Zika is full of surprises. The mosquito-borne virus has captured international attention since the outbreak in Brazil early in 2015, and is now active in 60 countries around the world. In the seven decades that we've known about Zika, it has always appeared to be relatively harmless, no more alarming than a minor flu. But in the last year we've discovered that it can cause severe birth defects, miscarriages, and neurological disorders, and with research on this outbreak just beginning, we still don't know what other long-term developmental problems the virus could cause. And now, as the wet, hot summer months begin, conditions are getting even more mosquito-friendly – meaning Zika could potentially spread. We spoke with the Center for Disease Control's Dr. Tyler Sharp, an epidemiologist who is heading up the Zika research team in Puerto Rico, to tell us what we need to know about the mysterious disease.
Zika symptoms are mild enough that you may not know you have it.
On the surface, Zika doesn't feel like a big deal. The symptoms are relatively mild: fever, achy joints, a rash, and conjunctivitis (red eyes). And that's if you have any symptoms at all – 80 percent of the time people don't. Before this outbreak, research on Zika was sparse, because it seemed pretty harmless. "It was a very boring virus," says Dr. Sharp. "It causes a rash, maybe some red eyes for a couple days and then it goes away. Big whoop."
But it changed its tune last year.
This outbreak uncovered a much more dangerous side of the virus – likely because it was widespread enough to reveal some of its less common side effects. Zika is the only mosquito-borne virus to be shown to cause birth defects – most alarmingly, microcephaly, which causes babies to be born with undersized brains and heads. It's also connected to Guillain Barré Syndrome in adults, a condition where the immune system attacks your nerves, causing weakness and temporary paralysis. And with research still in its infancy, we don't know how often these side effects can occur.
The virus only stays in your blood for about a week.
Which is about as long as the West Nile or dengue fever. And so far it looks like there's no immediate risk to pregnant women after it leaves her bloodstream. But it can stick around in other bodily fluids for much longer, like saliva, urine, and semen.
We get it from mosquitoes, mostly.
The majority of Zika cases come from mosquito bites. It's carried by the female Aedes aegypti mosquito (and less frequently, by its cousin the Aedes albopictus), the same one that carries dengue and yellow fever. If a mosquito bites a person that's carrying the Zika virus, it can pass it on to anyone it bites later – as many as 15 of them in their one-month life span. These mosquitoes evolved alongside humans, and our blood is their "preferred" meal. They live as close to us as they can, and breed in the standing water that accumulates in flower pots, pools, discarded trash – it doesn't need to be bigger than a bottle cap.
But also, it's transmitted by sex.
Researchers recently confirmed that Zika can be sexually transmitted – at least through semen. Studies have found Zika in semen as long as 62 days after symptoms start, which means a man can transmit the virus to a partner long after he's visibly recovered. "We don't have evidence that it can pass through vaginal secretions yet," but with new discoveries at every turn, Sharp says it could just be a matter of time. In France, one case even suggested that you can pass the virus through oral sex. This was a surprise to researchers studying Zika because, just like they've never seen a mosquito-borne virus cause birth defects, they've never seen one that can be sexually transmitted.
There's a good chance that we'll see small, local outbreaks in the states.
So far, the states have confirmed 756 Zika cases, but just about all of them have been travelers who were bitten – or had sex – in a country currently dealing with an outbreak. (One person contracted the virus while studying it in a lab.) We haven't had a local outbreak of our own, meaning that an infected mosquito hasn't bitten someone within the 50 states. That said, with 40,000 travelers passing in and out of Zika-infected areas, it's likely only a matter of time. Because it's carried by the same mosquito that carries Dengue and Chikungunya, health officials are using the patterns of those viruses to anticipate where Zika is most likely to show up. "If history is any measure," says Sharp, "it's gonna be south Florida, south Texas or Hawaii. Or maybe all three." And with summer in full swing, our chances are getting higher. "The warmer it gets, and the wetter it gets, the more mosquitoes are gonna be around," says Sharp.
Mosquito-borne viruses like Zika hit lower-income communities the hardest.
If you don't have air conditioning or screens on your windows and doors, you're more likely to get bitten by mosquitoes. "Lower socio-economic status is associated with getting bitten by mosquitoes more," says Sharp, "regardless of the number of mosquitoes out there." And so lower income areas of south Texas, south Florida and Hawaii are even more at risk.
Still, chances are, you're not going to get Zika at your next barbecue.
The vast majority of Americans are never going to be exposed to the Zika virus. "People worry, 'Am I gonna get it in my backyard at my 4th of July barbecue?'" says Sharp. "But no, you're fine." The Aedes mosquito lives in the Southern U.S. and up through California and New York along the coasts, but we don't have the conditions for a widespread outbreak. First, half of the country has freezing winters that are very effective in thinning out the mosquito populations. And then in the summers, we overwhelmingly live and work in hermetically sealed, air conditioned buildings. "That doesn't mean that we won't see a case in, say, New Jersey," says Sharp. "Especially in the summer months." But with less exposure, the risk of getting Zika from an infected mosquito is extremely low.
Pregnant women should avoid any areas with Zika outbreaks.
Pregnant women are by far the most at risk group in this outbreak. The World Health Organization has recommended that doctors in Zika-affected areas encourage their patients to put off getting pregnant, and the CDC is focusing their efforts on treating and monitoring pregnant women and infants affected by Zika in those areas. In terms of travel to areas with Zika, if you're pregnant or trying to conceive, just don't do it. If you're a man and your partner is either pregnant or trying, consider either delaying your trip or delaying your baby plans. But if you do have to travel, the CDC recommends that you either abstain or use a condom for two months after you get back. (Eight months if you show symptoms of Zika.) And yes, that includes oral sex.
Otherwise, if you want to safely travel, just be prepared.
If you are planning to travel to an area with Zika, the CDC and the WHO recommend a few simple precautions. Avoiding Zika means avoiding mosquito bites, so if you're in an area with Zika, use strong, long lasting bug spray, wear long sleeves and pants, and stay somewhere that's air conditioned or has window screens. Prevention is fairly straightforward, Sharp says. "It's like putting on a seatbelt when you get in the car."