Who Should Be Worried About Zika And What Should They Do?

May 17, 2016
Originally published on July 30, 2016 12:29 pm

It's official. Zika has come to Florida.

Four people caught the virus in a small neighborhood north of downtown Miami, Governor Rick Scott said Friday. That means mosquitoes in the neighborhood became infected with Zika and spread it.

Health officials are working hard to stop the outbreak. And they don't expect the virus to spread extensively.

But in the meantime, what precautions should the rest of the country take?

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.

Right now, the Centers for Disease Control and Prevention isn't advising pregnant women to avoid travel to Florida, the agency's director, Dr. Thomas Frieden said Friday at a news briefing. The cluster of cases is too small to warrant travel restrictions, he said.

But other doctors in the county are being more cautious.

"I'll be advising pregnant women not travel to Miami-Dade and Broward Counties in Florida, at the very least" says Dr. Neil Silverman, a maternal-fetal medicine expert at the University of California, Los Angeles. He'll also be testing pregnant women for Zika after they return from these counties.

But what about women who aren't traveling this summer? Does an expectant mother in New York City or San Francisco needs to be just as concerned as one in Florida?

"Absolutely not," says Thomas Scott, an epidemiologist at the University of California, Davis, who has been studying where Zika is most likely to appear in the U.S.

Although a map from the Centers for Disease Control and Prevention divides the continental U.S. into two zones, Scott says there are actually 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.
  • 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 the mosquitoes there. 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 a low-risk or high-risk zone, 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.

And they should avoid travel to the high-risk zone in the U.S., 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. "Zika will go where dengue has been, to some extent."

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.

Copyright 2017 NPR. To see more, visit http://www.npr.org/.

RENEE MONTAGNE, HOST:

Mosquito season is upon us, including those that potentially transmit the Zika virus. Michaeleen Doucleff of NPR Science Desk has some tips on what you should be doing about that.

MICHAELEEN DOUCLEFF, BYLINE: First off, whether or not you need to worry about Zika depends on where you live. Thomas Scott is an epidemiologist at the University of California, Davis. He has been mapping out where Zika is most likely to appear in the U.S.

THOMAS SCOTT: I think we need to be really careful about how we present this kind of information and what the risk is in various parts of the United States.

DOUCLEFF: Because, Scott says, a large part of the United States doesn't need to worry about Zika. That's the northern half - most of New England, all the way across to the Pacific Northwest. These states don't have the main type of mosquito that carries the virus. At the other extreme is the high-risk zone.

SCOTT: Really, what we're talking about - the really risk areas are Florida, the Gulf states and Texas.

DOUCLEFF: That's because the Gulf states and Florida have lots of Aedes aegypti, the mosquito that spreads Zika. What about the rest of the country, like the Mid-Atlantic states or California in the Southwest? Scott says that's a little trickier. These regions do have mosquitoes that can transmit Zika, but there's far fewer of them, so the risk this summer is very low in places like Washington D.C., Atlanta and San Francisco. But still, Scott says, if his wife were pregnant and lived in low-risk Washington D.C., he'd have her start taking precautions now, just to be safe.

SCOTT: Yeah. I mean, you just - you never know. And that is such an important thing. The outcome of this is really tragic. And so, you know, I think you want to make sure that you avoid that.

DOUCLEFF: Pregnant women and those trying to get pregnant face the most danger from Zika. The virus can cause severe brain damage in fetuses.

CATHERINE SPONG: Having Zika virus at any time during pregnancy is associated with risk for the developing fetus.

DOUCLEFF: That's Dr. Catherine Spong, the acting director of the National Institute of Child Health and Human Development. She says the second group who needs to be concerned are the partners of pregnant women because Zika can be transmitted sexually.

SPONG: Right. So if a couple is interested in getting pregnant, both of them need to take precautions.

DOUCLEFF: We'll get to those precautions in a second. The third group, Spong says, is one that hasn't gotten much attention - people who have weakened immune systems from an illness or a drug. They're more likely to have severe complications from Zika. And now the precautions - if you're in one of these groups, what should you be doing?

Scott Weaver studies Zika at the University of Texas Medical Branch in Galveston. He says don't travel to countries where Zika is circulating. And when you're at home, avoid mosquitoes and wear long-lasting repellent. The Centers for Disease Control and Prevention says DEET is fine if you're pregnant. And wear long sleeves and pants, even during the daytime.

SCOTT WEAVER: These are daytime biting mosquitoes. They're mosquitoes that like to enter people's homes.

DOUCLEFF: So Weaver says clean up your yard, especially if you live along the Gulf Coast, where the risk is highest. Keep it free of containers that hold standing water where mosquitoes can breed.

WEAVER: Can be something as small as a bottle cap - can have enough water for mosquito larvae to develop.

DOUCLEFF: Finally, Weaver says, know the enemy. Mosquitoes that can carry Zika have white stripes on their legs. Learn to recognize them and stay away. Michaeleen Doucleff, NPR News. Transcript provided by NPR, Copyright NPR.