New study shows Zika arrived in Brazil in 2013

The Zika virus arrived in Brazil in 2013, far earlier than previously thought, according to a study released Friday by scientists.

This conclusion was reached after isolating and separately studying seven different samples of the virus from across Brazil, by analyzing trips taken by passengers from zones where Zika is endemic or from Pacific islands which have suffered Zika epidemics, said scientists of the University of Oxford and the Evandro Chagas Institute, a non-profit organization which promotes public health in Brazil.

The seven different analyses showed a very small difference in variables, with all results pointing to a single point of entry of Zika into Brazil between May and December 2013.

Flight registries show, according to the scientists, that passengers arriving in Brazil from zones where Zika was present increased in that period. From the end of 2012 to the period in question, there was a 50 percent jump in the number of such arrivals, increasing the risk of bringing the virus to the country.

One hypothesis is that Zika entered Brazil during the Confederations Cup, which took place in June 2013 as a test event before the 2014 World Cup. The Tahiti team, hailing from French Polynesia which was suffering a Zika epidemic at the time, took part in this tournament.

Brazil has been the worst-hit by Zika, which has spread progressively around the country, leading the government to declare a national public health emergency. While conclusive medical evidence is still lacking, it is believed the virus has caused thousands of cases of microcephaly among babies, especially in the northeast. Endi