The Zika virus circulated in many regions of the Americas for months before cases were detected, according to a study from an international research team from the Broad Institute of MIT and Harvard and collaborating institutions. Lead author was Dr. Pardis Sabeti, professor of immunology and infectious diseases at Harvard T.H. Chan School of Public Health and a Broad Institute Member.
The study was published May 24 in Nature.
The analysis of 174 Zika virus genomes — the largest collection of Zika genomes to date —revealed the trajectory and evolution of the virus as it spread throughout the Americas. The genomes were sequenced from patient and mosquito samples collected in 11 affected countries and territories, allowing the researchers to reconstruct for the first time the spread of the virus across South and Central America, the Caribbean, and into the southern United States.
The findings suggested that Zika was circulating in Brazil around February 2014, a year before that nation’s first confirmed infections were reported. Similarly, the virus appears to have arrived in Colombia, Honduras, Puerto Rico, and elsewhere in the Caribbean from 4.5 to 9 months before the first confirmed local infections.