Health News / El Niño in India: WHO Warns of Dengue, Malaria and Heat Illness Risks

Geneva, Sep 12: The World Health Organization (WHO) has raised concerns about the potential health impact of changing weather patterns associated with the El Niño climate phenomenon. India has been placed in the “high to very high” risk category amid concerns that extreme heat, unseasonal weather changes and irregular rainfall could increase the spread of mosquito-borne diseases and heat-related illnesses.

The changing climate conditions are creating a dual public health challenge across parts of South Asia. On one hand, warmer temperatures and irregular rainfall can create favourable conditions for mosquitoes that transmit diseases such as dengue and malaria. On the other, prolonged periods of extreme heat can increase the risk of dehydration, heat exhaustion and heatstroke.

The concern comes as several Indian cities report an increase in vector-borne diseases.

Dengue and Malaria Cases Rise In Delhi

Delhi has reported a noticeable increase in mosquito-borne diseases.

As per the municipal data, the national capital recorded 90 new dengue cases in August, the highest monthly tally reported so far this year. The number of dengue cases during the season reached 311.

Malaria cases also increased sharply during the same period. Cases rose from 17 in July to 53 in August, highlighting the growing challenge posed by mosquito-borne infections.

The combination of rising mosquito activity, changing rainfall patterns and fluctuating temperatures could put additional pressure on public health systems in Delhi and other urban centres across northern and central India.

How Does El Niño Affect Dengue and Heat-Related Illnesses?

El Niño occurs when surface waters in the central and eastern Pacific Ocean become unusually warm, disrupting weather patterns around the world.

In India, El Niño-related changes can contribute to unusual temperature patterns, prolonged dry spells and irregular rainfall. These conditions can influence both mosquito populations and the risk of heat-related illnesses.

Warmer Temperatures Can Accelerate Mosquito Development

Temperature plays an important role in the life cycle of mosquitoes and the development of viruses inside them.

Higher temperatures can accelerate the development of dengue virus inside Aedes aegypti mosquitoes, potentially reducing the time required before an infected mosquito can transmit the virus.

At the same time, sudden rainfall can leave stagnant water in places such as drains, construction sites, discarded containers, air coolers and flowerpot trays. These water-filled areas can become breeding grounds for mosquitoes.

Extreme Heat Can Increase the Risk of Heatstroke

Periods of unusually high temperatures can increase the risk of dehydration, heat exhaustion and heatstroke.

People who work outdoors, older adults, young children, pregnant women and individuals with existing cardiovascular, respiratory or kidney conditions may be particularly vulnerable during periods of extreme heat.

Dengue and Malaria Risks Across India
The health impact of changing weather conditions is not limited to Delhi.

• Dengue: Delhi recorded 311 cases through late August, including 90 cases during August. Other urban centres, including cities in Maharashtra and southern India, are also strengthening mosquito surveillance.

• Malaria: Delhi's malaria cases increased from 17 in July to 53 in August, taking the annual total to 119 cases across municipal zones.

• Heat-related illness: Outdoor workers, daily-wage labourers and street vendors may face increased risks of dehydration, heat exhaustion and heatstroke during periods of elevated temperatures.

• Vulnerable groups: Extreme heat can place additional stress on healthcare systems and may increase health risks for pregnant women, newborns, children and people with pre-existing medical conditions.

Common Symptoms of Heat Exhaustion and Heatstroke

Heat exhaustion may cause:

• Heavy sweating
• Weakness and dizziness
• Muscle cramps
• Headache
• Nausea
• Rapid pulse
• Dehydration

Heatstroke is more serious and can cause very high body temperature, confusion, altered mental status or loss of consciousness. Heatstroke is a medical emergency and requires immediate medical attention.

Common Symptoms of Dengue

Dengue may cause:

• High fever
• Severe headache
• Pain behind the eyes
• Intense muscle and joint pain
• Nausea or vomiting
• Skin rash
• Weakness and fatigue

Some patients can develop warning signs or complications as the illness progresses. Anyone experiencing persistent high fever, severe abdominal pain, repeated vomiting, bleeding, extreme weakness or other concerning symptoms should seek medical care promptly.

How to Protect Yourself From Dengue and Heat Illness

With mosquito-borne diseases and extreme heat potentially occurring together, households can take several preventive measures.

1. Follow a Weekly “Dry Day”

Empty, clean and dry water containers, air-cooler trays, flowerpot saucers and other potential mosquito-breeding sites at least once a week.

2. Prevent Mosquito Bites

Use appropriate mosquito repellents, install screens on doors and windows and wear loose-fitting, light-coloured clothing that covers the arms and legs.

3. Stay Hydrated

Drink adequate fluids throughout the day. Oral rehydration solutions and electrolyte-containing drinks can help replace fluids and salts when needed.

Avoid strenuous outdoor activity during the hottest part of the day, particularly during periods of extreme heat.

4. Keep Your Surroundings Clean

Do not allow water to accumulate around homes, workplaces or construction sites. Report stagnant water, blocked drains, overflowing tanks and uncollected waste to local authorities.

Also Read: Odisha Ethylene Spray Fruit Ripener Raids: Why Traders Take the Risk and How Consumers Can Stay Safe

Why Climate-Responsive Healthcare Is Becoming More Important

The combination of changing rainfall patterns, rising temperatures and mosquito activity highlights the growing need for climate-responsive public health measures in India.

As weather patterns become less predictable, communities may face overlapping risks from dengue, malaria and heat-related illnesses. Stronger mosquito surveillance, early-warning systems, heat-health action plans and timely access to medical care can help reduce the impact of these seasonal health threats.