Global Disease Outbreaks Linked to El Niño

By Allan Mai ‘20

Figure 1. A 2019 analysis of the 2015-2016 El Niño showed correlation to the change in climate and subsequent global disease outbreaks.

El Niño is a complex series of weather patterns that occurs off the coast of South America. While the last El Niño occurred three years ago, the unusually warm weather and nutrient-poor water caused a series of events that continues to affect plant and animal and life, especially those that are responsible for transmitting a disease from one organism to another. For example, cases of the plague in Colorado and New Mexico and dengue fever in Brazil are on the rise and is is directly related to the rainfall caused by El Niño; as a result, scientists are currently working to develop models to better understand and prepare for the consequences of this weather pattern in the future.

Under the direction of head researcher Assaf Anyamba of the Universities Space Research Association in Maryland, a coalition of US federal departments and agencies – NASA, the USDA (United States Department of Agriculture), and the NOAA (National Oceanic and Atmospheric Administration) – joined efforts to supply the data and satellites needed to protect public health worldwide. This interagency effort monitored the exceptionally strong El Niño event in 2015-2016 and found that caused the extreme conditions – flooding, drought, and extreme temperatures – in which climate sensitive disease vectors flourish. For example, in the United States, especially in California, there has been an increase in the occurrence of West Nile Fever after a series of severe rainfalls caused increased vegetation which, in turn, caused an increase in the mosquito population (mosquitoes are known vectors of West Nile).

Data relating to epidemiology after El Niño had never been collected at such a large scale. This study, therefore, is a step towards equipping geographical regions most affected by El Niño with valuable data to better prevent the spread of disease in the years after the weather phenomenon. This work is crucial to controlling diseases like the Zika Virus, which affected an entire generation in Brazil in 2015-2016. The researchers hope that further studies will be conducted to improve upon current models.



  1. A. Anyamba, et. al., Global disease outbreaks associated with the 2015–2016 El Niño event. Scientific Reports 9, (2019). doi: 10.1038/s41598-018-38034-z.  
  2. Image retrieved from:

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