Rising temperatures, longer monsoons make dengue a persistent threat in South Asia; Tips to tackle this growing threat | Health

In recent years, the term “seasonal” has lost its relevance when discussing diseases such as dengue fever because dengue outbreaks, once thought to be limited to certain times of the year, have now become a year-round nightmare, especially in regions such as South Asia, due to climate change. Longer monsoon seasons, rising temperatures and changing mosquito behaviour have upended the traditional understanding of dengue being seasonal, making it a threat that knows no boundaries.

In an interview with HT Lifestyle, Prasad Phadke, founder and CEO of Eco Biotraps and Sushanta Kumar Ghosh, scientific advisor and alumnus of ICMR-National Institute of Malaria Research in Bangalore, revealed, “The gravity of the situation became clearly evident in November 2023 when Bangladesh faced its worst dengue outbreak. Hospitals were overwhelmed with patients and the death toll kept rising. What made this outbreak particularly dangerous was that it broke away from the expected seasonal pattern.”

Historically, dengue was associated with the monsoon season, usually between June and September, when stagnant water provided ideal breeding grounds for dengue. Aedes Mosquitoes are the carriers of the dengue virus. However, the scenario has changed and these mosquitoes are now moving north and more European countries are at risk of dengue fever.

According to Prasad Phadke and Sushant Kumar Ghosh, climate change has disrupted traditional weather patterns, leading to longer and more intense monsoon rains across South Asia. They shared, “In July 2023, the monsoon was 13 percent above the long-term average, further exacerbating the dengue crisis. While floods wreaked havoc in many parts of India, some districts also witnessed unexpected outbreaks of mosquito-borne diseases such as dengue fever. In 2022, Pakistan has also faced similar challenges, indicating a regional crisis of unprecedented proportions.”

The core problem lies in the changing behaviour of Aedes mosquitoes, which have adapted to the new environmental conditions brought about by global warming. Prasad Phadke and Sushanta Kumar Ghosh explained, “These mosquitoes no longer inhabit the traditional breeding grounds of clean water during the monsoon season. Instead, they have displayed a remarkable ability to breed even in salty water. This new resilience renders conventional insecticides ineffective, as mosquitoes have developed resistance over time. Moreover, the concept of “seasonality” has lost its meaning as temperatures are rising and rainfall patterns have become erratic. Dengue is no longer restricted to a specific time frame but has become a constant threat throughout the year. As people find themselves exposed to mosquitoes for longer periods of time, the likelihood of contracting dengue increases, leading to a public health crisis.”

Tackling this emerging threat requires a multi-pronged approach that acknowledges the interconnected nature of climate change and disease dynamics. Prasad Phadke and Sushanta Kumar Ghosh suggest –

• First, there is an urgent need for better surveillance and monitoring systems to quickly detect and respond to outbreaks. Timely detection can help reduce the spread of the virus and reduce the burden on healthcare systems.
• Second, efforts to combat mosquito-borne diseases must evolve to adapt to changing mosquito behaviour and environmental conditions. This includes research into alternative vector control methods and innovative approaches to mosquito management.
• In addition, public awareness campaigns play a vital role in empowering communities to take preventive measures against dengue. Simple measures such as removing stagnant water, using mosquito nets and wearing protective clothing can significantly reduce the risk of infection.
• On a broader level, mitigating climate change requires concerted global action to address the root cause of the problem. By reducing greenhouse gas emissions and investing in sustainable practices, we can limit the extent of global warming and reduce its impact on public health.

The experts stressed, “Due to climate change, it is no longer appropriate to consider dengue a seasonal disease. The convergence of environmental factors has transformed dengue into a year-round threat, posing serious challenges to public health systems in affected areas. To confront this crisis, we must adopt a comprehensive approach that includes surveillance, vector control, public awareness, and climate mitigation efforts. Only through collective action can we stem the dengue wave and protect vulnerable communities from its devastating impact.”