IRA FLATOW: This is Science Friday. I’m Ira Flatow. A bit later in the hour, we’ll be wrapping up the Sci Fri Book Club with a discussion of Oryx And Crake by Margaret Atwood. Have a burning thought about that gloomy biotech dystopia? The pigoons? The re-engineered human beings or anything else? Give us a call. Our number 844-724-8255 844-SCITALK or tweet us @SCIFRI.

But first, the Olympics may be over, but the threat of Zika still looms large. In fact, while the CDC is keeping its collective eye on two clusters of Zika infections in Florida, government officials expect the virus will inevitably spread. In the meantime, a new study suggests that Zika may have a long-term impact on healthy adult mouse brains, which could portend bad news for humans. Here to give us an update on those things and where things stand with Zika is Dr. Anthony Fauci, director of the National Institutes of Allergy and Infectious Diseases and recipient of the Presidential Medal of Freedom. Dr. Fauci, welcome back to Science Friday.

ANTHONY FAUCI: Good to be with you, Ira.

IRA FLATOW: Let’s start with the news out today that the FDA is recommending that all donated blood be tested for Zika?

ANTHONY FAUCI: Yes. That is correct, and I think that’s prudent and a good idea, Ira, for a number of reasons. There are at least 2,500 individuals in this country with travel-related Zika. Namely they got Zika in another country, very likely South America, Central America or the Caribbean, and come to the United States, or our Americans who go there, visit, and come back. So those are the minimum amount. There are probably many more than that, because a lot of people who get about 80% of people who get infected with Zika don’t know they’re infected.

So there is the possibility that there will be an inadvertent entry into the blood supply. A unit of blood donated innocently by someone who is infected with Zika and had no idea that they were infected. So screening of the blood, I think, is the prudent thing to do, and it’s something that will make the blood supply safe and prevent the dissemination of the Zika by yet again, another mechanism, the blood supply. We know it can be transmitted by mosquitoes. We know it can be transmitted sexually. You want to protect the blood supply to the extent you can, so I think this was a good idea on the part of the FDA.

IRA FLATOW: It’s funny people are going to finally be listening more about it, now that it’s gotten a lot of coverage, first, with the Olympics and now in Florida. And people are paying, as I said, more attention. They’re going to be sitting on an airplane wondering if I’m going to Florida or coming back from Florida and somebody sneezes on me, is that a transmission method?

ANTHONY FAUCI: No, no. Absolutely not. I’m glad you brought that up. And it is always the case when you have communicable diseases, when you have diseases that are spread, infections, there’s always a concern about what is the mechanism of spread. It is spread predominantly and overwhelmingly by mosquito bites, by a mosquito biting an infected person and then biting someone who’s not infected. We also know now that it has been documented cases of sexual transmission, mostly from men to women, but also a case or so that goes from a woman to a man. And we do know from experience in other countries that when Zika gets into the blood supply, you can transmit it by blood transfusions. And that’s really the reason for the recent action by the FDA.

IRA FLATOW: I want to ask you about this Zika mouse study, about the problems with the brains of the mice. Can you explain what the researchers found there?

ANTHONY FAUCI: Yeah, what they found, Ira– and I want to make sure people don’t get the wrong impression from this and make more out of it than is justified at this point. It’s a study that you should take seriously, but you have to remember, it’s a mouse study in which the investigators infected adult mice with Zika to see if there was any effect on the adult brain. We know that the virus clearly has a very deleterious effect on the developing brain, hence the congenital abnormality that we’re seeing in people who get infected with Zika during their pregnancy. Pregnant women, particularly in the first trimester.

But this was a different question. This is the question is what happens to the adult brain. And what the investigators showed is that when you would infect an adult mouse, that you can get stem cells in the brain that can get infected. So that is something you want to pay attention to. But what was not shown was whether or not the animals it had any effect on their function at all, or what the physiological or clinical relevance that might be.

So people will immediately ask the question, well, if an adult gets infected with Zika, you’re going to have an effect on their brain? If you look at the tens of thousands of people who’ve been infected with Zika, there’s no indication– although it wasn’t formally followed in a study– there was no indication that infection of an adult has any impact negatively on the brain of that adult. Having said that, you want to take animal studies seriously and make sure you keep an eye out for the possibility that you might be missing some subtle effects. But thus far, it does not look like there are any in the adult human.

IRA FLATOW: Let’s talk about what’s going on with the flooding in Louisiana. Is that making it more likely that Zika will show up there because of all that water in the breeding grounds?

ANTHONY FAUCI: Well, it’s a complicated story when you’re talking about flooding, Ira. That sometimes can be confusing. Floods in general, when you just take floods as a flood, generally wipe out mosquito propagation places and eggs and larvae and things. But following flooding, when the flood resides, in some situations– and there isn’t necessarily a lot of direct proof of that– you could have standing water that could be a problem. But even as important as that is that in areas where there are a flood around the areas that don’t necessarily flood, there’s a lot of rain. And when you have a lot of rain, that’s when you have a lot of standing water and that’s where you can get the problem. So anything that contributes to standing water could potentially– and I underline potentially– have a negative effect on what you’re trying to do in getting rid of the mosquitoes.

IRA FLATOW: Would you be surprised if Zika does not spread further than Florida where it is now?

ANTHONY FAUCI: No, I would not be surprised if it does not spread. Although you have to be prepared for any possibility, I do not think that we’re going to see a disseminated type of a Zika outbreak, similar to what we’ve seen in Brazil in January and February and what we are currently seeing in Puerto Rico. But it is not unlikely that we will see what we are already seeing in Florida, namely, individual cases and some cases of clusters and ongoing transmission like we’re seeing in the Wynwood section and in the South Beach section of Miami Beach.

It is possible that this would just shut down and we won’t see anymore. I think that’s unlikely, Ira. I think we’re going to see a few more cases. Hopefully, the aggressive mosquito control activities of the Florida authorities, together with the CDC, are going to prevent it from becoming significantly more than it is.

So if we see no other cases, I wouldn’t be surprised. I don’t think that’s the case. I think we’re going to see a few more, and if we see a few more, I’m not going to be that surprised by it, because there are so many people who have travel-related cases. There are about 500 of them in Florida, so the opportunity for mosquitoes to bite an infected person and pass it on to someone else there. Hopefully, mosquito control methods will prevent that from becoming widespread.

IRA FLATOW: Well, isn’t it not true that most people or many people who have the virus don’t know they have the virus?

ANTHONY FAUCI: Exactly. And that’s the reason why the numbers, when you talk about infected people, it’s always an underestimate. 80% of people who are infected with don’t know they’re infected. They have no symptoms. 20% of them have a relatively mild illness. Fever, rash, aches and pains, and some red eye or conjunctivitis. So there’s a proportion of people the majority don’t know they’re infected.

IRA FLATOW: And let’s talk about the state of coming up with the Zika virus vaccine. Where are we in that?

ANTHONY FAUCI: Well, we’ve been accelerating our pace of a vaccine development. We started on August the 2nd. The phase one trial of one of about four or five candidates that are lined up in succession to go into trial. Phase one means you’re just asking is it safe and does it induce the kind of response that you would predict would be protective?

We started it on August 2nd. There’s going to be 80 people in the trial. It’s going to take place in Bethesda, Maryland outside of Washington DC, in Emory in Atlanta, and in the University of Maryland at Baltimore. We should finish that by the end of 2016 November or December.

And then if we get the resources, we’re going to transition quickly into a phase 2 trial that’s going to look at maybe between 2,400 and 5,000 people in areas where there is active transmission to see if it works. So we’re really right on a pathway of multiple candidates to determine if we can get a vaccine. That’s on an accelerated pace.

IRA FLATOW: You put your finger on a $64– I know it’s going to be a lot more expensive than that– question. And last time you were on a few weeks ago, when we talked about this, you said that there was enough congressional money, enough money in the budget to pay for the phase one trial, but there was not enough for the phase two part. Is that still the case?

ANTHONY FAUCI: That’s still the case. So what happened, Ira, is that to get the site prepared for the phase two Secretary Burwell had to use her transfer authority to move money out of other components of NIH to give to the vaccine effort from my institute, which was hurtful to cancer research, to heart, lung, and blood research, to diabetes research. That money is going to get me through September, but if we don’t get an appropriations in fiscal 2017, I will not be able to proceed with the phase two trial in January and February of 2017. That would really be a shame, because that would interrupt the smooth flow of that pathway to a vaccine.

IRA FLATOW: So you would need a lame duck version of Congress to come back and appropriate the money?

ANTHONY FAUCI: Well, yeah. That’s what we were hoping for, Ira. We really hope that Congress does appropriate the money to allow us not only NIH, but also CDC. CDC is playing a major role in things like mosquito control, in certain areas, partnering with the state and local health authorities, so they’re in the same boat as we are that at the end of this fiscal year, at the end of September, we’re essentially running out of money.

IRA FLATOW: So it’s you really think that Congress will do this? Come back and give you the money. This is such a political football now in the season that we’re in.

ANTHONY FAUCI: Yeah. I hope so, Ira. I really do. I mean, I’m just hoping that they do that, because they’ve risen to the occasion of the past in emergencies. I hope they do that here so that we can get going and continue to do what we’re doing.

IRA FLATOW: Well, the unfortunate good news I guess, about that is it’s getting the attention it’s getting in Florida where people are noticing it.

ANTHONY FAUCI: Well, certainly they’re noticing it in Florida when you have two neighborhoods that where you have a guideline that pregnant women should not go to those neighborhoods. That’s an eye-opener for people.

IRA FLATOW: Dr. Fauci, as always, thank you for taking time out of your busy day to come talk with us.

ANTHONY FAUCI: It’s good to be with you, Ira.

IRA FLATOW: And Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases at the NIH.

Copyright © 2016 Science Friday Initiative. All rights reserved. Science Friday transcripts are produced on a tight deadline by 3Play Media. Fidelity to the original aired/published audio or video file might vary, and text might be updated or amended in the future. For the authoritative record of ScienceFriday’s programming, please visit the original aired/published recording. For terms of use and more information, visit our policies pages at http://www.sciencefriday.com/about/policies