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At least 15 people have been infected with the Zika virus after being bitten by mosquitoes in south Florida. Pregnant women are advised to steer clear of the area north of Miami where the cases occurred — and women considering pregnancy who have been to the neighborhood are being told to wait 8 weeks first.
The unusual warnings comes as the Florida Department of Health is conducting urine tests of people in the one-mile square area to see how many more people may have been exposed to mosquitoes carrying the Zika virus.
The first cases of local Zika infection in the US were confirmed in Florida last week. Florida health officials are taking emergency measures to eradicate the mosquitoes in the Miami area, spraying and getting rid of standing water.
There is a risk of larger outbreaks in and beyond Miami. Fortunately, the Aedes mosquito doesn't travel more than 150 meters (450 yards) in its lifetime and typically dies within 30 days. And because people in the US live in air conditioned homes, they are also less likely to be bitten.
But health officials aren't sure yet if it's limited to the one-square mile area or is expanding.
"We're not taking this lightly, we're preparing as best as we can for the worst," Dr. Anthony Fauci, head of the National Institute for Allergy and Infectious Diseases said Friday. "But we do not believe that there will be a widespread outbreak. There will be local transmission as we're seeing right now with these four cases."
It's important for pregnant women in the area to avoid exposure, to wear DEET, cover their arms and legs and avoid mosquito bites.
Do I need to worry about Zika?
All evidence suggests that most people do not need to worry about Zika.
"About four out of five people with infection show no symptoms," Frieden said Friday.
The people who need to worry most are pregnant women or women who could become pregnant.
Zika’s been shown to cause severe birth defects in babies born to women who are infected while pregnant. And because half of all pregnancies in the U.S. are unplanned, any woman who might potentially become pregnant needs to worry — and so do her sexual partners, because Zika can be passed on by sex.
Zika can also cause Guillain-Barré syndrome and other neurological complications in rare instances, just as many other infections do. There’s not any good way to predict who’s most at risk of these complications, so the advice is for everyone to avoid getting infected, if at all possible.
How do I avoid mosquito bites?
Stay away from areas where mosquitoes are circulating. But that’s not always possible.
Repellents work well, and despite fears about chemicals, sprays containing DEET are among the most effective, the CDC advises. DEET is safe for pregnant women and for children to use.
And cover up with long sleeves and long pants, use screens and air conditioning.
The Aedes mosquitoes that transmit Zika like to live close to people, and the CDC advises keeping even the smallest containers empty of standing water.
Aedes species of mosquitoes don’t breed so much in open water as inside homes, in flowerpots, birdbaths, pet dishes, trash and small puddles. And they bite in the daytime, not at night.
Where’s the biggest risk?
Anywhere that has the Aedes aegypti mosquito — better known as the yellow fever mosquito as it carries that virus, along with dengue and chikungunya, also.
That means most of Central and South America and the Caribbean, the South Pacific, Africa, southeast Asia and the U.S. Gulf Coast. The Aedes albopictus mosquito, also known as the Asian tiger mosquito because of its distinctive stripes, can also carry Zika and it thrives in a wider variety of environments, including cooler climes.
The CDC has a county-by-county map showing where Zika may be the most likely in the U.S.
Where did Zika come from?
Zika originated in Africa and appears to have spread slowly until around 2013 and 2014.
It really took off in Brazil last year, and scientists are not yet sure precisely why. It could have to do with some genetic mutations that evolved, or it may be that it was noticed because it hit a big population of people who had no immunity to the virus, so that millions became infected very quickly.
What happens if I get Zika?
The most common symptom appears to be a raised rash. People also report fever, muscle aches and red eyes. Some patients report they felt really tired and sore, while others don’t remember any symptoms at all.
If you are pregnant or might be, it’s important to see a doctor right away and get tested. There’s no known way to protect a baby whose mother is infected, but doctors want to keep an eye on the pregnancy. Much of the damage Zika can do to a developing fetus is invisible until after the child’s born but if Zika has caused severe brain damage, it will show up on scans by the third trimester.
Men who have been infected need to remember the virus can stay in their semen for weeks or even months. People have also been infected via oral and anal sex with men. Men need to practice safe sex for at least six months after a Zika infection to be sure they are not infecting their partners. That means using a condom every time, the CDC and World Health organization say.
There's no cure for Zika infection but it usually clears up in about a week and doctors believe people are immune after that.
TODAY Health and Wellness editor Jane Weaver contributed to this report