Image Source: Getty
Introduction
In 2023, a 12-year-old boy from Nagaland died of dengue—a disease that had not been reported in the state until 2015. This is not an isolated case but is part of a broader trend: climate change is reshaping the global spread of vector-borne diseases (VBDs) like dengue, which is transmitted by mosquitoes. A growing body of research shows that higher temperatures boost mosquito reproduction, speed up larval growth, and reduce the time it takes for mosquitoes to reach maturity. It is also been noted that adult mosquitoes bite more frequently at warmer temperatures. The dengue virus replicates faster in their bodies, making them capable of infecting new hosts quickly. A warmer climate also expands the range of mosquitoes into previously cooler, non-endemic regions. Areas such as Shimla, Northern Himachal Pradesh, and Jammu and Kashmir have reported an increase in cases of dengue. High humidity supports their survival and egg development, while excess rainfall and flooding create stagnant water pools ideal for breeding. Even drought can contribute to mosquito populations, as stored water in containers provides additional breeding sites.
A growing body of research shows that higher temperatures boost mosquito reproduction, speed up larval growth, and reduce the time it takes for mosquitoes to reach maturity.
The World Health Organization (WHO) estimates that climate change could expose an additional 4.7 billion people to dengue globally by the end of this century. India is already witnessing the early impacts. In the country, the number of reported dengue cases has seen a dramatic increase, rising from 28,066 cases in 2010 to a staggering 289,235 cases in 2023. Table 1 looks at the number of cases and deaths in the country since 2019. This increase can be partially attributed to climatic shifts. The rise in disease incidence not only strains the healthcare system but also imposes a heavy socio-economic burden. Addressing the rise in VBDs is not only a health priority but also vital for achieving broader development goals such as Universal Health Coverage and Sustainable Development Goals (SDGs). Effective strategies are urgently needed to protect vulnerable populations.
Source: National Centre for Vector-Borne Diseases Control
Recommendations
India needs a comprehensive strategy to combat dengue and other climate-sensitive VBDs. This strategy should draw from various international models, past public health campaigns, and region-specific interventions.
1. Short-term efforts
A. Using insecticide-treated materials
For dengue, one of the most effective strategies to control its spread is to use insecticide-treated materials (ITMs) to protect homes and individuals from mosquito bites. A study conducted in Mexico studied the effectiveness of ITMs. It found that insecticide-treated screens permanently affixed to windows and doors significantly reduced mosquito infestations in treated houses. Another promising intervention involves using insecticide-treated water container covers when storing water, especially during extreme calamities. While ITMs are recommended and are part of India’s vector control strategies, their usage is irregular. An increase in targeted outreach, culturally and socially relevant messaging, and regular monitoring can help enhance the effectiveness of ITMs in combating all vector-borne diseases.
An increase in targeted outreach, culturally and socially relevant messaging, and regular monitoring can help enhance the effectiveness of ITMs in combating all vector-borne diseases.
B. Implementing biocontrol strategies
Given the unintended side effects of insecticides, such as biomagnification, harm to non-target species and insecticide resistance, alternate remedies such as biocontrol can be attempted. One of the most popular biocontrol strategies to control dengue is to utilise selective fish species such as Gambusia affinis into stagnant water bodies. The fish feeds on mosquito larvae, thereby restricting the number of adult mosquitos. This method is particularly suited for regions where artificial water storage is in vogue and chemical insecticides may not be regularly utilised. This specific biocontrol measure has already been attempted in many parts of the country including Andhra Pradesh, and it might be useful now to extend it in the remaining parts as well. Although biocontrol can lead to the possibility of disrupting local ecosystems, it remains an effective tool for managing mosquitos in household tanks or ponds.
C. Strengthening public-private partnerships
Public-private partnerships can be effectively used to control the high incidence of dengue. A possible programme could involve government authorities collaborating with private businesses in the biocontrol sector to combat mosquito populations in rural and urban water bodies. Appropriate schemes to encourage the sale of low-cost ITMs or to sponsor community clean-up campaigns by local businesses can be launched.
D. Specific initiatives for remote areas
There is an urgent need to check the increasing incidence of dengue in remote areas where the disease is now spreading. In such areas, due to unique challenges such as weaker public health infrastructure, and limited access to healthcare, particularly during peak disease season, health authorities may consider the expansion of mobile health clinics to ensure their constant presence in the region. These mobile health centres could provide rapid diagnostic testing for dengue, distribute insecticide-treated bed nets and water container covers, and educate communities about disease prevention.
Dry days, which are extensively promoted by the government in urban areas, are effective in raising public awareness. For example, in Delhi, municipal workers carry on house inspections to eliminate mosquito breeding sites and ensure proper sanitation. They also impose fines for improper water storage. These proactive measures may be extended to rural and underserved areas so as to prevent them from becoming hotbeds of the disease.
ASHA workers can lead community-based research initiatives, engaging local women and youth groups in data collection, environmental monitoring, and mapping mosquito breeding sites.
Further, telemedicine platforms must be better integrated with local health systems in rural areas to support rural health workers and patients. To enable them to identify early warning signals of dengue outbreaks and to ensure robust reporting, ASHA workers, who are predominantly women and hold strong community trust, may be trained in disease surveillance using mobile health applications. Additionally, ASHA workers can lead community-based research initiatives, engaging local women and youth groups in data collection, environmental monitoring, and mapping mosquito breeding sites. To address potential cultural barriers, local health workers and NGOs should also conduct culturally sensitive outreach to build trust within communities, thereby encouraging the adoption of mosquito control measures.
E. Integrating disease prevention into disaster management plans
Climate change is increasing the frequency of extreme weather events such as floods and cyclones, exacerbating the spread of vector-borne diseases. For instance, floods in Assam and Bihar have historically led to outbreaks of diseases like Japanese Encephalitis (JE). India’s disaster management plans should include specific protocols for disease prevention, particularly in post-disaster situations where stagnant water and debris create ideal conditions for mosquito breeding. This protocol could include pre-disaster actions like mapping high-risk areas for potential mosquito breeding and stocking emergency supplies.
F. Establishing early warning systems
Another crucial component of mitigating risk is the implementation of early warning systems based on climate models. These systems could use rainfall patterns, temperature changes, and humidity levels to predict potential dengue outbreaks. Thus, they will be able to allow public health officials to take proactive measures, such as increasing public awareness or initiating mosquito control programmes, and guiding resource allocation. These systems are also useful for other climate-sensitive diseases.
2. Long-term efforts
A. Adopting Integrated Vector Management (IVM)
Short-term initiatives offer technical solutions, but long-term success requires sustained efforts.
One of the most effective long-term strategies for combating climate-sensitive diseases is to integrate Integrated Vector Management (IVM) principles into the National Disease Programmes. While India’s NVBDCP includes many elements of the IVM, several shortcomings hinder its full effectiveness. IVM encourages collaboration between health, agriculture, urban planning, and environmental agencies to reduce vector breeding sites. In practice, however, there is a lack of synergy between different departments. Local execution of plans is also somewhat inconsistent, especially in remote and underserved areas. The success of IVM within the NVBDCP depends on training local teams to carry out a mix of biological, environmental, and chemical controls, along with encouraging community participation. Capacity-building workshops, similar to those in Kerala, and technical training are essential here. In addition, encouraging region-specific joint action plans can help address the gaps.
Engaging with neighbouring countries like Bangladesh or Sri Lanka could be key to joint regional efforts due to the cross-border impacts of climate change on disease spread.
B. Fostering international collaboration
India can also benefit from participating in global forums to share knowledge and best practices with other countries facing similar challenges. For example, the WHO’s Global Vector Control Response initiative offers a platform to exchange research and strategies. Engaging with neighbouring countries like Bangladesh or Sri Lanka could be key to joint regional efforts due to the cross-border impacts of climate change on disease spread.
Conclusion
Climate change is not a distant threat. It already modifying the epidemiology of vector-borne diseases, and India’s public health response must adapt accordingly. The consequences of failing to act now are severe: lives will be lost, healthcare systems will be overwhelmed, and economic progress will be hindered. IVM, community mobilisation, and public-private partnerships are essential. India must also invest in climate-sensitive health infrastructure, improve disease surveillance systems, and establish early warning mechanisms to stay ahead of future outbreaks. The strategies employed today will determine India’s ability to combat not only dengue but also other climate-sensitive diseases that may emerge in the coming decades.
Abhishree Pandey is a Research Intern at the Observer Research Foundation
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