Brazilian officials have just declared the end of the Zika pandemic, but we aren’t rid of that problem yet.

There’s a year-round community of mosquitoes around Miami which can help propagate Zika in and through the US. Image credits: Smallbones.

Researchers are preparing themselves for a potential new wave of Zika outbreaks so that this time, the diseases doesn’t catch us by surprise. A new study conducted by researchers from The Scripps Research Institute (TSRI) showed how the virus entered the United States several times and might do the same once more.

They basically sequenced the virus’ genome at several points during the pandemic, to create a family tree and understand how it spread. This is a state-of-the-art technique, which only recently became possible.

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“Without these genomes, we wouldn’t be able to reconstruct the history of how the virus moved around,” said TSRI infectious disease researcher and senior author of the study, Kristian G. Andersen, who also serves as director of infectious disease genomics at the Scripps Translational Science Institute (STSI). “Rapid viral genome sequencing during ongoing outbreaks is a new development that has only been made possible over the last couple of years.”

He and his colleagues learned that Zika was transmitted through Florida at least four (and up to forty) times, which is worrying but can also help researchers better prepare in the future. This likely happened due to the environment around Miami, which is suitable for Aedes aegypti mosquitoes, the main species that transmits Zika virus. In fact, Miami hosts year-round populations of this mosquito, and it is also a major international hub, bringing in more international traffic than any other city in the US. So you have two things you don’t really want together, and that’s how you could end up with Zika in the US.

But researchers also show how to fight this possibility: eliminate the mosquitoes.

“We show that if you decrease the mosquito population in an area, the number of Zika infections goes down proportionally,” said Andersen. “This means we can significantly limit the risk of Zika virus by focusing on mosquito control. This is not too surprising, but it’s important to show that there is an almost perfect correlation between the number of mosquitoes and the number of human infections.”

It’s not clear how Zika will evolve in the future, or what its consequences will be. After all, until recently, we didn’t even know how bad it can be, but one thing’s for sure: we’ve clearly underestimated this disease. Scientists aren’t idling, and they’re understanding Zika more and more. Hopefully, policymakers will heed their call and start preparations before a new pandemic gets underway.

Journal Reference: Nathan D. Grubaugh et al — Genomic epidemiology reveals multiple introductions of Zika virus into the United States. Naturedoi:10.1038/nature22400