Disease outbreaks triggered by El Niño

El Niño weather sign

A new study by NASA has found that the 2015-19 El Niño event brought weather conditions that triggered regional disease outbreaks across the globe. This is the first study to comprehensively assess the public health impacts of El Niño on a global scale.

The researchers found that changes in precipitation, land surface temperatures and vegetation created and facilitated conditions for disease transmission, resulting in an uptick in reported cases of plague and hantavirus in Colorado and New Mexico, cholera in Tanzania and dengue fever in Brazil and Southeast Asia, among others.

“The strength of this El Niño was among the top three of the last 50 years, and so the impact on weather – and therefore diseases in these regions – was especially pronounced,” said lead author Assaf Anyamba, a research scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. “By analysing satellite data and modelling to track those climate anomalies, along with public health records, we were able to quantify that relationship.” Anyamba said that the strong relationship between El Niño events and disease outbreaks underscores the importance of existing seasonal forecasts.

He explained that regular seasonal forecasts can save lives: “A lot of diseases, particularly mosquito-borne epidemics, have a lag time of two to three months following these weather changes," he said. "So seasonal forecasting is actually very good, and the fact that they are updated every month means we can track conditions in different locations and prepare accordingly. It has the power to save lives.”