Mosquito season is just getting underway. And many parts of the country have mosquitoes that could potentially transmit Zika.
Health officials expect to see cases here in the next few weeks. So we decided to figure out who needs to break out the bug spray and what other precautions they should take.
By now, you've probably heard that pregnant women — and those trying to get pregnant — face the biggest danger when it comes to Zika. The virus can cause devastating brain damage in fetuses at any point during a pregnancy.
That's far different from how the disease affects people who are not pregnant. For them, symptoms are usually mild. There can be a rash, joint pain and a fever. Many people won't even know they're infected, according to the Centers for Disease Control and Prevention.
But does that mean an expectant mother in New York City or San Francisco needs to be just as concerned as one in Houston?
In general, you can break the continental U.S. into three zones, based on the risk of having local transmission of Zika this summer:
- Extremely low-risk zone: This is the northern half of the country, from northern New England across the north Midwest to the Pacific Northwest. These states don't have the main mosquito — Aedes aegypti — that can spread the virus. Pregnant women can relax in this zone.
- High-risk zone: "What we're talking about, the really risky areas are Florida and the Gulf states into Texas," Scott says. These regions have high densities of A. aegypti mosquitoes. And they've had outbreaks of two viruses related to Zika: dengue and chikungunya.
"Zika will go where dengue has been, to some extent," says Dr. Karin Nielsen, a pediatric infectious disease expert at the University of California, Los Angeles.
"I think pregnant women should stay away from areas that have had dengue outbreaks in the continental U.S.," which includes the Florida Keys, Houston and the border of Texas and Mexico, she says.
- Low-risk zone: This is the rest of the country, including the Southeast, the Mid-Atlantic states — all the way up to New York City and Long Island — and the Southwest.
Scientists may have found A. aegypti mosquitoes in parts of these states. But there are far fewer of these mosquitoes here. So the risk this summer is very low in places like Washington, D.C., Atlanta and San Francisco, Scott says.
Still, though, it's possible.
So if his wife was pregnant and living in one of these low-risk zones, he would have her start taking precautions now, just to be safe.
"You just never know," Scott says. "The outcome of [getting infected] is really tragic. And so, you know, I think you want to make sure that you avoid that."
To do that, pregnant women need to start avoiding mosquito bites, says Scott Weaver, who studies Zika at the University of Texas Medical Branch in Galveston.
They should start wearing long-lasting insect repellent, long sleeves and long pants, even during the daytime. "These are daytime biting mosquitoes, and they're mosquitoes that like to enter peoples' home," he says.
These precautions also apply to two other groups: pregnant women's partners, because Zika can be transmitted sexually; and people with suppressed immune systems, because they could have more severe complications from a Zika infection.
Another good strategy is to figure out if your community has A. aegypti mosquitoes, Weaver says. "Check with your local mosquito-control district and see if they've detected A. aegypti near your home," Scott says.
If they have, clean up your yard. Keep it free of containers that hold standing water, where mosquitoes can breed. "It can be something as small as a bottle cap and have enough water for mosquito larvae to develop," Weaver says.
Finally, know the enemy. A. aegypti mosquitoes have white stripes on their legs and a marking in the shape of a lyre on their backs. Learn to recognize them. And stay away.