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How Scientists Are Working To Eradicate Zika Mosquitoes


This is WEEKEND EDITION from NPR News. I'm Scott Simon. The World Health Organization predicts that up to four million people in this hemisphere could be infected with the Zika virus this year. The virus itself causes mild symptoms that can last less than a week, including fever or rash. The real danger is the possible link the virus has with birth defects if its contracted while pregnant. There is currently no known vaccine. So what, if anything, can be done to stop its spreading? Zika is transmitted by the same mosquitoes that carry dengue fever and yellow fever. Could health officials target those mosquitoes to try to halt the problem while a vaccine is developed? Professor Anthony James is a vector biologist at the University of California, Irvine. Thanks very much for being with us, Professor.

ANTHONY JAMES: You're welcome.

SIMON: So how do you go after specific mosquitoes?

JAMES: If you don't mind, the first thing I - point I'd like to make is that the mosquitoes that transmit the Zika virus are invasive species. So if we have a plan to eliminate them, we're not going to be doing any harm to the environment. And the people that I work with and - are interested in what we call genetic technologies to eliminate these insects. And the idea would be that we would develop some type of genetic strain that's similar to an insecticide but doesn't have the non-target effects that insecticides have.

SIMON: Forgive me for speaking this darkly, but how do you zap the right mosquitoes?

JAMES: We have developed technologies that allow us to put DNA into the mosquito species. This case, they are called aedes aegypti and aedes albopictus. And so we use microinjection techniques to put genes in there. And then when those genes are active they can actually cause the mosquitoes to die or be infertile.

SIMON: This is going to sound incredibly naive, but, I mean, you put a very tiny hypodermic needle in a mosquito, no, right?

JAMES: That's exactly right.

SIMON: You do?

JAMES: It's an extremely tiny hypodermic needle. The mosquito eggs that we inject are, for those of you in the metric system, half a millimeter long by one quarter of a millimeter wide. So they're really tiny.

SIMON: And how do you catch up with - I don't know - 500 million mosquitoes?

JAMES: So recently colleagues of ours working at the University of California San Diego have developed technologies that could rapidly move genes through populations. And so what we do is we have that mate with the mild mosquitoes and those genes will spread very rapidly through the population. So we use genetic tricks to get the genes to spread.

SIMON: And this is practical.

JAMES: We think it's highly practical, especially since all the other alternative technologies actually don't work. Our work was initiated to target dengue fever, which these same mosquitoes transmit. And we well know that dengue fever's still a major problem worldwide. And so we don't really have good technologies for that. So we have an opportunity here to essentially kill multiple birds with one stone - to use a poor analogy (laughter). But the Zika virus, Chikungunya and dengue fever are transmitted by the same mosquitoes. If we suppress those populations, we could have benefits for all three of those.

SIMON: And it's not enough just to spray on stuff from the drugstore.

JAMES: I would do that in the interim until these technologies become available. But as many people living in the more impoverished countries can't afford to constantly be putting on insect repellent, and so that is problematic.

SIMON: Yeah. How long could an effort like this take, Professor?

JAMES: Well, I think we're prepared to have strains ready before the end of this year. The question, of course, then is a phase program of testing them so that we show that they're safe and efficacious. But if we were to start now and had the appropriate efforts mounted for this, we would certainly see an impact in, say, three to five years.

SIMON: Professor Anthony James from the University of California, Irvine, thank you, sir.

JAMES: You're welcome. Transcript provided by NPR, Copyright NPR.