Anticipating El Niño–related health risks in Latin America and the Caribbean: from climate information to public health preparedness

El Niño is a recurrent mode of tropical Pacific climate variability with major public health implications for Latin America and the Caribbean. Its development is partly driven by the Bjerknes feedback, a coupled ocean–atmosphere process in which weakened equatorial trade winds reduce coastal upwelling and allow warm surface waters to shift eastward. Warming of the central and eastern tropical Pacific can reshape regional rainfall and temperature patterns, increasing the likelihood of floods, droughts, wildfires, food-system disruption, and health-service interruption in locations with established ENSO teleconnections. This narrative review synthesizes evidence on the environmental and health pathways through which El Niño may affect populations in Latin America and the Caribbean. We distinguish evidence directly linking health outcomes to ENSO or Coastal El Niño from evidence derived from floods, droughts, wildfires, and other hydrometeorological disasters without formal attribution to ENSO. The latter is used to characterize plausible health pathways and preparedness needs rather than ENSO-specific causal effects. Potential consequences include immediate mortality and injury, waterborne and vector-borne infections, disruption of chronic disease care, food insecurity, undernutrition, toxic exposures, psychological distress, and prolonged health-system burden. The timing and persistence of these effects are context-dependent; preparedness and response priorities are therefore organized by operational needs rather than fixed post-event intervals. As of August 2026, authoritative forecasts indicated that El Niño was present and strengthening, providing a current illustration of why anticipatory preparedness is necessary while not guaranteeing any specific regional impact. Early warning, flood-risk mapping, water, sanitation, and hygiene interventions, epidemiological and entomological surveillance, continuity of health services, and community-centered risk communication should therefore be adapted to local forecasts, vulnerabilities, and surveillance data.