Climate Change and Dengue, a Growing Public Health Crisis

Impending climate change spells disaster for mankind, with our species pillaging and decimating every corner of the earth like some sort of bipedal locust. In other news, mosquitoes are running amok, spreading dengue, among other diseases, among populations that are most vulnerable.

Dengue is a viral infection transmitted by the Aedes mosquito, especially Aedes aegypti, which thrives in warm, humid environments. Traditionally considered a seasonal disease peaking during and after the rainy season, it has today morphed into a year-round risk in many parts of India.

The World Health Organisation has already labelled dengue as one of the top ten global public health threats—one that is being made worse by climate change.

You see, the link between a boiling planet and the increase in vector-borne diseases like dengue is no longer theoretical. Higher temperatures facilitate mosquito breeding cycles and virus replication, while less-than-regular rainfall creates more stagnant water, making it an ideal breeding ground for mosquitoes.

This blog will examine the link between climate change and dengue, with a special focus on how India, a country highly susceptible to both, is responding via vaccines, public health campaigns, and climate-resistant policies.

Dengue is a mosquito-borne viral infection caused by four closely related viruses, DENV-1, DENV-2, DENV-3 and DENV-4. One demarcated as a tropical disease restricted to some geographies only, dengue has become endemic in more than 100 nations, affecting millions yearly.

Blame the female Aedes mosquitoes. Specifically the Aedes aegypti mosquitoes. They are the primary carrier of this deadly disease. They are active mostly during the early morning and late afternoon. Another species, the Aedes albopictus also partakes in transmission in some regions.

Dengue has some really distinct symptoms. Like,

• Really high fever

• Bad headache (Especially behind the eyes)

• Muscle and joint pain (nicknamed “breakbone fever”)

• Nausea and vomiting

• Skin rash

• Fatigue and weakness

• Mild bleeding (nosebleeds, gum bleeding or easy bruising)

In some cases, dengue can escalate into severe dengue (earlier known as dengue hemorrhagic fever or dengue shock syndrome), which might include

• Severe bleeding

• Drop in blood pressure

• Organ failure

• Death (especially if untreated)

Sadly, there isn’t any specific antiviral treatment for dengue. Patients are asked to rest, remain hydrated and take paracetamol for fever and pain. Aspirin and NSAIDS must be avoided because they might cause bleeding. Many cases might require hospitalisation and intensive monitoring.

Early detection and comprehensive medical care can greatly lower fatality rates. However, prevention remains the most useful defense - especially via mosquito control and community awareness.

The ecology of disease-carrying mosquitoes is closely tied to the environment, and climate change is quickly changing that environment in ways conducive to the spread of dengue.

With increasing global temperatures, changing rainfall patterns and rising humidity levels, mosquito populations are growing, becoming hardier and invading new areas.

Rising Temperatures and Breeding Cycles

Increased ambient temperatures exacerbate the life cycle of the Aedes mosquito. Warmer conditions bring down the time needed for larvae to become adult mosquitoes, thereby increasing the frequency of breeding and boosting mosquito populations.

Rainfall and Stagnant Water

Irregular and intense rainfall - another side-effect of climate change, often results in waterlogging and the accumulation of stagnant water in urban and semi-urban environments.

These pools of water are ideal breeding grounds for Aedes mosquitoes. Sadly, drought conditions can also increase the risk, as households usually store water in open containers during water shortages, creating breeding sites.

Changing Humidity Patterns

The Aedes mosquito thrives in warm and humid conditions. Climate change-induced shifts in humidity levels have been shown to increase mosquito survival rates and biting activity.

Increased humidity prolongs mosquito lifespans, permitting more time for them to transmit the virus to different hosts.

Urban Heat Islands and Mosquito Density

Cities are becoming hotter than their surrounding rural areas due to the urban heat island effect, which is caused by concrete surfaces, a paucity of vegetation, and heat-trapping infrastructure.

This localised warming creates an ideal microclimate for Aedes mosquitoes, especially in densely populated, poorly planned urban areas with poor waste management and water storage practices.

Geographical Expansion of Mosquito Habitats

What is most alarming is that climate change is pushing mosquito populations into new geographic territories, including hill stations and cooler regions that were earlier inhospitable to them.

States such as Himachal Pradesh and Uttarakhand in India, which almost never reported dengue in the past, have begun experiencing seasonal spikes.

Gone are the days when dengue was a seasonal nuisance, a speciality of tropical belts—it is quickly becoming a global public health emergency.

According to the World Health Organisation, more than 5 million dengue cases were reported globally in 2023, marking one of the highest annual figures on record. The disease now impacts more than 129 countries, with outbreaks becoming more severe and frequent.

India remains one of the countries worst affected by dengue. In 2023 alone, the nation reported more than 200,000 confirmed cases—a number that many health experts believe is a gross underestimate due to underreporting and limited surveillance in certain regions.

The past two decades have experienced a worrying trend - annual case counts have increased sharply, with outbreaks going beyond traditional hotspots.

This surge is not a short-term spike. According to historical data, a clear picture of escalation is apparent - in the early 2000s, India averaged fewer than 60,000 dengue cases annually. By the 2010s, that number had surpassed 100,000 each year.

Since 2020, the country has witnessed repeated spikes, with more states declaring health alerts and emergency responses.

Climate change is also changing the seasonal dynamics of dengue transmission. While the disease traditionally peaked in the post-monsoon months from September to November, many regions now report an earlier onset and extended transmission window.

Warmer winters, together with erratic rainfall and poor urban drainage, have created the ideal breeding conditions for mosquitoes, round the year.

As dengue cases increase across the country and the disease breaches new boundaries, India is increasing its response via a multipronged strategy, ranging from vaccine development to community-level mosquito control, and the integration of climate policy into public health frameworks.

On the vaccination front, India is making good progress. There is no licensed dengue vaccine currently available for mass public use in India with trials actively underway.

The Japanese pharmaceutical company Takeda has partnered with Hyderabad-based Biological E to introduce Qdenga, a tetravalent dengue vaccine, into the Indian market, pending regulatory approval.

Meanwhile, the Indian Council of Medical Research (ICMR) and Panacea Biotec are collaborating on the indigenous DengiAll vaccine, which is right now in the clinical trial stage. Such efforts hold promise for a more robust defence against dengue in the near future.

Vector control remains a central pillar of India’s dengue response. At the grassroots level, Accredited Social Health Activists (ASHAS) are being trained to educate communities about mosquito breeding prevention and early symptom identification.

Village-level sanitation drives are increasingly focused on eliminating stagnant water sources, where Aedes mosquitoes thrive.

Strengthening health infrastructure is also a major focus. The Integrated Disease Surveillance Programme (IDSP) plays an important role in tracking and replying to dengue outbreaks, picking up real-time data from the length and breadth of India.

Also, district-level diagnostic laboratories have been erected to facilitate faster and more accurate testing, reducing delays in treatment and outbreak reporting.

India is also one of the pioneering countries actively looking to align climate action with public health preparedness.

The Ministry of Health and Family Welfare has launched the National Action Plan on Climate Change and Human Health (NAPCCHH) which draws out strategies for climate-resilient healthcare infrastructure, early warning systems and capacity building at the local level.

Public awareness campaigns are another important component of the national response. The government, in conjunction with NGOS and local bodies, regularly runs dengue prevention campaigns - especially during peak season - through television, radio and social media.

These campaigns concentrate on simple yet effective measures like using mosquito nets, donning long sleeves and constantly checking for stagnant water surrounding homes.

India’s response is holistic and ever-changing, the sheer complexity of the dengue challenge - exacerbated by climate change, is a clarion call for deeper investments, faster vaccine deployment and superior inter-sectoral coordination to keep public health safe in the coming years.

As climate change carries on, the constant threat of dengue fever is looming more and more. One of the biggest challenges is the scarcity of dengue vaccines.

Even though recent developments like Takeda’s Qdenga have shown potential, widespread public rollout in countries like India is still a far-fetched idea, depending on trials, regulatory approvals and logistical frameworks for distribution.

Making this worse is the delicate state of healthcare infrastructure in many rural and semi-urban regions.

These places are often bereft of diagnostic facilities, trained personnel, and surveillance systems needed for timely identification and response to dengue outbreaks.

When cases go up, especially during the rainy season, these under-resourced systems can quickly get overwhelmed.

Climate change has compounded this thanks to erratic rainfall patterns and increasing instances of urban flooding - creating perfect breeding grounds for Aedes mosquitoes, the biggest carrier of dengue.

Water accumulation in construction zones, blocked drains, and unmanaged waste have made even urban centres quite vulnerable.

From a system perspective, India’s public health planning has been slow to completely integrate climate adaptation measures. Projections under different climate models show us that dengue will spread to previously unaffected cooler regions, including parts of northern India and hill states.

This geographical shift will probably bring about year-round transmission cycles, longer outbreaks and an increased disease burden.

Addressing such challenges needs more than isolated health campaigns. It warrants robust cross-section collaboration between public health departments, urban planners, sanitation bodies and climate scientists.

Only a holistic strategy can make India effectively mitigate the dual threat of climate change and dengue.

With dengue cases increasing, climate change getting worse, and the conditions for mosquito breeding, individual and community-level action are more vital than ever. Prevention remains the most effective disease defence, especially when there are no vaccines.

On a personal level, protective measures can greatly bring down your risk of being bitten by an Aedes mosquito. Such mosquitoes are most active during early morning and late afternoon, so it is vital to don long-sleeved clothing and full-length pants during such hours.

Another step? Eliminating mosquito breeding grounds near your home. Since Aedes mosquitoes lay eggs in clean, stagnant water, it is vital to regularly empty and scrub containers like flowerpots, water tanks, coolers and birdbaths.

Make sure drains are unclogged and gutters are cleaned regularly. Installing mesh screens on windows and doors can also stop mosquitoes from invading living spaces.

Community participation is very important. Dengue control cannot be achieved via individual action. Organise or support neighbourhood cleanliness drives, and report stagnant water or mosquito-infested areas to local authorities.

Getting schools, resident welfare associations and local health volunteers can amplify the impact of such efforts.

Also, staying informed is important. Keep an eye on updates from local health departments during outbreak seasons, and don’t ignore early symptoms like rash, body aches or fever. Early diagnosis can prevent complications and also stop the spread of the virus.

By ensuring proactive informed steps, individuals and communities can together craft stronger resilience against the growing threat of dengue in a warming world.

The ever burgeoning link between climate change and the increasing incidence of dengue is no longer a distant projection - it is today’s reality.

Warmer temperatures, erratic rainfall and expanding mosquito habitats have created the perfect storm for increased and more prolonged dengue outbreaks, especially in tropical regions like India.

Finally, tackling dengue in a changing climate is not just a health issue - it is a climate action. Adaptation and mitigation strategies must come together with public health responses.

By putting money into sustainable urban planning, improving waste management and crafting climate-resilient health systems, we can bring down mosquito breeding and curb the risk of vector-borne diseases.

Climate action today - disease prevention tomorrow - will protect our planet and public health.

Q. How is climate change linked to the rise in dengue cases?

A. Rising temperatures, erratic rainfall, and higher humidity levels create ideal conditions for Aedes mosquitoes to breed and spread, leading to longer and more intense dengue seasons.

Q. Are dengue outbreaks getting worse in India?

A. Yes. India has seen a significant rise in dengue cases over the past decade, with outbreaks occurring more frequently and spreading to new regions, including parts of North and Northeast India that were previously unaffected.

Q. Is there a vaccine for dengue in India?

A. Vaccine development is underway. Qdenga (by Takeda) has been approved in several countries, and India is conducting trials with DengiAll (ICMR + Panacea Biotec). However, widespread access is still a few years away.

Q. What role do urban areas play in the spread of dengue?

A. Urban heat islands, poor waste disposal, and water stagnation from unplanned construction and flooding provide perfect breeding grounds for dengue-carrying mosquitoes in cities and towns.

Q. What can I do to protect myself from dengue?

A. Use mosquito repellents, wear long clothing, install screens and nets, and eliminate stagnant water around your home.