A recent study titled ‘Dengue Dynamics, Predictions, and Future Increase under Changing Monsoon Climate in India’ has projected a 13% rise in dengue-related mortality in Pune by 2040.
The study highlights the complex relationship between climate and dengue in India, warning that without timely intervention, rising temperatures and erratic monsoon patterns could increase dengue deaths by 13% by 2040 and by 25 to 40% by mid-century (2040 to 2060).
The study – conducted by scientists from the Indian Institute of Tropical Meteorology (IITM); University of Maryland, USA; Savitribai Phule Pune University; University of Nottingham, UK; Government of Maharashtra; and the Natural Research Development Corporation (NRDC) – was published in ‘Scientific Reports’ on January 21.
The study explores how temperature, rainfall, and humidity drive dengue dynamics in Pune, one of India’s dengue hotspots. It reveals that a combination of temperatures above 27°C; moderate and evenly distributed rainfall; and humidity levels between 60% and 78% during the monsoon season (June to September) significantly increases dengue cases and deaths.
However, heavy rainfall exceeding 150 mm in a week helps reduce dengue prevalence by flushing out mosquito eggs and larvae.
The researchers also observed that lower variability in monsoon patterns — characterised by fewer active (wet) and break (dry) phases — is linked to higher dengue cases. Conversely, higher variability in rainfall is associated with fewer dengue cases. The findings emphasise that it is not the cumulative rainfall but the distribution pattern that critically influences dengue transmission in Pune. While the findings are specific to Pune, they underline the need for region-specific assessment of the relationship between climate and dengue based on local health data.
Projected rise in dengue mortality
The study projects further increase in temperature and humidity over India, with more erratic monsoon rainfall interspersed with heavy-to-extreme showers. While heavy rain can reduce mosquito larvae, the overall warming trend is expected to dominate future changes in dengue dynamics.
Under low-to-high fossil fuel emission scenarios, Pune is expected to see an average temperature rise of 1.2 to 3.5 degrees Celsius by the end of the century. This could lead to a 13% rise in dengue mortality by 2040, corresponding to global warming crossing 1.5 degrees Celsius.
Mortality rates may further increase to 25 to 40% by mid-century (2040 to 2060) at 2 degrees Celsius global warming under moderate-to-high emissions. The researchers cautioned that these projections are based on climatic conditions conducive to dengue transmission and do not account for socio-economic factors that may also influence the spread of the disease.
Developing an early warning system
Dr Roxy Koll, lead scientist from IITM, said, “We developed this study and an early warning system using health data shared by Pune’s health department. We approached other states like Kerala but the lack of cooperation from their health departments hindered similar efforts. With health data and meteorological inputs from the India Meteorological Department (IMD), we can design customised early warning systems for climate-sensitive diseases such as dengue, malaria, and chikungunya. Cooperation from health departments is critical to saving lives.”
The team developed an artificial intelligence/machine learning (AI/ML) model that incorporates key climatic predictors such as temperature, rainfall and humidity to forecast potential dengue outbreaks. The model can predict outbreaks more than two months in advance with reasonable accuracy, giving local administration sufficient time to improve preparedness and response strategies.
Policy implications and the way forward
Effective early warning systems for dengue rely heavily on comprehensive health data collection and sharing. States like Kerala, Maharashtra, West Bengal, Karnataka, Tamil Nadu, Gujarat, Punjab, Haryana, Andhra Pradesh, Telangana, Rajasthan, and Uttar Pradesh, which bear a significant dengue burden, can benefit greatly from such advanced systems.
Dr Sophia Yacob, IITM scientist and coauthor of the study, said, “These insights can guide policymakers in planning targeted interventions and allocating resources to manage climate-sensitive diseases. The model we developed can be adapted to other regions, offering a valuable tool for managing diseases like dengue.”
The study underscores the importance of timely, data-driven intervention to mitigate the public health impact of climate change and save lives.
