Mosquito breeding grounds are front line in fight against Zika

The Zika virus has been found in more than 25 countries and at least nine cases have been identified in Florida, prompting the governor to declare a health emergency in some areas. Mosquitoes are the main source, but officials say they are investigating a reported case of sexual transmission in Texas. Gwen Ifill talks to Michael Osterholm of the Center for Infectious Disease Research & Policy.

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    Anxiety over the Zika virus continues to build. In Florida, where there are at least nine cases of the illness, Gov. Rick Scott declared a health emergency in four counties today, including Miami-Dade. Zika has been found in more than 25 countries in the Americas and Caribbean.

    Nearly all cases come from mosquitoes. And the CDC issued a new travel advisory today for Jamaica. At the same time, public health officials say they want to learn more about a reported case of sexual transmission of Zika in Texas.

    We look at some of the central questions with Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.

    Thank you for joining us.

    How worried should we be with these new reports every day, these new classifications every day of this new virus?

    MICHAEL OSTERHOLM, Director, Center for Infectious Disease Research & Policy: Well, first of all, the fact that there's been a case now documented of sexual transmissions doesn't surprise us. That's already happened before.

    The question is, how often it will occur? And at this point, we don't have any evidence it's a frequent occurrence, but clearly for those who travel from the United States to one of these affected countries and a male coming back having sex with his female partner who either may be pregnant or could become pregnant is a concern. And in that sense, that's what we need to be most worried about.


    How significant is a WHO call or declaration of emergency in this case?


    Well, first of all, to really understand this concept of emergency, what it really does is, it just helps prioritize the kind of resources and the importance to the world that this is.

    It shouldn't mean that people should panic or that people should somehow do something very, very different. What we need to do — and we know how to do it, actually — is what we do, what we call source reduction for the mosquitoes in the Americas, meaning let's get rid of the breeding sites.

    This particular mosquito is really what I call the Norway rat of mosquitoes. It lives with humans. It loves to life in the human home. It breeds in water bodies that occur, for example, in a pop cap or a piece of discarded tinfoil, non-biodegradable material, tires.

    If we clean up the solid waste, the garbage, really, around our communities in those counties and countries where this is occurring, we can have a great impact on the transmission of this virus by this mosquito.


    So, focusing on the mosquitoes is what they call vector control. How much should attention be spent on that and how much on developing a vaccine?


    Well, first of all, there is no one answer. It's all of the answers.

    You want to do as much as can with the source reduction, meaning get rid of where they breed. This type of mosquito is very different than, for example, the one that causes malaria, in most instances, which might be in large bodes of water, in rice fields and so forth.

    This is really breeding in very, very small bodies of water, as I said, such as might be in a discarded wrapper, inside a tire. The second thing is, you want to make sure that you can kill the adults who do that, but that by itself is not enough. That's often a great photo opportunity to show someone out with a spraying machine, but that is truly not it.

    You want to do all of that, plus you want to work on vaccines. You want to look at, can you use genetically modified mosquitoes? So, all of these are things that should be brought to bear. And I think the point that has been missed here in this country is that this mosquito has already been causing very serious death, disease and death, in South America, Central America, already, with dengue and another virus called chikungunya.

    And so by taking care of the Zika virus, we actually end up taking care of all these other ones.


    So this is similar, rather than different, from something like the dengue virus, which last we were talking about that was in 2013, I think?


    Right, exactly.

    And, as you know, on this very program, there has been discussion about how many thousands of people have died, how many people had serious illness. In a sense, if you take care of dealing with any one of these viruses, you take care of all of them.

    And so while — what has happened really is because of the issue with microcephaly, and this very, very horrible image of these children with these very small heads, the world has now paid attention. This has now become a photo opportunity kind of crisis.


    So, now that the world is paying…


    And that wasn't the case with dengue.



    So, now that the world is paying attention, what are the questions that should be getting asked which are not yet?


    Well, first of all, we have to find out just how bad this disease really is, meaning in terms of number of cases.

    There's no doubt that microcephaly, or these small heads, in newborns, as — and small brains, as well as the Guillain-Barre syndrome, this type of paralysis disease, is occurring because of Zika. What we have to understand is in fact how frequently it's occurring, where it's occurring.

    Right now, much of Brazil has not been impacted. So, when we come up with these country-wide numbers, it doesn't mean much. What we have to do is look at where it's going to unfold.

    Just as an example, the chikungunya virus, which came into St. Martin in December of 2013, is still unfolding across the Americas. Expect the same thing with the Zika virus. For the next two years, we are just going to just see this continue wave after wave to go through these communities.


    Dr. Michael Osterholm of the University of Minnesota, thank you very much.

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