A 28-year-old woman from a dengue-endemic district in Tamil Nadu presents with fever, myalgia, and a characteristic rash on day 5 of illness. Under NVBDCP surveillance, which is the most common serotype of dengue virus responsible for dengue fever in India?

Explanation

## Dengue Serotypes in India — NVBDCP Epidemiology **Key Point:** Dengue virus serotype 2 (DENV-2) is the most frequently isolated and most common serotype responsible for dengue fever cases in India, accounting for the majority of laboratory-confirmed dengue cases under NVBDCP surveillance. ### Dengue Serotype Distribution in India | Serotype | Frequency in India | Clinical Manifestation | Epidemiologic Trend | | --- | --- | --- | --- | | DENV-2 | Most common (40–50%) | Dengue fever, DHF/DSS | Consistently prevalent, urban foci | | DENV-1 | Common (25–35%) | Dengue fever, DHF/DSS | Co-circulating, seasonal peaks | | DENV-3 | Moderate (10–20%) | Dengue fever, DHF/DSS | Sporadic, regional outbreaks | | DENV-4 | Least common (<5%) | Dengue fever, mild disease | Rare, limited geographic spread | ### Epidemiologic Features of DENV-2 in India - **Urban predominance:** Aedes aegypti breeding in urban water containers. - **Seasonal pattern:** Peak transmission during monsoon and post-monsoon (June–November). - **Geographic distribution:** Pan-India, with highest burden in metropolitan areas (Delhi, Mumbai, Bangalore, Chennai). - **Genetic variation:** Multiple genotypes circulating; some show enhanced virulence. **High-Yield:** NVBDCP laboratory surveillance (NS1 antigen, RT-PCR, serology) consistently reports DENV-2 as the dominant serotype. All four serotypes can cause dengue fever, dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS), but DENV-2 is most frequently associated with outbreaks. **Clinical Pearl:** The patient's presentation (fever, myalgia, rash on day 5) is classic dengue fever. Serotype identification is important for outbreak response and vaccine strategy planning, though clinical management does not differ by serotype. **Warning:** Do not assume all dengue cases are caused by a single serotype. Co-circulation of multiple serotypes is common in endemic areas, and secondary infection with a different serotype increases risk of severe dengue.