MS. DIANE REHMThanks for joining us. I'm Diane Rehm. U.S. health officials say the time is now to step up efforts to protect against the Zika virus. The mosquito-borne illness is spreading rapidly in South America and the Caribbean and can lead to babies being born with abnormally small heads and brain damage. Joining me to talk about what we're learning about this virus, what it might take to contain the threat, Dr. Anthony Fauci of the National Institutes of Health, Maggie Fox of NBC News.

MS. DIANE REHMJoining us by phone from Baltimore, Dr. Jeanne Sheffield of Johns Hopkins Medicine. Do join us, 800-433-8850. Send your email to drshow@wamu.org. Follow us on Facebook, send us a tweet. And welcome to all of you.

DR. ANTHONY FAUCIGood to be here.

MS. MAGGIE FOXGreat to be here.

DR. JEANNE SHEFFIELDThank you.

REHMDr. Fauci, the Obama administration has asked for $1.9 billion in emergency funds for the Zika virus. Why?

FAUCIWell, the fact is we need it and the reason is that there is not designated Zika money. So now, we're left with a situation where -- when I say "we," we're talking about multiple agencies, the NIH, the CDC, the FDA, USAID, all have a role in the response both internationally and ultimately domestically and we need the $1.9 billion that the president has asked for. We're moving along anyway, but we still will not be able to do the job that's essential if we don't get that $1.9 billion.

REHMBut what will you do with that $1.9 billion?

FAUCIWell, for the NIH, we will be doing vaccine development. We'll be doing drug screening. We're doing what's called pathogenesis and natural history studies where we're trying to determine the scope of this disease, why we have such neurological abnormalities not only in the fetuses of infected pregnant women, but also we're seeing some other complications that we're seeing in people who are not necessarily women who are pregnant, but others who are developing these unusual difficulties.

REHMLike what?

FAUCIWell, for example, we don't know how many of these there are, but there are case reports of new interesting kinds of syndromes, we call acute myelitis, which involves the spinal cord, meningoencephalitis and there's this couple of case reports of a disease called acute disseminated encephalomyelitis. Again, there are only a few cases, Diane, so I'm not sure what the extent of it's going to be, but those little things that you see get you concerned that we're just starting to see the tip of what might be more difficult situations.

REHMSo what has happened in the last few weeks regarding Zika that creates this sense of urgency?

FAUCIWell, a number of things. First of all, the realization that there's relatively little doubt now that the deleterious effects that we're seeing in fetuses are due to the direct effect of the virus. There was some talk about maybe indirect things, co-factors. Very clearly now a number of studies, not only in following these pregnant women where we're seeing an array of abnormalities in the fetuses, but also when you do animal models, in vitro test tube studies showing this. The other thing, the CDC is playing a major role in this not only in South America, but also in the Caribbean.

FAUCIPuerto Rico is really quite vulnerable and the CDC is really putting a full court press on now in trying to address that as well as situations, potentially, here in our own United States, in the own continental United States.

REHMDr. Anthony Fauci of the National Institutes of Health. Maggie Fox, as senior health writer for NBC News, do you think that now people are becoming more aware of Zika and more concerned?

FOXWe're definitely getting more and more questions from people, more interest in the Zika stories. People are starting to ask, wow, I'm going to the Caribbean this summer, am I going to be affected by this? Wow. I'm thinking about getting pregnant. Is it going to affect me here at home? What happens if someone comes back from their vacation to South America or the Caribbean and brings the virus into my community, my neighborhood? Will it affect me?

FOXAs we know, Americans, like everyone else, are worried about themselves. They can hear about a virus that's spreading across Brazil. It seems far away and it seems like it's really not going to affect them. I think the rapid spread of the virus across all of the Americas is starting to catch people's attention and they're saying, oh, could it come here? We have mosquitoes here in the summer. Are they going to bring the virus to me? It's an interesting question and the CDC's recently updated its maps and said, well, actually, the one species of mosquito that's absolutely certain to carry this virus is actually a little more common and a little more widespread than we thought it was.

FOXIn fact, we've found it as far north as San Francisco, Kansas City, New York City. So this summer, it's possible that someone could come back with Zika virus, perhaps infect a mosquito and there could be local outbreaks I think and I think Dr. Fauci will confirm this. There won't be widespread outbreaks in the U.S. like there are in Brazil because of the way people live, but what we're trying to do is answer the questions that people have about how likely it is to affect their communities here in the states.

REHMTell me about the concerns you may be getting from people planning to attend the Olympics in Brazil.

FOXLots and lots of questions about the Olympics. People are really worried about that. If I go down there, will I get it? And not just people who might be women who are planning to get pregnant who might get pregnant because there are also some troubling reports, as Dr. Fauci mentioned, of other effects that the Zika virus is having on adults like Gilliam Barre Syndrome, which is that paralyzing syndrome that you can get from any virus or any bacterial infection.

FOXIt's rare, but because Zika is affecting so many people, we're seeing it very commonly. And then, some of these other rarer effects, the brain inflammation, the spinal cord inflammation that can really put you in the hospital for a long time with serious side effects, too.

REHMMaggie Fox is senior health writer for NBC News. Turning to you, Dr. Sheffield, tell us about the guidelines you've been working for for women who are thinking about getting pregnant or are already pregnant.

SHEFFIELDSo the Centers For Disease Control and Prevention took the lead on these guidelines actually back a number of months ago and the American Congress of OB/GYN and the Society For Paternal Fetal Medicine have all kind of joined with the CDC to develop guidelines both for people that are planning on travelling and also those that are pregnant and are -- have already travelled. And these guidelines address everything now from men and women who are considering becoming pregnant or getting pregnant and thinking about travelling to pregnant women that have already travelled or pregnant women whose partners have travelled and then exposed the mother of their child.

SHEFFIELDSo these guidelines now extend all across the reproductive age group in women and men and they're very clinical -- are clinician friendly so that both patients and clinicians can read these guidelines and get a good feel for how to manage their contraceptive choices.

REHMSo it's no longer just the women we're worried about. It's the men as well because if infected, they could then transmit that Zika virus to a woman who may become impregnated and bear the consequences.

SHEFFIELDAbsolutely. So once sexual transmission was confirmed and we've now had a number of cases that have been reported, then the male became the "vector." Instead of just the mosquito, now we have the male that could potentially infect a pregnant woman or a woman considering becoming pregnant at which point we then had to start considering guidelines for how are we going to deal with a male that travels and comes back who has a female partner who is interested in becoming pregnant.

REHMSo what kinds of tests are available for someone who thinks she or he may have contracted the Zika virus?

SHEFFIELDSo if they think they've contracted it and they've had symptoms recently -- we were saying with seven days. We now know that there's at least one case report of a pregnant woman whose child was infected whose blood testing actually stayed positive for longer than the seven days. But if you are acutely ill or have been ill recently, the RTPCR, this polymerase chain reaction, can actually test for the RNA of the Zika virus. It's a good test, but the problem is it does become negative as the viremia or the Zika virus clears from the body.

SHEFFIELDOnce the virus has cleared, usually by that time the woman or the man has started to develop an IGM antibody response and that is a test that the CDC has available, several states now in the country have available for testing and then finally, there is a confirmatory test that is available through the CDC, a plaque-reducing neutralizing antibody test that is -- it takes a little time to get back, but it is available for confirmation.

REHMGo ahead, Maggie.

FOXWell, I'd like to ask, because isn't this one on the issues -- I think both Dr. Fauci and Dr. Sheffield can tells about and I'm curious to know -- isn't this one of the issues with the funding, that we need to have more of these tests?

FAUCIWell, we need more and better. The issue is that we, the CDC and others are working a more specific test because one of the tests, the test for the antibody, if you're also exposed to dengue, that is has cross reactivity with dengue so you don't know precisely. If you're looking for the virus, Diane, the virus PCR test that Dr. Sheffield mentioned is quite specific. You'll know if you are infected. The real critical question is was I infected a little while ago and that's the one that's non specific.

REHMDr. Anthony Fauci of the National Institutes of Health. Short break here. Your calls, your comments, I look forward to hearing from you.

REHMWe're talking in this hour about the ongoing concerns regarding the Zika virus, how it is spreading, how very much the CDC is concerned about creating a vaccine that could in fact help people to avoid the Zika virus. The president and the NIH have asked for $1.9 billion additionally to help deal with the issue. So far the Congress has not acted.

REHMHere's an email from Laura in Liberty Township, Ohio. She said, I've heard and read that the actual Zika virus is not necessarily the culprit of infant malformations but rather the toxic larvacide being used in water resources. Why aren't we hearing more about this, Dr. Fauci?

FAUCIWell, Diane, it's just not true. That's not the case. The evidence that the virus itself is the direct cause of the fetal malformations is now becoming extraordinarily compelling.

REHMSo who's writing about this stuff? Where's it coming from?

FAUCIYou always hear things like that. Whenever you -- whenever you have a situation that gains public attention like this, there are always people that come up with alternative theories, essentially based on no evidence. If you look at evidence-based types of conclusions, the evidence that it's the direct effect of the virus itself not only on the developmental aspects of the fetal brain but direct toxic and destructive effects on the fetal brain and nervous system.

FAUCISo the data are now becoming so compelling that soon there'll be an absolute conclusion that there's no doubt it's the virus itself.

REHMAll right, Dr. Sheffield, talk about the kind of damage that the Zika virus does to the brain.

SHEFFIELDSo when the initial reports started coming out back in October, November, December, we were hearing about microcephaly or a small head related at gestational age. We also started hearing then about calcifications in the brain. Well, since that time we have discovered that there are multiple neurologic abnormalities. Multiple studies have shown that if you look specifically at the brain development, it is abnormal, there is destructive processes going on so that if you look at the brain structure, it is actually abnormal in a large percentage of the cases.

SHEFFIELDSo it's not just a small head or calcifications in the brain. There are multiple abnormalities now found in the nervous system, in the actual brain structure.

REHMAnd are we talking about the risk confined to the first trimester?

SHEFFIELDYou know, a lot of viruses, the infections in the first trimester are the biggest problem. You get infected in the first trimester, as the brain is developing or as the body is developing, and that's when you see a lot of the abnormalities. Zika appears to be different. The data that is coming out is showing that we are seeing abnormalities in the brain regardless of the trimester that they're being infected, and some of that may have to do with the fact that this does appear to be a disruptive or a destructive process. It doesn't just cause problems as the brain develops, but even after structures are formed, it looks to be that if they get infected, there may actually be true destruction of some of the cells.

REHMDr. Fauci, what about non-pregnant women, and what about the age factor? What are the differences?

FAUCIWell, when you say non-pregnant women, I think you would treat non-pregnant women the same way you would treat an adult in the sense -- except that there's no evidence that women have sequestration of the virus following the infection. We do know that the detection of virus in a pregnant woman is now, particularly a couple of the case reports, is now perhaps even considerably longer than we thought.

FAUCIAnd there was one recent case where the virus was actually detected for weeks. But if you have a woman who's non-pregnant, there doesn't seem to be any difference, except unlike men, which can sequester the virus in the semen. There doesn't be any evidence that there's women sequester it for a period of time when they're not pregnant.

FAUCIAs far as age factor goes, it doesn't seem to be any major difference that we're seeing now between children and adults.

REHMBut Maggie, if one is, say, in her 50s or 60s and becomes infected with the Zika virus because she's been bitten by this particular mosquito, what happens? What's the effect on her?

FOXThere haven't been a lot of studies published on that yet, and that's a great question. People are looking back at other outbreaks in other places, like in Yap in French Polynesia. And they found that when the virus moves into a population, almost everybody gets it. It's amazingly common. But hardly anybody actually shows the symptoms. I don't think anyone's actually looked at that directly, or at least they haven't reported their results on what's happened in Brazil. It's called the attack rate, and the symptom, you know, the number of people who have symptoms.

FOXBut in the previous outbreaks, most people, 80 percent, didn't even know that they'd been infected. They had the antibodies to the virus, they had evidence of past infection, but they had not remembered having a fever, they hadn't remembered having a rash. The people who have studied what it does do, I think it's 90 percent of people have a rash. If they have any kind of symptom at all, they have a rash. They also may have a fever, they may have headaches, which I guess goes with the fever, and the muscle aches. Not much else than that.

FAUCIIt's generally as mild a disease -- as we mentioned in the beginning of the show, there are now these individual case reports about dire neurological consequences in adults, but for general, if you look at the total cohort, it is generally a mild disease with very little mortality associated with it.

REHMSo you're not talking about the entire population. That's what I want to zero in on. It depends on where you are in the life cycle as to how badly you might be affected by it.

FOXThere's a reason that people ignored Zika. It seemed to be a completely harmless virus for -- you know, since 1947, when it was first identified, nobody ever associated it with really making people sick. It was one of those things, you might get a rash, probably not even that, it's not even going to make you sick. So the new results that are being found are stunning people, and as the scientists keep saying over and over again, the more we find out about it, the more it scares us. It's creepy.

FOXIt could be just because it is all of a sudden affecting millions and millions of people, and so you're seeing these very small effects looking big because if you get one percent of a million people, that's a lot of people.

REHMAll right, and joining us now from the Florida Keys is Phil Goodman. He's chair of the Florida Keys Mosquito Control District Board. And welcome to the program, Phil. I know your area of Florida is considering introducing genetically modified mosquitoes to bring down the population of this particular kind of mosquito. Explain what's been proposed.

MR. PHIL GOODMANYes, Diane, good morning. What we have -- and this started about seven or eight years ago. The genetic modified mosquito was introduced to the Florida Keys, the concept, because of Dengue Fever. You know, we had had outbreaks here. We were the first, really, outbreak I think in 40 years in the U.S. of Dengue Fever in 2009 and '10. And so, you know, and the current technologies used to combat the Aedes aegypti mosquito are not very effective.

MR. PHIL GOODMANYou know, some of the better known insecticides, pesticides, the mosquito has become resistant to that over the years. The way the mosquito lives and breathes, and it's very difficult to hit it with sprays from helicopters and airplanes like we do. And so, you know, we needed new technologies. And so the genetic modified mosquito was introduced to us. We've been studying it here now for over six years. And, you know, it's been -- we presented it to the FDA for -- to have them to study it. They've been studying it for several years and recently came out with a finding of no significant impact, an initial finding, where the CDC, the EPA and the FDA looked at this, and they found no significant impacts to prevent the test.

MR. PHIL GOODMANAnd now we're in a 60-day public hearing period, where we're getting comments from the public, or the FDA is, and they'll be looking at that. It has 30 more days left on this period. And then the FDA will have time to look at this and make a determination whether more studies are needed or whether they have all the information they need to offer a final finding of no significant impact, and then, you know, we can make preparations to proceed with the trial.

REHMAll right, and I gather it's already being used in Brazil. Is that correct?

GOODMANYes, it's been being used there for some time with very good results. Everywhere this has been used and studied, within six to eight months you see a significant drop of the Aedes aegypti mosquito down to within, you know, 60 to 80 percent reduction, and then continued for a few more months, you usually get it down to 90 percent or 95 percent, which the experts believe it takes this -- this decrease to effectively prevent the spread, the local transmission, you know, should we get it here.

REHMAll right, I have an email here from Michael, who says I'm concerned the genetically modified mosquitoes introduced to Brazil in 2012 are responsible for the genetic defects we see today. Can you explain why this is not possible, although one of every 1,000 genetically modified mosquitoes is fertile?

GOODMANWell, you know, it's like we said earlier, you know, alternate theories always come out, something like this, based on no evidence, and there's really no evidence to prove -- to prove this. It's just not accurate. And, you know, there -- you know, we mainly release only male mosquitoes with -- that's the intent here, and the male mosquitoes do not bite. The female mosquitoes do bite, and because of the sorting -- the way these females and males are sorted from each other after this process, there's like one in 10,000 females can be introduced.

GOODMANAnd this has been studied by the CDC, the EPA, the FDA and Oxitec, who developed this, a lot of studies that show that, you know, this transformation is not in the saliva so that there is really no chance to pass this gene along. Even if it were in the saliva, it's found to be non-allergenic, non-toxic, and so, you know, the finding -- the FDA did a lot of studies on this based on the environmental, the draft environmental assessment that was sent to them from Oxitec, and, you know, they also include in their initial findings that there -- you know, there is no negative impact that they're seeing to the environment, to people or to other unintended species.

REHMSo if the FDA continues with that no significant effect position, how soon would you think you might introduce this genetically altered mosquito into the Florida Keys?

GOODMANOkay, now there's -- a few things have to happen. You know, once, if we do get a final no environmental impact statement from the FDA, then the board will vote. We voted -- the board has voted unanimously in the past on several different phases of this process. We have one phase left, which is more or less how the test will be administered and evaluated. So about 10 percent of it has to be approved by the board.

GOODMANOnce the board of commissioners approves this, after there is a final finding of no significant impact, then we could start the trial pretty soon because we have already -- you know, as part of the process to get to this point with the FDA, we had to establish a laboratory in one of our facilities that we can bring eggs in from -- that have had this modification.

REHMI see.

GOODMANAnd rear the mosquitoes to release them. So -- and that's already been approved. The CDC, the FDA and EPA have approved our laboratory.

REHMAll right.

GOODMANAnd so we are quite a ways into it, should we get approval. But, you know, we're still also very interested in what the public has to say.

REHMSure.

GOODMANSo we're going through a lot of this, as well, trying to educate the public, and they're -- and not everybody is a believer in this.

REHMRight. All right, and you're listening to the Diane Rehm Show. Maggie Fox, I know you wanted to comment.

FOXWell, I just want to point out that this is like the larvacide fear. People are afraid of genetically modified creatures. They're afraid of genetically modified food. The larvacide in the water question is -- has actually come up a lot. It's partly because the Internet has given people voice that didn't really have voice before. You couldn't block these comments.

FOXAnd they're not completely illogical. They're not based on any actual evidence, but the logic behind is a larvacide affects a developing mosquito, the genetic modifications of the mosquitoes make them lay dud eggs. This has to do with developing babies. Why can't it also be affecting pregnant women with developing babies? On the surface, it sounds logical. But when you talk to the researchers who have been watching this, they're not stupid. They know what evidence to look for. They've looked for this kind of evidence, and they haven't found any.

FOXWhat they have found is the Zika virus in the brains of these babies who have miscarried with the brain damage and active signs of the infection. So we spend a lot of time debunking these fears, and the genetically modified mosquitoes have also not been linked with any human effects.

REHMDr. Sheffield? Have we lost the contact?

SHEFFIELDOh sorry, I am back. Sorry, I had you on mute for a second so I didn't interrupt the show. I think we are all becoming very comfortable with the fact that the evidence is there. The virus is what is causing the problems in the neo-nates. It is not the larvacide, it is not the genetically modified mosquitoes. I'd like to reiterate, it has been found now in the tissues of these affected infants. And so we are -- there is more and more and more evidence being obtained showing that it is the virus itself that is causing the problems.

REHMAll right, and Phil Goodman, very quickly, if the FDA does not go forward, what's your alternative? What are you doing right now?

GOODMANOkay, you know, we have -- you know, for this mosquito, you have to have a strategy for the Aedes aegypti mosquito, which carries the Dengue and the Zika and other -- and Chikungunya. And so what we're doing now, we've got a lot of tools that we're using. None of them are that effective, but we're going house to house, we're, you know, trying to be sure that we're educating the people to dump out their water because this is what breeds Aedes aegypti mosquitoes around your home. We are also using larvacide. We're doing limited pesticide -- adulticide, but we're looking also at new technologies.

GOODMANYou know, there's the -- there's several new technologies that are coming out now.

REHMAll right, and I'm...

GOODMANThe one in the forefront is the genetic modified, but there's others that we're looking at as well.

REHMAll right, Phil Goodman, chair of the Florida Keys Mosquito Control District Board. Thank you so much for joining us. Your calls when we come back.

REHMAnd welcome back. Here's an email from Mike in Oakridge, Tennessee. What is known about the effects of Zika on infants and toddlers infecting after birth? Dr. Fauci.

FAUCIThere's no evidence that there's any more significant effects on infants and babies who are born and infected after they were born. There's a really interesting issue brought up regarding our discussion about mothers who are infected during pregnancy and babies who might not have the gross structural abnormalities that you might see. You still need to follow babies to find out if there are subtle effects that were from the infection while they were in the womb after birth. Because what you usually see when you congenital abnormalities, some are very gross.

FAUCIThat you could structurally relate, but there may be some subtle findings in babies who were -- whose mothers were infected, but as far as a baby being infected directly after birth, there's no evidence that that is anything different than what we see with others.

REHMAll right, let's go to Norman, Oklahoma. Hi Jane, you're on the air.

JANEHi. I'm a Tropical Ecologist, working mainly in Panama. And last year, we experienced the second driest year on record due to El Nino. And I'm wondering, is anyone wondering how events like El Nino are affecting the spread and populations of mosquitoes and maybe increasing or decreasing their spread?

REHMMaggie.

FOXThat's such a great question. It's a question we're asking too, because it's not obvious. In past outbreaks, when I was covering the West Nile virus outbreak, I talked to a lot of mosquito experts and they said, you know, it's not so obvious that a thunderstorm leads to an explosion. Sometimes dry seasons can concentrate the mosquitoes, but I think it depends on the species of mosquito too. Evidently, some of the money that had been going to mosquito research has dropped off and people have neglected in recent years the studies on what happens to mosquito populations as climate changes and even as weather changes. And that's one of the things some of the experts are asking for.

REHMAnd...

FAUCISuffice it to say, that weather can have a positive or negative effect. You can't make a determination that because the weather does this -- you could have a situation where it prevents mosquitoes from breeding well. And changes in weather can promote mosquito breeding. It really depends on the particular type of weather change and the mosquito in question.

REHMAll right, here's a question for you, Dr. Sheffield. Evan in Michigan says, my sister is planning on going to Guatemala this summer. I've heard the virus can cause abnormalities up to years after one contracted the virus. My fiancée and I are going to be near my sister a lot this summer. Is there a possibility she could be bitten and then I or my fiancée get bitten and contract the virus? We live in Michigan. My fiancée and I are planning on trying for kids within the next two years.

SHEFFIELDSo I think there's a couple of comments in there to address. One is what we have been telling people based on what evidence is available is that once they contract the virus, their symptoms resolve and they wait a certain amount of time, whether it be the eight weeks in an affected female or up to six months we're saying right now in an affected male. Beyond that, we don't believe there's going to be any long term effects. Unless there's, you know, Gilliam Barre Syndrome or something like that developing.

SHEFFIELDBut when you're looking at transmission to an infant or to a fetus, the -- once the woman has cleared the virus, there should not be long term risk to either that pregnancy or a subsequent pregnancy. The chance, it was mentioned a little bit earlier, the chance of coming back, being infected, so having the virus circulating through your body, getting bitten and having that mosquito then bite somebody else and they would get infected is feasible, but it is a very, very low possibility.

SHEFFIELDAnd he mentioned he was in Michigan. That mosquito, as far as I know, I've seen in revised maps, I don't remember seeing him going all the way up to Michigan. So, the risks are incredibly low.

REHMBut they are in New York. They are in New York, I gather.

FAUCIYeah, I mean, if you look at the map, the revised, updated map of Aedes Aegypti, it is much more expanded than what it originally was. Can I just comment about what you were saying and I think Dr. Sheffield made a very good point. That's probably the most frequent question we get asked. I certainly get asked that. I'm a woman, I'm going to go down to South America or the Caribbean or what have you. And if I get infected, is that going to affect my pregnancy that I want to get -- I want to get pregnant eight months from now.

FAUCIWe're planning, next year, to have children. And that's the reason, if you look at the guidelines, is that if you are a woman, it's an eight week period following return. Because you could have been infected sub-clinically, where you didn't know you got infected or what have you. If it's a man, the recommendations are six months with protected sex. So, if you come back and you could have been infected there, wait six months. Either no sex or constant and consistent use of a condom.

FAUCIBut the women are the ones who are calling up and saying, you know, I might want to get pregnant next year. Should I just completely stay away from this region?

REHMYeah. Yeah.

FAUCIAnd that's what the eight week waiting period is.

REHMTell me about concerns for the athletes who are going to Brazil, Maggie Fox.

FOXWell, we asked the question, you know, will there be athletes who could be pregnant while they're competing? And you kind of think, oh my gosh, who would compete in the Olympics if you're pregnant, but in fact, a lot of young women compete in the Olympics and they're at reproductive age. And they might be pregnant without even knowing it. So, we know the US Olympic Committee is really recommending to its athletes that they practice safe sex. You've got a lot of very fit, very active young people all together in the same place at the Olympics.

FOXBoth the spectators and the athletes. And things are going to happen when you get people in their 20s at the prime of their lives. And there are some concerns about this, that some of the young female athletes may end up getting pregnant while they're at the Olympics.

REHMLet's go to Justin in Dania Beach, Florida. You're on the air.

JUSTINHello. I just wanted to highlight the fact that Phil Goodman mentioned that the FDA is going to be analyzing data, provided by Oxitec. When they make the determination. And as a Florida resident, I wanted to voice my opposition to the release of these genetically engineered mosquitoes. I invite everyone to Google or look up horizontal gene transfer and then take this information into consideration when deciding if it's a good idea to release mosquitoes that are genetically engineered to self-destruct into our natural environment. And that's it. Thank you.

REHMMaggie.

FOXThat, that is a common fear that we're hearing and lots of people have Google at their fingertips. The hard thing to sort out is what's good information and what's not good information.

REHMIs the company that genetically modified the mosquitoes the same company that supplied the information to the FDA?

FOXThat is true. The FDA does rely on information that's provided by the company. They do have a lot of their own labs and they do a lot of their own tests. On the genetically modified mosquitoes, they are relying on Oxitec's information. They are, however, working closely with Oxitec too, to make sure that that information is accurate. There's a lot known about genetically modifying plants, animals, all sorts of things.

REHMCertainly.

FOXIt's well understood, there's a whole national institute of genomic research that that's all they look at. They understand how that works. They understand how gene transfer works. There's no evidence that an insect that's been genetically modified can pass on that genetic modification to a human being by biting them.

REHMAll right, let's go to Ranada in Boca Raton, Florida. You're on the air.

RANADAHi. Good morning, Diane.

REHMHi.

RANADAI have a question.

REHMSure.

RANADAI was born in Brazil and raised there. I do (word?) that while infections are widely spread throughout Brazil, the microcephaly cases are heavily clustered in the northeast region, which has historically been exposed to precarious conditions from like poverty to lack of infrastructure. Sanitary infrastructure. So the question from me is not the fact that Zika is related to microcephaly, but what is the relationship between the infection and the social environment. The social political environment and the geographic environment that makes Zika more dangerous to certain populations.

REHMAll right, Dr. Sheffield.

SHEFFIELDSo, I think that is a fantastic question. And it's something that we've actually been talking about are what are -- one, what are confounding factors? So, was -- especially initially, when we were looking at this, was it just Zika virus or was it co-infections with Dengue or Chikungunya. Was it some other environmental factor on top of the Zika virus infection? And so, that was something that was addressed very early on. The other point you made, which I think is an excellent one, which is the social factors.

SHEFFIELDSo we know that this virus is transmitted by a mosquito. Mosquito control is something that much more widely available in developed nations. So when we're looking at nations that don't have -- that have standing water or more commonly standing water, don't have air conditioning and screened-in porches. Don't have the DEET or the Permethrin available to them. Those are the countries that are going to have more problems. Or the areas that are going to have more problems. And so, I think you made two very good points.

SHEFFIELDOne, are there confounding factors? We're leaning more and more towards it's probably just a Zika virus, but, you know, we have talked about that quite a bit. And then you're other point of other confounding factors, such as social influences is a significant one.

REHMAnd a tweet from John, Dr. Fauci, who says, after the initial Zika infection, do people become vaccinated or immune against further infection?

FAUCIYeah. If it acts like other types of similar viruses, other types of flaviviruses and other related viruses. You would expect that there would be immunity. We don't have any evidence that there are multiple sub-types of Zika, the way we have with Dengue in which you have four separate serotypes. So right now, you can make an assumption that at least in the short range, there would protection. The durability of that protection, I think, would require study over a long period of time.

FAUCIBut there's evidence based on experience with other viruses that you would expect when you have a virus that doesn't have multiple sub-types, once you're infected that you are protected against subsequent exposure. But we have to prove that. We have to make those decisions based on evidence. That's why there'll be long range studies to look into the future after people have been documented to have been infected.

REHMSo, here in this country, Maggie Fox, where are we getting reports about Zika? We've heard from Mr. Goodman in Florida. What, Texas? You've got other southern states.

FOXWell, there's two factors here and it goes to the question also from the woman about social factors. All along the US south, there's a chance for Zika transmission from mosquitoes because people live outside. They -- in Key West, people don't have air conditioning. They like having their windows open. In Puerto Rico, people don't necessarily have screens and they have these open eaves that let the mosquitoes get into their house. And these mosquitoes live in houses. That's also why most of the continental United States is not vulnerable to widespread of Zika virus.

FOXBecause the mosquitoes don't live in air conditioned homes. They can't even get there. And they don't live in the parts of the country anymore that most people live in. The other factor is travelers bringing it back and that's getting people mixed up too, because they'll hear oh, I live in Michigan, I heard there was a case in Michigan. But that's a traveler bringing it back. And the other factor is that the mosquito doesn't bite you and then bite the person sitting next to you and transmit the virus. The virus has to live inside the mosquito for a while.

FOXSo unless the mosquitoes are living and breeding and brooding the virus in their bodies, they're not likely to pass it along either.

REHMAnd you're listening to "The Diane Rehm Show." Dr. Fauci, you wanted to add to that.

FAUCIYeah, well, the issue of what people get confused about numbers. If you look at the number of travel cases, it really relates a lot -- when Florida has a lot of travel cases because that's a jumping off point back and forth between the Caribbean and South America. California has a lot of travel and New York City because they're very populated cities. And states within those -- within that region. But what we're concerned about is what we've seen with Dengue and with Chikungunya. And when we say we likely will have local outbreak, I hope we don't.

FAUCIBut I would not be surprised, Diane, that we will see as we get into the exuberant mosquito season, as we get into the summer, that particularly along the Gulf coast, in Florida and Texas where we did see, in Florida and Texas, Dengue local outbreaks. And in Florida, a Chikungunya local outbreak. When you get a local outbreak, you try your best to prevent it from becoming sustained and prevent it from becoming disseminated. And that's what we were successful in doing with Dengue and Chikungunya.

FAUCISo we hope now that the efforts that are put into mosquito control as well as the conditions in those states that if we do get a local outbreak there, we'll be able to contain it and prevent it from becoming more spread.

REHMSo, if I, at my age, which is long past potential for pregnancy. I'm going to, say, the Florida Keys, where they're concerned about these mosquitoes, what do you advise, Maggie?

FOXWell, I don't advise anything, but the people I talk to are advising that you really don't want to get bitten by a mosquito anyway. They pass on all sorts of nasty stuff, not just Zika, but there is Chikungunya around, there is Dengue around. You should use an insecticide and DEET is evidently the very best insecticide at repelling the mosquitoes from biting -- it's not an insecticide, it's a repellant. It keeps the mosquitoes from biting you. People are scared of DEET. People are scared of insecticides. It makes them nervous.

FOXBut there's been a lot of testing on DEET and the CDC says, it's safe for everybody down to six month old babies. It's safe on pregnant women, it's safe on older people. They also recommend that you wear long sleeves, stay inside, stay inside the air conditioning as much as you can. Do what you can to avoid being bitten.

REHMDr. Sheffield.

SHEFFIELDSo, that is my -- that has been my strongest point to my patients that are coming to me saying, I'm planning on travelling. Is, if you have to travel, understand that DEET and Permethrin used in an EPA registered dosing is absolutely acceptable in pregnancy. We would much rather they use one of the EPA registered repellants than one of the other non-registered ones because they work so much better. And they are fine in pregnancy.

REHMDr. Fauci.

FAUCIYou know, that's great. I'm so glad Dr. Sheffield brought that up, because I get asked that a lot, and I'm not even an obstetrician, I'm a gynecologist, about pregnant women, who are concerned. There is -- pregnant women should not be concerned about using DEET containing repellants. You can use up to 30 percent DEET and it is safe in pregnant women. So pregnant women should not be concerned about not protecting themselves.

REHMAll right. We will follow this story, obviously, and hope that, at some point, Congress acts on that request for additional emergency funding. Dr. Anthony Fauci of the NIH. Maggie Fox of NBC News. Dr. Jeanne Sheffield of Johns Hopkins Medicine. Thank you all so much.

FAUCIGood to be with you.

FOXNice to be here.

SHEFFIELDThank you. Good to be with you.

REHMAnd thanks all for listening. I'm Diane Rehm.