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Although national guidelines have a well-defined framework for entomological surveillance, gaps persist in year-round implementation at district and zonal levels, hindering effective dengue control.
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Dengue is not only becoming more common but is also spreading into previously unaffected areas in India. It is transmitted by the bite of Dengue Virus(DENV) infected mosquitoes, with Aedes albopictus and Aedes aegypti as primary vectors. According to the World Health Organisation (WHO), India was among the 30 most highly endemic countries in the world in 2025 for dengue. As dengue spreads into rural and peri-urban areas, surveillance systems originally designed for urban zones are proving inadequate.
No specific medicine is available to treat dengue yet; only standard supportive care. Currently, there are two licensed vaccines, i.e. CYD-TDV (Dengvaxia)and TAK-003 (Qdenga), for dengue prevention. The revised guidelines of WHO, which came in April 2018, say that CYD-TDV can be used only on seropositive individuals. WHO recommends the use of Qdenga in children aged 6–16 years in places with high intensity of dengue transmission. India's first indigenous dengue vaccine, i.e. DengiAll, is in Phase III trials. Due to the absence of specific treatments and the limited reach of vaccines, entomological surveillance remains the most effective tool for dengue prevention. Entomological surveillance is a crucial part of India’s Integrated Vector Management (IVM) strategy. However, it remains under-resourced and not sufficiently integrated into routine dengue control, despite having strong practices in certain states. The lack of convergence, health worker gaps, and systematic monitoring in entomological surveillance have undermined early detection and timely response mechanisms essential for dengue prevention. With rising dengue incidence and geographic spread, strengthening entomological surveillance has become central to India’s preventive strategy.
Entomological surveillance provides data to predict dengue outbreaks and can help in preventing them. It includes a range of approaches that vary in complexity, precision, and cost, from traditional larval surveys to advanced techniques and molecular tools. The larval and pupal surveys are simple, low-cost, and feasible to conduct across various settings, making them the foundation of surveillance efforts in India. However, they provide only indirect and limited insights into adult mosquito populations and actual dengue transmission risk.
The lack of convergence, health worker gaps, and systematic monitoring in entomological surveillance have undermined early detection and timely response mechanisms essential for dengue prevention.
In contrast, advanced surveillance techniques such as adult mosquito trapping and insecticide resistance testing provide more direct data. These methods can inform targeted vector control strategies and monitor the effectiveness of insecticides. Emerging tools, such as molecular xenomonitoring, facilitate early detection of arboviruses within wild mosquito populations and offer predictions for future outbreaks. Yet, these technologies remain mostly confined to research laboratories because of high costs and infrastructural limitations.
In India, the National Centre for Vector Borne Diseases Control (NCVBDC) administers an umbrella programme, namely, the National Vector Borne Diseases Control Programme (NVBDCP), for the prevention and control of vector-borne diseases. For entomological surveillance, NCVBDC formulates policies, guidelines, training modules and surveillance standards. The Indian Council of Medical Research (ICMR) supports entomological research and epidemiological research. State health departments adapt national guidelines into operational plans, coordinating with urban local bodies (ULBs) for implementation. Municipalities are primarily responsible for implementing this surveillance, often supported by health departments and community mobilisation initiatives through Accredited Social Health Activists (ASHAs) and school awareness campaigns (for example, ICMR Puducherry’s Dengue Connect app and DREAMS Project).
Despite well-defined frameworks, entomological surveillance is often reactive, intensifying only during outbreaks rather than maintaining year-round surveillance. Interviews conducted with government experts suggest that the coordination between some state health departments and their laboratories with national centres, as well as between municipalities and local health systems, is inconsistent, which leads to fragmented efforts in vector control and data sharing. Limited human resources, inadequate entomological expertise, and poor intersectoral convergence further weaken the efficiency of surveillance. Thus, while the institutional architecture and guidelines for entomological surveillance in India appear robust on paper, their operational translation is uneven and largely outbreak or flood-driven. The studies conducted in Odisha and Rajasthan have demonstrated insecticide resistance among Aedes mosquitoes. There is a severe lack of monitoring and supervision in insecticide spraying/fogging, which is considered a good strategy for vector control.
Several community-level studies have been recently conducted, as illustrated in Table 1, which have demonstrated the potential for predictive entomology but have remained isolated efforts.
Table 1: Summary of the recent evidence generated through entomological surveillance in some parts of India for Early Warnings and Virus Detection
|
Location and date of study |
Major Findings |
Evidence Generated |
|
In this survey, Aedes aegypti accounted for approximately. 64 percent of mosquitoes in water-holding containers. |
Very high vector density; urgent need for targeted vector control and mapping of high-risk zones. |
|
|
All larval indices (HI, CI, BI) peaked in July-August. Breeding is highest in plastic containers (39.26 percent), then earthen pots (20.09 percent) and coolers (17.80 percent). |
Emphasised that domestic containers, especially plastic ones, are key breeding sites; timing of interventions pre-monsoon/monsoon is critical. |
|
|
In this survey, Aedes albopictus comprised approximately 85 percent of the total Aedes specimens collected. |
Suggested shift in species composition, which requires a change in vector control strategies. |
|
|
Study found high Stegomyia indices; multiple mosquito breeding habitats, including flower pots, fridge trays, plastic barrels, and rubber tyres. |
Provided strong evidence of dengue virus in vector pools from domestic/ peri-domestic environments. |
|
|
Study of dengue epidemiology and molecular characterisation of Ae. Aedes aegypti and Ae. albopictus found both vectors had the DENV virus. |
Indicated that newer regions are becoming dengue-endemic; surveillance needs to expand into these regions. |
A study from Table 1 indicates a rising prevalence of Aedes albopictus, marking a species shift that complicates dengue control efforts, as this mosquito thrives in peri-urban and rural environments less affected by indoor spraying measures. In Mizoram, the spread of dengue highlights the importance of decentralised and community-driven surveillance systems. Major cities such as Delhi and Bengaluru continue to report high levels of domestic breeding. Seasonal peaks in vector density and dengue incidence, typically observed between July and August, call for intensified pre-monsoon surveillance. Therefore, these studies highlight the necessity of adaptable control strategies throughout the year.
India, entomological surveillance is mostly reactive, as it is under-prioritised and primarily conducted in response to disease outbreaks or climatic disasters such as floods.
A major technical limitation is that there is no unified nationwide entomological data platform yet. Interviews with state-level experts and senior bureaucrats suggest that human resource deficits include shortages of trained entomologists because of contractual hiring and low incentives under the state health departments. Together, these issues result in fragmented data, delayed responses, and missed opportunities for prediction and early intervention. In India, entomological surveillance is mostly reactive, as it is under-prioritised and primarily conducted in response to disease outbreaks or climatic disasters such as floods.
Strengthening India’s entomological surveillance for dengue requires coordinated systemic reforms and operational modernisation. At the policy level, integration among the NCVBDC, state health departments, local health systems, and municipal bodies must be institutionalised through regular meetings, joint monitoring cells, and the creation of a unified national platform for entering entomological data, ensuring real-time data sharing and standardisation across states. Since in IHIP (part of IDSP), only the data of dengue cases is submitted. Dedicated funding and permanent entomologist posts within health departments are essential to overcome contractual workforce instability. Moreover, policy emphasis should shift toward sustained, year-round surveillance rather than outbreak-driven responses, by including rural and peri-urban zones.
Developing a nation-wide data platform for data sharing of indices of entomological surveillance is the need of the hour.
At the operational level, local capacity building through regular training on advanced surveillance tools, insecticide resistance testing, and molecular xenomonitoring should be prioritised. Ovitraps combined with IoT(Internet of Things), which has an accuracy rate of 97.79 percent can also be used to optimise resources as it eliminates the usage of trained personnel or laboratory facilities. Collaborative initiatives (such as in the Philippines) should be undertaken to employ drone and Artificial Intelligence (AI) technologies for aerial surveys and geospatial analysis, spraying in breeding sites (especially in inaccessible terrain), and monitoring of high-risk breeding water bodies. Routine scheduling of pre-monsoon larval surveillance (January-May) should be ensured, as Aedes eggs can survive desiccation. Surveillance should be carried out weekly or biweekly across high, medium, and low-priority zones since vector populations can rebound quickly in warm months. Monitoring insecticide resistance and evidence-based fogging are required for effective mosquito population control. Developing and scaling self-sexing Aedes strains for biological vector control can effectively suppress wild mosquito populations by up to 96 percent in Brazil. Community-led source reduction (such as in Puducherry) can help strengthen preventive action. Implementation of integrated surveillance systems which combine entomological and epidemiological data, similar to VITEC of Brazil. Developing a nation-wide data platform for data sharing of indices of entomological surveillance is the need of the hour. A unified national action is urgently needed to modernise and sustain entomological surveillance through integrated policy coordination, technological innovation, and community-driven prevention, ensuring proactive dengue control across India.
Damini Bisen is an Intern at the Observer Research Foundation
The views expressed above belong to the author(s). ORF research and analyses now available on Telegram! Click here to access our curated content — blogs, longforms and interviews.
Damini Bisen is an Intern under the Health Initiative, Observer Research Foundation, New Delhi ...
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