Analyse the changing epidemiology of dengue in India, including the spread of Aedes mosquitoes into rural areas, and its implications for vector-control policy.

Q. Analyse the changing epidemiology of dengue in India, including the spread of Aedes mosquitoes into rural areas, and its implications for vector-control policy. (15 marks, 250-350 words)

Dengue, an Aedes-borne viral disease with four serotypes (DENV-1 to DENV-4), was long treated as an urban problem. India recorded 2.89 lakh cases in 2023 and 1.21 lakh in 2025 [1], but the more consequential change lies in the disease's shifting geography, serotype mix and vector ecology — each of which unsettles the assumptions on which existing vector control rests.

Changing epidemiology: the shifting profile - Geographic diffusion: transmission has moved beyond metros into semi-urban and rural districts, aided by unplanned urbanisation, unreliable piped water and household storage practices that create breeding habitats [2]. - Climatic drivers: rising temperatures, high rainfall and humidity are extending vector survival and the transmission season [2]. - Serotype churn: shifting serotype dominance matters because a second infection by a different serotype can worsen disease through antibody-dependent enhancement. - Surveillance effect: part of the apparent rise reflects better reporting under the NCVBDC's expanded sentinel network [1] — a caution against reading case counts as pure escalation.

Implications for vector-control policy - Beyond the urban template: source reduction and fogging were designed for dense municipal wards; rural blocks lack comparable entomological and municipal capacity, requiring the NVBDCP to be delivered through PHCs and panchayats. - Water security as vector control: assured piped supply reduces storage, making Jal Jeevan-type interventions de facto anti-dengue measures. - Vaccination as a supplement, not a substitute: CDSCO's 2026 marketing authorisation for Qdenga (Takeda), approved for ages 4–60 in a two-dose schedule [3], and the ICMR–Panacea Biotec DengiAll Phase 3 trial across 19 sites [4], add a preventive tool — but coverage will depend on price and public procurement. - Serotype-wise surveillance must be strengthened to guide both vaccine deployment and outbreak response.

Dengue in India is thus becoming a decentralised, climate-sensitive and serotype-dynamic challenge rather than a seasonal metropolitan one. Policy must correspondingly shift from episodic spraying to an integrated model combining year-round surveillance, water and sanitation reform, community participation and calibrated vaccine introduction — advancing SDG 3's target on ending epidemics of neglected tropical diseases.

(~330 words)

Sources: 1. Dengue Situation in India — National Center for Vector Borne Diseases Control (NCVBDC), MoHFW — year-wise dengue cases and deaths; national surveillance framework 2. Dengue and severe dengue — WHO Fact Sheet — urbanisation, water storage and climate as drivers of geographic spread 3. CDSCO Approves India's First Dengue Vaccine, Strengthening National Dengue Prevention Efforts — PIB — Qdenga approval, age group 4–60, two-dose regimen 4. ICMR and Panacea Biotec initiate the First Dengue Vaccine Phase 3 Clinical Trial in India with Indigenous Dengue Vaccine, DengiAll — PIB — indigenous vaccine Phase 3 trial across 19 sites