El Nino: What is it and how does it affect health?

Several parts of the world are currently experiencing extreme weather conditions- severe drought and warmer than usual temperature with acute water shortage; or unusual heavy rainfall with severe flooding. An estimated 60 million people are affected by these conditions.

These extreme weather conditions have been attributed to the El Nino effect.

El Nino:

The El Nino effect describes warming of the sea surface temperature that occurs every few years, typically concentrated in the central-east equatorial Pacific.

Due to the increase in sea surface temperature, there is a resultant alteration in wind and rainfall patterns across the equatorial pacific. These changes cause extreme weather conditions on either side (Eastern Pacific and Western Pacific) of the phenomenon.

A good explanation of the El Nino effect is provided in a video here:


Health Consequences of El Nino:


  • Both droughts and flooding may trigger food insecurity, increase malnutrition and thus enhance vulnerability to infectious diseases;
  • Droughts, flooding and intense rainfall (including cyclones) may cause loss of life, significant population displacement, water and vector-borne disease outbreaks and may damage or close health facilities, thus reducing regular health service delivery and restricting access to healthcare during the emergency and well beyond the event;
  • El Niño-related warmer temperatures may result in vector-borne disease epidemics in highland areas, which are too cold for vector survival and disease transmission at other times;
  • Damaged or flooded sanitation infrastructure may lead to water-borne diseases;
  • Extremely hot and dry conditions may lead to heat waves, wildfires, increased smoke and deteriorated air quality, causing or exacerbating respiratory diseases and heat stress;
  • Populations already affected by a humanitarian situation (e.g. in internally displaced persons and refugee camps) face heightened risk of suffering health consequences of either wet or dry conditions.
  • Globally, natural disasters such as droughts, floods and storms kill more women than men, and tend to kill women at a younger age. These effects also interact with the nature of the event and social status. The gender-gap effects on life expectancy tend to be greater in more severe disasters, and in places where the socioeconomic status of women is particularly low.


Useful Links:

Link to WHO’s Fact sheet on El Nino and Health:


Link to WHO’s page on El Nino:


Link to WHO’s page on the El Nino crisis of 2016:


Link to WHO’s Update on El Nino and Health (April 2016):


Link to WHO’s El Nino and Health global Report (21 January 2016): 


WHO’s page on Health Preparedness for the El Nino event 2015-16:


Link to WHO’s document ‘Gender, Climate Change and Health’:


Link to WHO Resources on Adaptation in the context of Climate change and human health:


Link to WHO’s Posters on climate change and human health:



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