isolated cases | **High-Yield:** DENV-2 was the predominant serotype during the major 2015–2016 dengue outbreak in Delhi and has remained the leading cause of dengue epidemics in urban India. ### Geographic and Temporal Trends - **Urban areas:** DENV-2 and DENV-1 co-circulate; DENV-2 shows higher epidemic potential. - **Seasonal pattern:** Peak transmission during monsoon and post-monsoon months (July–November). - **Serotype replacement:** Periodic shifts occur; DENV-1 surged in 2006–2007, DENV-2 dominated 2015–2016, DENV-3 emerged in 2009–2010. **Clinical Pearl:** Secondary dengue infection with a different serotype carries higher risk of dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) due to antibody-dependent enhancement (ADE). [cite:Park 26e Ch 8]
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