Here are the places Zika would most likely be transmitted if it became an issue in the US
It's expected to arrive in every country in the Americas with the exception of continental Chile and Canada, but it remains to be seen which parts of the US - if any - become hot spots for local transmission.
There is no vaccine or treatment for the virus, though the National Institute of Allergy and Infectious Diseases expects early trials of a potential Zika vaccine to start by the end of this year. Zika is transmitted mainly via mosquitoes, though there has also been a recent incident in which the disease was transmitted sexually from one infected person to another healthy person.
Once infected, only about one in five people with Zika ever shows symptoms, which most commonly include fever, rash, joint pain, and red eyes. The disease has been linked to a brain condition called microcephaly, which has raised concerns about pregnant women contracting the virus.
Zika is carried by mosquitoes, namely the Aedes aegypti, a tropical bug that's great at transmitting diseases like yellow fever, dengue, and Zika. They are daytime mosquitoes, which means they bite during the day and like hanging out in warm, damp, heavily-populated locations.
So what does that mean for the US? Here's a map of where the Aedes aegypti and another virus-carrying mosquito, Aedes albopictus, live:
The US and Zika
Before you panic and move to Canada, it's important to know there is not a lot of cause for concern in the US, at least not the way things are looking now. But in the spring and summer, things may be a little different.
"I would not be surprised to see some sporadic small outbreaks in the United States maybe in the warmer months in certain areas like the Gulf Coast or California or Hawaii," Alex Perkins, a Notre Dame biological sciences professor, told Business Insider.
But even then, Perkins added: "I don't think it's really going to be a major concern in the US."
Here's why: Researchers think what happens with Zika will be similar to what's happened with other mosquito-borne diseases in the US like dengue and chikungunya, both which have been locally, periodically transmitted in southern parts of the country, but haven't ever turned into a nationwide problem. For example, Dengue infects an estimated 50 to 100 million people globally per year, with some 22,000 deaths related according to the CDC. In comparison, the US rarely has local transmission, and very few deaths related to outbreaks. Chikungunya has only had local transmission in Florida and US terrirories.
Some researchers say Zika is not even worth worrying about unless you fit into a specific group.
"The average American is very unlikely to be touched in a meaningful way by Zika unless they are pregnant and are going to be traveling in areas where it's being transmitted," Dr. Andrew Pavia, Chief of the Division of Pediatric Infectious Diseases at the University of Utah Health Care, told Business Insider.
So far, there has been no local transmission of the virus via mosquito in the US - it has been diagnosed only in people who have recently traveled to Zika hot spots, areas where local transmission is actively happening. The CDC anticipates that local transmission will happen in the US at some point, but the agency has said they expect it will be similar to outbreaks of dengue and chikungunya, which have been relatively contained to southeastern American states.
What the US has going for it
What makes the Aedes aegypti mosquito tricky to get rid of is that it's a daytime mosquito that's good at hiding in warm, damp places - often these are inside homes rather than outside. That means efforts to spray areas with pesticides can miss the mosquitoes hiding out indoors.
To fend off indoor mosquitoes, Principal Deputy Director of the CDC Dr. Anne Schuchat told reporters on a conference call last week that air conditioning and window screens should come in handy. Another positive thing the US has going for it includes the fact that its urban areas are less densely populated than comparable areas where the virus has affected Central and South America.
Still, this outbreak could serve as a wake-up call for the globe, Pavia said.
"It's a good time to sit back and ask some questions about are we really ready to handle emerging infections? Do we take them seriously enough before we actually face an outbreak? The answer to that is pretty obvious: We react often after a new disease has broken out and is threatening us."
Because it's nearly impossible to predict what the next big outbreak might be (Zika wasn't a big deal before its first major outbreak in 2007), creating a system that can respond quickly to emerging infections is key, Pavia said. Whether that be through mosquito control, better surveillance, or retaining funding for public health agencies, the next outbreak could be addressed a lot more proactively than Zika has been.