Tracking Zika: Virus hit earlier than expected in Brazil, Florida

CHICAGO – Studies using gene sequencing equipment to trace the path of Zika by the America’s show the virus came a year before the first case was discovered in Brazil, and a few months before it was first reported in Florida.

The findings, published in three various articles in the journal Nature, come from nearly 200 Zika virus genome sequences collected from the infected persons and mosquitoes that transmit the virus.

Collectively, they demonstrate the potential for newer, more portable gene sequencing equipment for fast detection of the spread of new infectious diseases, experts said.

In one study, a team led by Oliver Pybus of the University of Oxford found that Zika first arrived in Brazil in the beginning of 2014, for the full year prior to the first confirmed cases in May 2015.


Pybus’ research focused on how the virus an early foothold in the northeast of Brazil, from which it spread to other areas. The northeast of Brazil is the region with the most registered cases of Zika and microcephaly, a birth defect caused by the virus is characterized by small head and brain size.

Pybus said the region was “the nexus of the epidemic in Brazil and played an important role in the spread of the virus to other big Brazilian cities such as Rio de Janeiro and Sao Paulo, in south America.

His team was part of a consortium of British and Brazilian scientists that traveled throughout Brazil in a minibus, the analysis of samples of the virus with the help of Oxford Nanopore Technologies, pocket-sized MinION DNA sequencer. The portable device was used in 2015 to follow genetic changes in the Ebola virus, as it developed and spread in Guinea.

A joint study led by Pardis Sabetti and colleagues from the Broad Institute and Harvard University used data from 174 genomes sequenced from patients and mosquitoes samples collected in 11 different countries or territories.

The data allowed the team to follow the spread of the virus in South and Central America, the Caribbean and in the south of the United States.

They found that Zika had been circulating in Colombia, Honduras, Puerto Rico and other parts of the Caribbean from 4.5 to 9 months before the first local infections were confirmed.


In another paper, Kristian Andersen, of the Scripps Research Institute in La Jolla, California, and colleagues, specifically aimed at Zika, the introduction in Florida.

Andersen’s team sequenced 39 Zika virus genome from infected patients and mosquitoes in and around Miami, Florida. They discovered that Zika was introduced into the local mosquito populations in Florida at least four times, probably from infected travellers from the Caribbean.

He believes that the virus began to circulate in Florida in the spring of 2016, months before the first reported case in July.

Andersen said these infections picked up in Florida mosquito population, because Florida is one of the rare places in the United States, where Aedes aegypti mosquitoes – that transmit Zika, are present throughout the year. The other place in the continental United States is Brownsville, Texas, which also had local sent Zika cases in 2016.

“In all likelihood, that means that the majority of the United States is probably not at risk of Zika outbreaks,” Andersen said in a conference call. It also means that the mosquito control efforts, can go a long way in the direction of preventing outbreaks, ” he said.

Bronwyn MacInnis of the Broad Institute said that the studies show the power of the use of gene sequencing to trace emerging infections, and could have helped detect the virus much earlier.

“We were way behind the curve on Zika. We must also move forward to the next emerging viral threat, and genomics can play a role in achieving this,” she said.

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