A mosquito-borne virus that may have caused serious birth defects for thousands of babies in Brazil made its way to Puerto Rico by the end of last year, and experts are grappling with what this means -- if anything -- for North America.
Zika has been characterized in the past as an annoying but generally harmless sickness, with symptoms like rash, fever, joint-pain and red eyes. In fact, about one in four who get infected with disease probably don't even notice they have it.
But when the virus became widespread in Brazil in 2015, with an estimated 500,000 to 1.5 million residents contracting Zika, health officials noticed that it coincided with a sharp increase in microcephaly, a condition in which a fetus' brain doesn't grow to full size and the baby is born with an abnormally small head.
Between 2010 and 2014, Brazil had an average of 156 babies born with microcephaly each year. But in 2015, over 3,000 babies were born with the condition, reports The Wall Street Journal. So far, authorities are investigating these babies, as well as deaths that are suspected to be linked to microcephaly, to see if they harbor any trace of the Zika virus.
If Zika follows the same migratory patterns as other mosquito-borne viruses like dengue fever and the chikungunya virus, experts say Texas, Florida and Hawaii could be at risk of an outbreak in the future.
With that in mind, here are four things you should know about Zika and its potential spread to the U.S.
1. The link between Zika virus and microcephaly is suspected, but not confirmed.
The lifelong consequences of microcephaly could include mental retardation, developmental delays, dwarfism and seizures, although some children with the condition grow up to have normal intelligence and development.
While the potential link between a mosquito bite and lifelong birth defects is scary, it’s important to note that a lot of different things can cause microcephaly, like certain genetic disorders, exposure to toxic chemicals and even a traumatic birth. Brazilian health officials say there is a link between Zika and microcephaly, but experts from the World Health Organization and others who spoke to The Huffington Post are still reserving judgment.
Dr. Anna Durbin, a vaccinologist and expert in dengue fever from Johns Hopkins Bloomberg School of Public Health, praised Brazil for their vigorous investigation into the matter but echoed WHO’s perspective -- it’s too early to say that the virus causes this or any birth defect.
"The appropriate approach is to say we’ve had a large increase in microcephaly, we don’t know the cause and we’re concerned about the fact that we’re also having a Zika outbreak,” said Durbin. "But to say there’s a link when it hasn’t been confirmed is actually more problematic.”
After a large outbreak of Zika virus in French Polynesia in 2013, experts suspected a link between the disease and neurological complications like Guillain-Barré syndrome, which has symptoms including tingling in the legs and arms and paralysis. However, Zika had never before been linked to pre-natal or birth complications until Brazil started noticing the uptick of microcephaly.
Currently, some Brazilian doctors are advising women to avoid getting pregnant while officials figure out what’s going on, and women in Brazil who are currently pregnant say they’re feeling extremely stressed about the news.
2. Zika virus is spread by mosquitoes.
Zika was first discovered in 1947, and has broken out in different countries in Africa, Southeast Asia and the Pacific Islands. Over the past year, the disease has also spread in parts of Central and South America.
The mosquito Aedes aegypti is the most common carrier of the disease, and Aedes albopictus is another potential vector. They originate from Africa and Asia, respectively. Aedes albopictus, also known as the Asian tiger mosquito for its white stripes, is considered the most invasive species of mosquito.
Both species typically bite during the day and at dusk, which is why mosquito nets for sleeping aren’t useful in the fight against Zika, according to Durbin. Each species can also infect people with dengue, chikungunya and yellow fever, causing serious problems in other parts of the world. America’s widespread use of air conditioning and window screens has prevented these illnesses from becoming major epidemics in the U.S.
3. Dengue and chikungunya are already in the U.S., and experts think Zika may follow.
The reason experts suspect Zika might become endemic -- defined as transmission that occurs in the U.S. -- is because the same mosquitos that carry the virus have also caused recent dengue and chikungunya outbreaks in Texas, Florida and Hawaii.
While this doesn't sound like good news, these outbreaks are also examples of what the U.S. gets right when it comes to mosquito-borne diseases: air conditioners and window screens are the norm, and local governments vigilantly monitor and eradicate disease-causing mosquitoes.
"Despite going through a similar rapid spread through Latin America about 15 years ago, [dengue] hasn't really ever done more than appear sporadically in the U.S.A.," said Derek Gatherer, a researcher who specializes in the evolution of viruses at Lancaster University in the U.K.
On the other hand, West Nile virus, another disease that spreads through mosquitoes, has been able to permanently establish itself in the U.S. because it can survive in humans, horses, and birds, giving the virus a wider variety of hosts. Zika, dengue and chikungunya generally only survive in humans.
"Zika might well be more like dengue and chikungunya and less like West Nile virus -- we'll just have to wait and see,” said Gatherer. "If it is like dengue, then Zika might just stop at the Mexican border" because of mosquito control efforts in the U.S.
4. Prevention is paramount.
There is no vaccine for Zika virus, and no cure other than rest, plenty of fluids and perhaps over-the-counter medication to reduce fevers, aches and pains. Because of this, prevention is paramount.
If you’re flying to a country where Zika virus is endemic, take anti-mosquito measures seriously. Put mosquito repellant on your clothes and skin, wear long sleeves and pants, and sleep underneath mosquito nets at night -- even though the mosquitos that transmit Zika are mostly daytime biters, you'll rest easier. In December, the Centers for Disease Control and Prevention issued a travel warning with all of this advice to Americans going to Mexico, the Caribbean and other parts of Central and South America.
If after your return you start to feel any sickness that requires care, be sure to tell doctors and nurses immediately about your most recent trip. Zika’s symptoms are similar to many other diseases and can be easily confused with the common cold or another mosquito-borne disease.
The CDC warns that if you actually do come down with Zika virus, it becomes even more important for you to avoid mosquitoes -- you don’t want to be able to give the insects something they can spread to other people.
More broadly, the most effective way to guard against zika virus is to guard against mosquitos in general. That means ferreting out puddles of standing water on your property, setting traps for mosquitoes and perhaps calling your city or county’s vector control services to fog areas with chemicals that can kill the insects or their eggs.
"The concern really should be about mosquito control and prevention of mosquito bites, rather than concern or fear about a specific disease,” said Dr. Andi Shane, a pediatric infectious diseases expert at Emory University. “If we can control the vector, it's less likely that we’ll have the infection."
CORRECTION: A previous version of this story stated that both the Aedes aegypti and Aedes albopictus were known vectors of the Zika virus. However, Aedes albopictus is only a potential vector at this time.
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