El Nino is changing India’s health risks — here’s what WHO is warning about

The World Health Organisation (WHO) has warned of heightened health risks linked to the intensifying El Nino climate phenomenon, with shifting weather patterns potentially fuelling mosquito-borne diseases such as dengue and malaria while increasing exposure to extreme heat.

The warning comes as parts of India continue to report a rise in vector-borne illnesses. In Delhi, municipal data showed 90 new dengue cases in August, the highest monthly count recorded this year, taking the seasonal tally to 311. Malaria cases also rose sharply, from 17 in July to 53 in August.

Why El Nino matters for disease spread

El Nino is a climate pattern caused by periodic warming of surface waters in the central and eastern Pacific Ocean. Its effects can alter weather conditions in different parts of the world.

In India, irregular rainfall, prolonged dry spells and higher temperatures can create conditions that favour mosquito breeding. Water left behind after sudden downpours can collect in containers, drains, construction sites and air coolers, providing breeding grounds for mosquitoes that transmit dengue.

Higher temperatures can also influence the development of dengue virus inside mosquitoes.

Anjal Prakash, Clinical Associate Professor (Research) and Research Director at the Bharti Institute of Public Policy and Regional Climate Adaptation Specialist, was quoted as saying by NDTV, "El Nino isn't just elevating regional temperatures; it is destabilising our seasonal vector baselines. When urban centres experience unseasonal humidity mixed with prolonged thermal spikes, the biological replication rate of the vector speeds up significantly.

Mosquitoes bite more frequently, and the viral incubation period drops. In heavily populated Indian metros, a two-degree uptick in average temperature transforms localised stagnant pools into rapid breeding zones for vector outbreaks."

Dengue, malaria cases rise in Delhi

Delhi's August dengue count was the highest monthly figure of the year, according to the municipal data cited. The city's malaria cases also more than tripled in August compared with July, taking the annual total to 119 across municipal zones.

The report also highlights increased vector surveillance in Maharashtra and southern urban centres amid concerns over stagnant rainwater, humidity and changing weather conditions.

Heat adds another health risk

The changing weather pattern could also increase the risk of heat exhaustion, dehydration and heatstroke. Outdoor workers, including daily-wage labourers and street vendors, may face greater exposure during periods of elevated temperatures.

Heatstroke can cause confusion, dizziness, a rapid pulse, severe muscle cramps and very high body temperature. Dengue, meanwhile, typically causes high fever, intense muscle and joint pain, pain behind the eyes, nausea and skin rashes.

How to reduce the risks

Households can reduce mosquito breeding by emptying, scrubbing and drying water containers, cooler trays and flowerpot drip pans regularly. Using mosquito repellents, window screens and full-sleeved clothing can also reduce mosquito exposure.

People should maintain adequate fluid intake, avoid strenuous outdoor activity during peak afternoon heat and report stagnant water, overflowing tanks and uncollected waste to local authorities.

With changing weather potentially affecting both mosquito activity and heat exposure, health authorities are urging greater attention to prevention and early recognition of illness.