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If pregnant, beware of travel to countries with Zika virus

Transmitted by mosquitos, the Zika virus can cause babies to be born with unusually small heads and brain damage. It has spread from Brazil to several countries and territories in the Americas, with a handful of cases confirmed in the U.S. Jeffrey Brown talks to Dr. Tom Frieden, director of the Centers for Disease Control, about an advisory that pregnant women avoid travel to affected areas.

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    Next: growing concerns over a mosquito-borne virus that is linked with birth defects and has moved into South America, the Caribbean and now the U.S. And, so far, there's no treatment for the virus.

    Jeffrey Brown has the story.


    The Zika virus has been known of for decades. But beginning last May in Brazil, it's taken a frightening turn, being linked for the first time to babies born with unusually small heads and brain damage, more than 3,800 cases to date.

    Zika is transmitted by mosquitoes. And government workers have been checking house to house in Brazil for breeding grounds.

  • MARCELO CASTRO, Health Minister, Brazil (through interpreter):

    We are in this battle, this fight to do this in a record time.


    In most cases, individuals who contract the virus show few or no symptoms. But the virus is spreading, already to a number of countries and territories in South and Central America and the Caribbean.

    There have also been a handful of positive tests confirmed in the U.S. In each of these cases, the patient or mother is believed to have picked up the virus abroad.

  • STEVE HUARD, Hillsborough County, Florida Health Department:

    The individual went to the doctor, had known about the Zika virus, let their physician know that they were in an area that had it. They tested, and came back positive.


    The CDC recently issued an advisory recommending that pregnant women avoid travel to affected areas and says those who have already traveled to such areas and are feeling sick should be tested for infection.

    I spoke about all this yesterday with CDC Director Dr. Thomas Frieden, and asked first how serious a threat he sees in the Zika virus.

    DR. THOMAS FRIEDEN, Director, Centers for Disease Control and Prevention: Zika is really new in this form, although it's been around, known since 1947. It's only in the past eight or nine years that we have seen outbreaks of Zika, and only in the past couple of months that we have seen this large number of cases of a serious birth defect in Brazil which appears to be related to Zika.

    That's why we're recommending that if you're pregnant and you're thinking about travel, check the CDC Web site to think about whether you want to go to that place or not.


    You're telling people right now, pregnant women, to think about postponing. You're not definitively saying don't travel to these countries yet?


    We're advising pregnant women not to travel to places that have Zika transmission, because there is just too much we don't know, so if it's possible to avoid that travel, that's important to do.

    For anyone who is in an area with Zika, pregnant or not, or if a pregnant woman goes to a place or is in a place that may have Zika virus spreading, it's spread by mosquitoes, and there are important things you can do to reduce your risk of getting a mosquito bite. You can wear repellent. That works. You have to wear it all day long, because these are mosquitoes that bite during the day.

    You can also wear clothing that has permethrin in it. These are both safe in pregnancy. You can wear long sleeves and long pants to reduce your exposure, and you can stay inside in air conditioning or screened spaces. All of these things really do reduce your risk of mosquito bites. But we are recommending at this point, until we know more, just to be safer, that pregnant women, if possible, avoid travel to places that have Zika virus transmission.


    Now, you have said several times there's too much — there is a lot we just don't know.

    Let's just go through what we don't, what we do know, because I gather that, until recently, most cases involving Zika were not very — considered very dangerous, right? Many of them had no symptoms whatsoever.



    We have generally seen as many as four out of five people who get infected by Zika don't know it. They don't have any symptoms. And among those who get infected, the symptoms tend to be mild and go away within about a week, a rash and fever and not feeling well.

    We have seen some reports of people who may have weakness or paralysis temporarily after Zika. Whether that's related or not, we still don't know. That's being investigated. But what's really concerning is this large number of birth defects that have been identified in Brazil.

    And studies in our CDC lab have identified that, in some of the infants and some of the miscarried fetuses, because there were miscarriages, we have identified the Zika virus. That doesn't say that it's the only cause or the cause of all of them. There may be other factors, nutritional or other infections, that are going into that, but this is a very unusual circumstance. It's very unusual that we identify a new virus that causes serious birth defects.


    There was a case reported in Hawaii of a baby born with brain damage. The mother in that case had lived in Brazil?


    That's correct. The mother had lived in Brazil, gotten Zika in Brazil, and then the baby, sadly, was born with a malformation or problems in Hawaii.

    And we have seen people, travelers coming back from areas with Zika, with Zika in the U.S. We have diagnosed a dozen so far in our laboratory. And this is not unexpected. When Zika is in a community, it can spread quite widely. But what we have seen is that it tends to be associated with one particular type of mosquito that is only in certain parts of the U.S..

    And in those parts of the U.S., with the use of mosquito repellent, air conditioning, screens, we haven't seen large-scale transmission with viruses with this type. But we're still learning more and working hard to learn more about this virus.


    But is it not likely to spread into the U.S., given the pattern so far, and as the weather warms up come spring?


    I don't have a crystal ball. I can't predict what will happen.

    I can tell you what has happened with other similar viruses. This is spread by the mosquito that spreads the dengue virus. And there are some parts of Florida and potentially some parts of Texas where we have seen transmission of that virus, so it's possible that that will occur.

    However, this virus is a little different, in that it mostly affects people, and so — and people only carry it for a few days. So how widely it will spread in an area where you're not seeing people without air conditioning, you're not seeing people otherwise, we don't know.

    But it is certainly possible that we will see cases in certain parts of the U.S. and possible we might even see clusters. But we don't predict that we would see something widespread, as we saw, for example, with West Nile virus, where you have a bird reservoir which can spread it and perpetuate it.

    But we can't say for sure. What we can say for sure is that, if you're pregnant, you would think twice before you go to a place with Zika. We advise you not to. And for anyone who is in a place with Zika or other mosquito-borne diseases, you can take practical steps to greatly reduce your risk of getting a mosquito bite, and therefore a disease spread by mosquitoes.


    All right, Dr. Thomas Frieden of the CDC, thank you so much.


    Thank you.


    The CDC also launched its latest anti-smoking campaign this week. We spoke with Dr. Frieden about its impact. And we will show you part of that conversation tomorrow.

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