Is El Niño to Blame for the "Explosive" Zika Virus Outbreak? [View all]

[ellenrr]

What's the cause of the outbreak? According to Laurie Garrett, senior fellow for global health at the Council on Foreign Relations, the outbreak was triggered by "a perfect storm" of biological, economic, and climatic events. Aedes aegypti, the mosquito that can carry Zika, has been growing in population in Latin America since first being introduced to Brazil via trans-Pacific shipping routes in the late 1980s. Brazil is also now in the middle of a severe economic downturn, while the government is in disarray as President Dilma Rousseff faces calls for impeachment for her involvement in a corruption scandal involving Petrobras, the state oil company. That has left the country with a weakened public health system that is struggling to effectively eradicate dangerous mosquitoes. This week, Brazil's health minister admitted he was "badly losing the battle" against mosquito-borne illnesses.

But the most important factor, Garrett said, is a mosquito population boom triggered by above-average rainfall, a product of this year's exceptionally strong El Niño in the Pacific. Over the last month, flooding in Brazil, Paraguay, and elsewhere has been the worst in half a century, forcing 150,000 people to evacuate their homes. Those conditions are perfect for mosquito breeding.

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But while it's certainly true that global warming could lead to increases in the spread of disease-carrying mosquitoes, in the case of Zika, the mosquitoes in question have been well established in the affected region for nearly two decades.

More important than changes in mosquito distribution is the change in rainfall caused by El Niño. While this El Niño wasn't caused by climate change per se, it is happening in a context of overall higher ocean and atmospheric temperatures—2015 was the world's hottest year on record—that may have helped make it stronger than usual. And there is a growing body of research finding that climate change could dramatically increase the frequency of severe El Niños, meaning that regardless of how mosquito ranges spread, places that already have mosquito problems now could see them get worse.

http://www.motherjones.com/environment/2016/01/climate-change-el-nino-zika-virus