Rising temperatures, longer monsoons make dengue constant danger in South Asia; tips to address this evolving threat

In recent years, the term “seasonal” has lost its relevance when discussing diseases like dengue fever because once thought to be confined to specific times of the year, dengue outbreaks have now become a year-round nightmare, especially in regions like South Asia courtesy the culprit - climate change. The convergence of longer monsoon seasons, rising temperatures and altered mosquito behaviours has shattered the traditional understanding of dengue's seasonality, transforming it into a perpetual threat that knows no boundaries.

In an interview with HT Lifestyle, Prasad Phadke, Founder and CEO at Eco BioTraps and Susanta Kumar Ghosh, Scientific Advisor and Former ICMR-National Institute of Malaria Research in Bangalore, revealed, “The severity of the situation became starkly apparent in November 2023 when Bangladesh faced its worst-ever dengue outbreak. Hospitals overflowed with patients and the death toll continued to rise. What made this outbreak particularly alarming was the deviation from the expected seasonal pattern.”

Historically, dengue was associated with the monsoon season, typically between June and September, when stagnant water provided the perfect breeding ground for Aedes mosquitoes, the carriers of the dengue virus. However, the landscape has shifted and these mosquitoes are now moving towards the north and more European countries are under the threat of dengue fever.

According to Prasad Phadke and Susanta 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, exacerbating the dengue crisis. While flooding ravaged many parts of India, certain districts experienced unexpected outbreaks of mosquito-borne diseases like dengue fever. In 2022, Pakistan, too, has faced similar challenges, indicating a regional crisis of unprecedented proportions.”

The underlying issue lies in the changing behaviour of Aedes mosquitoes, which have adapted to new environmental conditions brought about by global warming. Prasad Phadke and Susanta Kumar Ghosh explained, “These mosquitoes no longer adhere to the conventional breeding grounds of clean water during the monsoon season. Instead, they have demonstrated a remarkable ability to breed even in saline water. This newfound resilience renders conventional insecticides ineffective, as the mosquitoes have developed resistance over time. Moreover, the concept of “seasonality” has lost its meaning as temperatures soar and rainfall patterns become erratic. Dengue is no longer confined to a specific time frame but has become a constant threat, lurking throughout the year. As people find themselves exposed to mosquitoes for longer durations, the likelihood of contracting dengue multiplies, amplifying the public health crisis.”

Addressing this evolving threat requires a multifaceted approach that acknowledges the intertwined nature of climate change and disease dynamics. Prasad Phadke and Susanta Kumar Ghosh suggested -

• First, there is an urgent need for enhanced surveillance and monitoring systems to detect and respond to outbreaks promptly. Early detection can help mitigate the spread of the virus and alleviate the burden on healthcare systems.
• Secondly, efforts to combat mosquito-borne diseases must evolve to keep pace with changing mosquito behaviors and environmental conditions. This includes research into alternative vector control methods and innovative approaches to mosquito management.
• Additionally, public awareness campaigns play a crucial role in empowering communities to take preventive measures against dengue. Simple actions such as eliminating stagnant water, using mosquito nets, and wearing protective clothing can significantly reduce the risk of infection.
• On a broader scale, addressing the root cause of the problem requires concerted global action to mitigate climate change. By reducing greenhouse gas emissions and investing in sustainable practices, we can limit the extent of global warming and mitigate its impact on public health.

The experts asserted, “The notion of dengue as a seasonal disease is no longer tenable in the face of climate change. The convergence of environmental factors has transformed dengue into a year-round threat, posing significant challenges to public health systems in affected regions. To confront this crisis, we must adopt a comprehensive approach that encompasses surveillance, vector control, public awareness, and climate mitigation efforts. Only through collective action can we hope to stem the tide of dengue and protect vulnerable communities from its devastating impact.”