El Niño 2026: When a Climate Phenomenon Becomes a Public Health Emergency

Abstract

El Niño is a recurring climate phenomenon whose effects extend beyond oceanic and atmospheric systems to influence population health. In 2026, the event is expected to strengthen through the end of the year, increasing risks of extreme heat, drought and flooding. These climatic changes can alter vector ecology, water availability, food production and healthcare access, thereby affecting the risk of vector-borne and waterborne diseases, malnutrition and heat-related illness. Evidence indicates that El Niño can influence dengue and malaria transmission, although these effects vary according to local climate, ecology, population immunity and health-system capacity. Climate-sensitive disruptions to agriculture may further affect food security and nutritional status, particularly among vulnerable populations. The predictable nature of ENSO provides an opportunity for early action. Integrating meteorological forecasts with disease surveillance, vector control, water-safety measures, nutrition programmes and disaster preparedness can strengthen health-system resilience. A locally calibrated, One Health approach is therefore essential to translate climate information into timely public-health action