Zika Virus in Brazil Since 2013 Study Says

According to an analysis of several Zika virus genomes published Thursday in Science, the first Zika virus case in Brazil could have been diagnosed as early as 2013, nearly two years ahead of first reported case.

The first diagnosis of Zika outbreak was made in May 2015, but the virus could have affected people much earlier. Brazil registered health problems marked by fever and rashes in mid-2014, but health officials could not identify the new virus's presence as no commercial tests were available for the diagnosis of the virus's attack.

The study reveals that Zika could have been carried into French Polynesia which recorded an outbreak from 2013 to 2014. If the outbreak of the virus were diagnosed in Brazil in 2013, the effect of the virus on human beings could have been minimized.

The virus is linked with microcephaly, a birth defect which results in small heads and brain damage in infants. The virus also causes infant eye abnormalities and Guillain-Barre Syndrome that causes temporary paralysis. There is no treatment for microcephaly and no vaccines to stop Zika outbreak.

The Zika virus spread to various regions due to international travel to Brazil. The country hosted many important sports events in 2013-14, including FIFA Confederations Cup, the men's soccer World Cup and a canoe competition. Large number of people visited Brazil during these tournaments, the study notes.

"It's easy to see how Zika could have flown under the radar for a year or more," said Scott Weaver, director of the Institute for Human Infections and Immunity and scientific director of the Galveston National Laboratory in Texas.

The diagnosis of Zika virus is critical because 80% of people affected by the virus show no special symptoms. When they do show symptoms, they are negligible. The symptoms include fever, mild rashes, joint pain and pink eyes.

According to the World Health Organization, Zika is now spreading "explosively," causing outbreaks in more than 30 countries and territories in the Western Hemisphere.