The Link Between El Niño and Disease
New research shows, for the first time, the strong connection between El Niño weather patterns and increased outbreaks of infectious disease around the world. Published by Scientific Reports, the analysis is the result of collaborations between our scientists and those from NASA, the Department of Defense, and the USDA.
Analyzing data from the abnormally strong 2015-2016 El Niño, scientists found increases in incidences of diseases like chikungunya, hantavirus, Rift Valley fever, cholera, plague, Zika, and more. As prior research has found the connection between global climate change and increasingly intensified El Niño activity, this study marks one of the first times globally linked weather patterns and infectious disease rates have been definitively linked.
“We’ve understood the connection between climate and public health for some time; we call it One Health,” EcoHealth Alliance Executive Vice President for Health and Policy and co-author Dr. William Karesh said. “But one of the novel discoveries in this research is its predictive potential: in identifying the warning signs before outbreaks, we can lessen their intensity or prevent them altogether.”
The paper’s authors recommend “routine and ongoing global satellite monitoring” of climate anomalies linked to El Niño. These are regionally specific and include: increased rainfall, sea surface temperature, and land surface temperature.

El Niño is the warm phase of El Niño-Southern Oscillation (ENSO) marked by warmer surface sea temperatures, high air pressure in the western Pacific Ocean, and low air pressure in the eastern Pacific. Its effects vary by region but areas with more rainfall see higher rates of disease spread by mosquitoes and other vectors which take advantage of the favorable mating conditions, for example.
The importance of knowing environmental conditions which lead to infectious disease outbreaks is its ability to prevent. The Scientific Reports study provides a set of weather anomalies for which to look. When these are observed, preparations can be made and interventions enacted so as to limit the scope and harm caused by the disease outbreaks which follow El Niño.

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