Future increase in extreme El Nino events under greenhouse warming increases Zika virus incidence in South America

The Zika virus (ZIKV) was first found in Zika forest, Uganda in 1947. The disease appeared in the Americas, Northeast Brazil in May 2015. ZIKV propagated rapidly across the Americas and the World Health Organization (WHO) in February 2016 declared this as a public health emergency of international concern. The temperature conditions related to extreme El Niño of 2015–16 were exceptionally favorable for ZIKV spreading in South America. For the recent spreading of ZIKV, in Americas, Northeast Brazil was the starting point and it was associated with the extreme El Niño 2015–16. Paz and Semenza found that there is a striking overlap when the regions with extreme climatic conditions in 1 month are juxtaposed with the geographic distribution of ZIKV in subsequent months. They found that the unique climatic conditions generated by extreme El Niño of 2015–16 are congenial for the dispersal of ZIKV in the Americas. This is not a just coincidence and many authors noted that ZIKV vector Aedes aegypti is strongly dependent on surface climate conditions that occur during extreme El Niño events. Recently a study found that extreme El Niño events will double in future in response to greenhouse warming. Also it was discovered that the increase of extreme El Niño frequency will continue long after 1.5 °C warming stabilization. We analyze future extreme El Niño events along with associated surface temperatures and calculated the ZIKV quantitatively in future extreme El Niño events and found that large parts of South America are highly favorable for the spread of the disease.