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Florida Zika case may be first from mosquito inside U.S.

U.S. mosquito-borne Zika case?

Florida health officials are investigating what may be the first case of Zika virus in the U.S. transmitted by a mosquito. The patient does not appear to have traveled to a region with an outbreak of the virus.

The Florida Department of Health announced Tuesday evening that it is conducting an investigation into a possible non-travel related Zika infection in a patient in Miami-Dade County. But that's the extent of the information they would release.

Florida health officials said they're working closely with the U.S. Centers for Disease Control and Prevention and that it's very early in their investigation.

The case under investigation is one of more than 1,300 cases of Zika infection reported in the United States so far, but it is raising alarms because it doesn't appear to be travel related and may not have been sexually transmitted.

"All of those things have to definitely be ruled out," Dr. Aileen Marty, a Florida International University infectious disease expert, told CBS Miami.

"They are going to have to do a very careful determination of where the individual lives, where they work and where they have been playing for the last couple of weeks. We don't know the exact incubation period -- in other words, the time from when a person's body encounters the Zika virus within and when that person manifests the disease," Marty said.

If it is determined to be mosquito transmitted, Marty said those areas where the person could have come into contact with an infected mosquito will be thoroughly sprayed.

Mosquitoes: "The most murderous animal on earth"
Mosquitoes: "The most murderous animal on earth"

She said Florida has one of the best mosquito control programs and if Zika is identified there, it won't be the first mosquito-borne disease the region has had to handle. Small outbreaks of dengue and chikungunya virus have been contained in Florida in the past.

Health officials and have been predicting that Zika could start spreading within the U.S. this summer, with Florida and other gulf states especially vulnerable. "This could be a big deal," said CBS News chief medical correspondent Dr. Jon LaPook.

The virus could not have arrived in mosquitoes flying up from South America, he explained. "They only travel about a half a mile in their whole life. It would be from a person who was infected, say in Brazil, coming up here to the United States. Now there would still be virus in the person's bloodstream. Then an uninfected mosquito in the United States would bite that person, become infected and then turn around and bite an uninfected person and now you would have local transmission," LaPook said on "CBS This Morning" Wednesday.

When someone is bitten and infected, the Zika virus stays in the bloodstream for about a week. It may persist in other bodily fluids for longer, meaning sexual transmission could occur over several more weeks.

Symptoms of Zika infection include joint pain, fever, rash, pinkeye, muscle pain and headache. But only about one in five people infected with Zika show any symptoms.

The CDC is continuing to recommend that people take steps to protect themselves from infection, especially pregnant women who are at risk for giving birth to babies with a serious birth defect called microcephaly, where babies are born with abnormally small heads.

"Cover up, make sure that you use insect repellant, try to stay indoors, use air conditioning," recommended LaPook.

"The big next step here in the next couple of days is going to be to look at local mosquitoes which they are already doing to see if there are any local mosquitoes in Miami that have the Zika virus in them. And also to test people in the neighborhood and see if, somehow, they have become infected -- because remember, 80 percent of people who get infected have no symptoms. So it might already have started to spread by local mosquitoes without people knowing it," said LaPook, who spoke with a Florida health department official yesterday.

He said the reason the health department is telling the public even before confirming the case was locally-transmitted is that they are starting now to go door-to-door to test people in the area.

"People would have started asking questions, so they made this public announcement," LaPook added, explaining that they're trying to get ahead of the curve and be prepared.

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