Outbreak arrived in Brazil and invaded Florida several times without detection
The Zika virus probably arrived in the Western Hemisphere from somewhere in the Pacific more than a year before it was detected, a new genetic analysis of the epidemic shows. Researchers also found that as Zika fanned outward from Brazil, it entered neighboring countries and South Florida multiple times without being noticed.
Although Zika quietly took root in northeastern Brazil in late 2013 or early 2014, many months passed before Brazilian health authorities received reports of unexplained fever and skin rashes. Zika was finally confirmed as the culprit in May 2015.
The World Health Organization did not declare the epidemic a public health emergency until February 2016, after babies of Zika-infected mothers began to be born with severe neurological problems. Zika, which is carried by mosquitoes, infected an estimated 1 million people in Brazil alone in 2015, and is now thought to be transmitted in 84 countries, territories and regions.