Maybe you first came across the word in a random newspaper headline. On first glance, it probably didn’t register with you at all. Something about a disease in Brazil, or something. Next article.

But then it pops up again, on your Facebook newsfeed, a week later. Then, maybe you see something about it on the TV. Perhaps, you tune in this time: Twenty-one countries affected across the Americas. Images of crying babies with shrunken heads. Pregnant women warned not to travel to affected areas. Then you hear about cases reported in the U.S.—Texas, Florida, and now Alabama. Slowly, you start to wonder: Is this a thing? Should I be concerned?

If the word “Zika” meant nothing to you until very recently, you’re not alone. Even the scientific community is trying to play catch-up.

The Zika virus is a tropical disease spread primarily through mosquitos, similar to West Nile, dengue or yellow fever. And until recently, that was basically all scientists knew about it. First discovered in Uganda in 1947, it was isolated to parts of Africa and Asia for decades. Known cases were few, and often too mild to warrant much attention. In fact, no major outbreaks had ever been recorded until 2007, when it reached an island in Micronesia. Periodic outbreaks soon followed on other Pacific islands, causing some scientists to start asking questions. But, it still flew well under the radar of most public health officials.

That all changed when Zika reached South America last year. Since last May, when the first confirmed case was reported in Brazil, the disease has spread like wildfire across the continent and has now reached epidemic levels, affecting 21 countries in the Americas and the Caribbean.

Part of the reason why it was ignored for all of those years is that 80 percent of those affected show no symptoms at all; the remainder may experience a rash, headaches, joint pain or a mild fever, but rarely is it life-threatening. It usually passes within a week.

However, now scientists are primarily concerned about the risk of pregnant women passing the disease to their unborn children. The virus has been linked to microcephaly, a condition that causes infants to be born with abnormally small heads and experience severe developmental issues. Though the defect can be caused by a wide variety of factors, a dramatic spike in microcephaly has coincided with the arrival of Zika in affected areas, suggesting a correlation. In Brazil alone, the number of cases has risen to over 4,000 in the months since the outbreak began, far more than the 150 cases the country usually sees annually. Likewise, there is also evidence to suggest that Zika may be related to Guillain-Barre syndrome, a crippling neurological disease.

Due to the evolving nature, viruses are notoriously difficult to identify, monitor and contain, let alone eradicate. Add to that the relative lack of knowledge surrounding the Zika virus, and it may appear that we have a recipe for disaster. But, to its credit, the World Heath Organization (perhaps drawing on their recent experiences with the Ebola outbreak) has quickly responded to the threat and is working around-the-clock to study the nature of this infection to combat its spread. It is now believed that the disease can be spread through sexual transmission; in addition, “live” samples of the virus have been discovered in urine and saliva.

Still, experts say a vaccine could take two years to develop and as long as a decade to implement. The Center for Disease Control has warned women who are pregnant or may become pregnant to avoid countries where the outbreak is occurring. Governments in affected areas have even urged women to avoid getting pregnant until the crisis passes, in some cases for as long as two years.

As such, the Zika virus is leaving its mark on Latin American society in unexpected and possibly long-term ways. The fear of Zika has cast an unwelcome shadow over the upcoming 2016 Olympic Games in Rio de Janeiro. In addition, the focus on delaying pregnancy and the risk of birth defects has sparked renewed debates about birth control and abortion in many countries, in a region where the Catholic Church remains a potent political force (Currently, Cuba and Uruguay are the only two Latin American countries where abortion is cheap, safe and widely available).

Is America at risk? The answer is probably no. Though the U.S. is home to the type of mosquito responsible for Zika’s spread, so far, there have been no reported cases of local transmission. Of the at least 35 cases reported in the U.S., all have been “travel-related”—involving people returning from affected areas.

However, as a nation, we should not be lulled into a false sense of security. While it is true that we have many institutional advantages at our disposal to prevent an outbreak, no one is immune.

We like to think of pandemics as third-world anomalies, some long-forgotten relic from a simpler era. But as many medical advances we make, viruses are adapting just as quickly. And in our increasingly interconnected world, they can travel faster and farther than ever before.