'Nobody Is Immune': Bracing For Zika's First Summer In The U.S. : Shots - Health News Author Donald. G. McNeil Jr. predicts that 2016 will be the worst year for Zika transmission in the U.S. "After this year, a fair number of people will be immune, and ... immunity will grow," he says.
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'Nobody Is Immune': Bracing For Zika's First Summer In The U.S.

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'Nobody Is Immune': Bracing For Zika's First Summer In The U.S.

'Nobody Is Immune': Bracing For Zika's First Summer In The U.S.

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TERRY GROSS, HOST:

This is FRESH AIR. I'm Terry Gross. As people around the world prepare to travel to the Olympics in Brazil, where the Zika epidemic has hit hard, Zika is headed for its first summer in the U.S. If the virus is ever going to hit hard in the U.S., this summer will be its best opportunity. My guest, Donald G. McNeil Jr., explains why in his new book "Zika: The Emerging Epidemic."

We're going to talk about what we know about the virus, why it can affect a pregnant woman's fetus and how the virus can be spread sexually. And note to parents, the interview will include a brief part in which we talk clinically about sexual transmission. McNeil is The New York Times' main global health reporter and describes himself as covering every plague and pestilence that comes down the pike.

Donald McNeil, welcome to FRESH AIR. You write that if the virus is ever going to hit hard, this summer will be its best opportunity. Why?

DONALD MCNEIL JR: Because the entire population is naive. There's no herd immunity. Nobody in the United States has ever had Zika. Nobody in most of the Americas had had Zika before it landed probably in 2013. So after this year, a fair number of people will be immune. And each year, immunity will grow, assuming it isn't stopped by a vaccine or something.

And so this is the year where there will be more transmission than any other, presumably. I don't like predicting the future, but that's a good bet.

GROSS: When you say a naive population, what does naive mean in that kind of epidemiological context?

MCNEIL: Sorry, I mean, immunologically naive. That is to say, no one in the population has had the disease before, so nobody is immune to it. Nobody has antibodies to it. So the disease can blow through a population.

GROSS: So this is the kind of virus that you only get once?

MCNEIL: As far as we know, yes. And there's pretty good evidence that immunity is if not life-long, at least long-lasting.

GROSS: So what do we know about the inroads that mosquitoes carrying the Zika virus have made into the U.S.?

MCNEIL: They're all over Puerto Rico and the U.S. Virgin Islands and American Samoa. The mosquitoes that can transmit Zika are the Aedes aegypti mosquito. The yellow fever mosquito is strong or numerous all over the Florida and the Gulf Coast. And there have been previous small outbreaks of Dengue virus and Chikungunya virus in Key West, in Marion County, Fla., in Texas and in a few places like that.

The mosquitoes in very hot, wet summers can range as far as New York City and a touch North. It's not like they're very numerous up here. And it's not like they're here every month. And it's not even like they're here every summer. But they have been found up this far north. So the potential for transmission is there, although it's low outside of the tropical southeast.

GROSS: Are these mosquitoes that typically fly far distances?

MCNEIL: No, there is no mosquito that typically flies far distances. They're really inefficient fliers. And one of the best ways to keep mosquitoes off you if you're having a barbecue is just to have a fan blowing on everybody because most mosquitoes are lucky if they make it a mile in their lives.

I mean, once a while, they fly onto a jet and they make it from Africa to Paris, and that's why you have occasional cases of airport Malaria in Paris. But most of the time, mosquitoes only get a few blocks.

GROSS: So the World Health Organization has decided not to suggest canceling the Olympics in Brazil. On what grounds did they make that decision, since Brazil has a real problem on its hands with Zika?

MCNEIL: So the World Health Organization is not paying attention to the polluted bays and they're not paying attention to the crime rate or anything like that. They're paying attention only to Zika. And their decision - it's only a recommendation on their part. But what they're saying is they don't think Zika is so great that anybody ought to avoid going to the Olympics or that the Olympics ought to be canceled, unless you're a pregnant woman, in which case, pregnant women should avoid there, or unless you're somebody who's having sex with a pregnant woman or a woman who wants to get pregnant.

In which case, you have to be extremely careful. And the basis for this is that August is winter in Rio. And even though winter in Rio means temperatures of, you know, 70 to 80 degrees, it is the low mosquito season. If you look at the transmission of Dengue or Chikungunya in Rio, you see that it's roughly 5 percent of what it is at its height in January and February and March.

So they figure the risk is fairly low. And the Brazilians have convinced them that they're going to do everything they can to empty standing water and - you know, I think fogging is mostly a semi-useless exercise. But, you know, they're going to do what they can. So the recommendation is that it's OK to go unless you're pregnant or having sex with somebody pregnant.

GROSS: I should say that you mention Chikungunya. That's another mosquito-borne virus.

MCNEIL: Right, Dengue and Chikungunya, both carried by the Aedes aegypti mosquito.

GROSS: So is this controversial recommendation not to cancel the Olympics in Brazil - is that controversial within the global health community?

MCNEIL: People are split about it. I mean, the CDC isn't recommending canceling it either. Everybody agrees that pregnant women should stay away and women, you know, who might be pregnant. And everybody agrees that women of childbearing age need to be careful about who they have sex with and how they have sex with them while they're there, including the athletes.

But other than that, you know, Zika is a mild disease in 99.9 percent of cases. And so it's not as bad as Dengue or Chikungunya, for example. It's not nearly as bad as Malaria. It's one that if you're an otherwise healthy person, you shouldn't worry about. There's about 1 in 4,000 to 5,000 chance that somebody will get Guillain-Barre syndrome, which is terrifying but...

GROSS: That's a temporary paralysis.

MCNEIL: Exactly, it's temporary sort of creeping paralysis - usually temporary. I mean, some people get hit by it so hard and so fast that their breathing muscles - it's an ascending paralysis, meaning it starts in your hands and your feet and works its way towards your core. And in some cases, it goes so fast that people are not put on respirators and they can't breathe.

But that's very rare. Most people recover from Guillain-Barre. Some people have long-lasting pain or muscle numbness, but most people recover from it, although it takes weeks.

GROSS: We're learning that the Zika virus can be transmitted sexually. And I'm wondering if that's a game changer? I mean, is it possible that after the Olympics, people who are bitten by Zika-carrying mosquitoes will bring the virus back to their home country and spread it sexually?

MCNEIL: We don't have to wait for the Olympics for that to happen. It's happening right now. It happened in Texas in January. The virus can be transmitted sexually. That's a game changer, and scientists are just gobsmacked by this because there's never been a mosquito-borne virus that was transmitted sexually. You know, viruses mutate like crazy.

But one thing they don't normally change is how they're transmitted. So you don't expect a virus that might be transmitted by touching the wrong subway pole to become a sexually transmitted virus. And you don't expect a mosquito-borne virus to become something that can be transmitted through an act of unprotected sex.

But this one is. And it's not clear how often it happens, but it happens often enough so that it's the second most common form of transmission. And right now in New York City, despite all those subway posters saying watch out for mosquitoes, frankly, those subway posters ought to have, you know, good-looking guys on them because...

(LAUGHTER)

MCNEIL: Good-looking guys who have just come back from Puerto Rico or Brazil or the Virgin Islands or anyplace else are a bigger risk factor for Zika in New York City than mosquitoes are right now. There are no Aedes aegypti mosquitoes here. But there are good-looking guys who might, in remote chances, be carrying the virus.

GROSS: So what do we know now about how the virus is sexually transmitted and what's considered unsafe sex?

MCNEIL: We know it can be transmitted through virginal sex. We also know it can be transmitted through anal sex because there's been one case of a gay man transmitting it to his partner. There is some suspicion that it can be transmitted through oral sex because there is one case of a couple in France, and it looks like she was infected through oral sex.

So that may be a possibility, too. So basically, any sex involving mucous membranes is dangerous.

GROSS: So is the medical understanding as of now that the virus is transmitted through semen?

MCNEIL: Yes, which means it's only transmitted from men to women or from men to other men. There is no known instance of a woman transmitting the disease to a man or a woman. The assumption is that the virus gets into either the prostate or the testes and sets up an infection there. And it can persist for a long time.

We learned this with Ebola that once a virus breaks into the immunologically privileged parts of the body, which are separate from the rest of the body and have their own sort of fluids and - the eyes are immunologically privileged and the testes are immunologically privileged. Once a virus gets in there - it's hard for it to break in, but once it gets in, it's hard for the body to get rid of it because antibodies and white blood cells can't get in there to kill it.

So they have found viral RNA in men's sperm for as long as two months after the man's had an infection. So to be careful, the CDC is recommending that a man who's had Zika symptoms not have sex with anybody - unprotected sex with anybody for six months. And if the woman is pregnant, to be extra safe, they recommend that the couple not have unprotected sex for the entire length of the pregnancy.

GROSS: Are scientists confident that Zika is not carried through the saliva?

MCNEIL: Scientists know there is some Zika virus in saliva, but they don't think there are any cases of transmission. Similarly with breast milk, they know that Zika virus has been found in breast milk. They've never seen it transmitted from mother to child that way. And the advantages of breastfeeding are so great that they still encourage mothers to breastfeed, even if they've had Zika.

GROSS: All right, let's take a short break here, and then we'll talk more about Zika. My guest is Donald G. McNeil Jr. He covers science and health for The New York Times, writes about a lot of epidemics. And his new book is called "Zika: The Emerging Epidemic." We'll be back after this break. This is FRESH AIR.

GROSS: This is FRESH AIR. And if you're just joining us, my guest is Donald G. McNeil Jr. He's the author of the new book "Zika: The Emerging Epidemic." He covers science and health for The New York Times.

So we've talked about how unusual it is for a mosquito-borne virus to be sexually transmitted. It's also very unusual for a mosquito-borne virus to cross over into the placenta. Why is it so unusual for a mosquito-borne virus to do that?

MCNEIL: It's unusual because it just doesn't happen. I mean, that's kind of a tautology I realize, but we know it crosses the placenta and infects the baby. We don't know yet how it does. I mean, the placenta is a semi-permeable membrane, so most viruses don't cross it. But some do, and the consequences can be devastating.

Rubella, German measles, crosses the placenta and used to be the main cause of microcephaly and other birth defects and spontaneous abortions before the vaccine was invented. Cytomegalovirus does, herpes virus can, toxoplasmosis gondii can. There's a number of things that can cross the placenta and different mechanisms each time. But in Zika, it was kind of astonishing because it's related to viruses like dengue, like yellow fever, that don't cross the placenta and don't damage the fetus normally. And yet it does, and it does and in a sort of shockingly-high percentage of cases, although the exact percentage hasn't been worked out yet.

GROSS: I'm assuming that most of our listeners at this point know what microcephaly is, but I'm going to ask you to describe it anyways.

MCNEIL: Sure. Microcephaly - you've seen it in the pictures - it's babies born with tiny heads. You know, in the bad-old and politically incorrect days it was called pinheadism, and it means a tiny head and generally a very underdeveloped brain. And the babies have tiny smooth brains. And there are varying degrees of microcephaly, the most severe - the baby dies or the baby is born unable to swallow, has - may have repeated seizures and may die from those seizures, may never learn to walk, never learn to talk, never learn to control his or her bowels.

There's a whole range of ills to come out of it. And also, along with that comes - since it's a virus that attacks the growing brain, things like the nerves that connect the eyes to the brain or the ears to the brain are often damaged along the way. And so the baby will end up blind or deaf. But you may not know that when the baby's born. The eyes may look normal, but you suddenly realize they're not following objects or they're not hearing noises.

GROSS: So we know what the immediate range of effects is for microcephaly. What we don't know is what the long-term effects are if a baby's born with microcephaly as a result of the Zika virus. What are some of the concerns about the long-term effects.

MCNEIL: Well, some of the worries are even if a baby looks normal, there's a possibility that there may be long-term effects. This is scientists theorizing based on what they know about rubella virus and cytomegalovirus and some other viruses that can attack babies in utero that some of the children will grow up with learning disabilities, physical disabilities, you know, being unable to run or being able to coordinate themselves enough to play sports.

And there's a theory that it may lead - you know, the kids even have normal childhoods may develop schizophrenia or manic depression later at higher rates. This is based on observations from late manifestations of the rubella epidemic of the 1960s in this country, of some work by Finnish scientists on kids who were born after the 1957 flu epidemic. A higher percentage of them developed schizophrenia when they got older. And also, an observation that's been made for a long time that schizophrenia is higher in adults who were born in the late winter and early spring than it is in babies born in other months.

And the theory is that the mother's had, you know, flu infections that were strong, and they had a powerful cytokine storm immune response to it. And that may have affected the babies in ways that aren't obvious at birth but are - it manifests themselves later. Obviously, schizophrenia is affected by genetics because it runs in families and it's affected by trauma and drug abuse and a lot of other things. But the possibility is this might be one of the triggers.

GROSS: OK, so it's unusual for a mosquito-borne virus to be sexually transmitted as Zika is. It's unusual for a mosquito-borne virus to cross the line into the placenta as the Zika virus does. It is also unusual for a government to suggest that women wait to get pregnant as the Brazilian government has suggested. Why is that it so unusual?

MCNEIL: It's controversial. It's - I should correct this - it's not just - the Brazilian government hasn't made that suggestion officially. But the top doctor in charge of Brazilian government's response did make the suggestion early on. Some other governments have been very specific about it - the government of El Salvador, the governments of Colombia and Ecuador and Jamaica all suggested at one time or another that women not get pregnant. And the health secretary of Puerto Rico has suggested it, too. It's unusual because that's the end of a nation, you know, if the women stop having babies. But it's also controversial because, you know, China had its one-child policy which was - some public health advocates think was a good thing but which, you know, had some very bullying undemocratic enforcement methods to it.

And birth control in the Third World is a controversial issue at all times because it's often seen as white people in, you know, Washington or Geneva telling black people in Africa or people in Asia to stop having babies. And so even birth control advocates don't use the term birth control very often in Africa. They call it birth spacing to - and emphasize the advantage of spacing your children out, you know, so that the timing is of the mother's choice. So a lot of people in public health are reluctant to ever say don't have children, even though in this case a lot of infectious disease experts think it's probably very good advice to temporarily avoid having children if you can - if you can avoid not being pregnant in the high-transmission season in your country then it would be a good thing.

GROSS: What does temporarily mean? How long is this epidemic expected to last?

MCNEIL: Well, it depends on where you live. I mean, if you live near the equator, then there's probably going to be mosquito transmission all year round because you have basically rainy season and hot season, so they'll be a high mosquito transmission season in the hottest, wettest months. If you live in Florida, you'd only expect to have transmission in, you know, July and August, you know, the hottest, wettest months there because in Florida, January and February the mosquitoes get knocked way down by cold weather. So it varies basically with your latitude. But it is thought that the highest danger is during the first trimester, although by no means not all the danger over during the first trimester.

There are women in Brazil now who are rushing to get pregnant now because it's low-transmission season there. They might have waited for the first year, and it would be a good time to be - to get pregnant now so that they can get through their first trimester while the mosquitoes are not common. We're talking about - depending on where you are in Brazil - this is more like in the Rio area where they have a winter, even though it's not a cold, snowy, Jack Frost-type winter.

GROSS: What I'm wondering is - you know, it's - if you're supposed to not get pregnant for, like, a year or two, that's bad. But it's only a year or two. But if this is an epidemic that continues, I mean, it's not like yellow fever or malaria disappeared completely. So is this something that's probably going to be with us for, you know, years and years to come?

MCNEIL: Probably not, actually. I mean, years and years and No. It'll probably be two, three, four years until there's a vaccine. Most scientists who know vaccines say this is a disease that will be relatively easy to make a vaccine for because we have one for yellow fever, we have one for Japanese encephalitis. There's a new one for dengue. These are all related viruses. You could literally take the spines of those vaccine viruses and snip out the genes that code for the outside of the yellow fever virus and attach with DNA technology the genes for the outside of the Zika virus and make a pretty good vaccine.

Some of those vaccines have already been made, but now the testing process begins. And testing takes pretty close to two years at the minimum. How long the testing takes depends on how intense the epidemic is where you are doing your testing. You have to vaccinate enough people with the real thing and enough people with the placebo to see whether or not you get a significant difference between the vaccine and the placebo arms of the trial.

GROSS: But I thought that there were experts who were skeptical about a vaccine because of the possibility of getting Guillan-Barre from the vaccine.

MCNEIL: They're worried that that might show up, that if you've got a virus that causes Guillan-Barre, and we know that some vaccines have a tendency to cause Guillan-Barre. They're worried that essentially that the ethics boards that look at the vaccine experiments will say the chances of transmitting Guillan-Barre or sparking Guillan-Barre are too great. Let's not do it.

They're kind of outliers. They're kind of the most skeptical. I think most scientists who understand vaccines think look, even if there is some risk of Guillan-Barre, there's always some risk of Guillan-Barre. You and I are at risk of it now if we eat chicken, if we undercook it. We're at risk of it from any kind of flu or stomach flu or things like that. There's always some risk of Guillan-Barre. And if you're doing a great good saving a lot of babies from birth defects or death, then it becomes worth it to roll out the vaccine, even though no vaccine is perfect.

GROSS: My guest is Donald McNeil author of the new book "Zika: The Emerging Epidemic." We'll talk more after a break. And we'll listen back to my 1990 interview with Michael Herr, who died last Thursday. He wrote the 1977 book "Dispatches" about the war in Vietnam. He wrote the voiceover narration for "Apocalypse Now" and co-wrote Stanley Kubrick's Vietnam War film "Full Metal Jacket." I'm Terry Gross, and this is FRESH AIR.

(SOUNDBITE OF MUSIC)

GROSS: This is FRESH AIR. I'm Terry Gross, back with Donald McNeil, author of the new book "Zika: The Emerging Epidemic." He covers global health for The New York Times.

So we've been talking about the warnings to women in Brazil not to get pregnant, and I think, you know, women in parts of the United States.

GROSS: So we've been talking about the warnings to women in Brazil not to get pregnant. And I think, you know, women in parts of the United States are concerned about that, as well. What has the church's position been?

Has the church weighed in - the Roman Catholic Church - weighed in on contraception and Zika? Obviously, the church has always stood against contraception. But, you know, you're talking about - we're talking about microcephaly here.

MCNEIL: Mhmm. Well, the church isn't speaking with one voice entirely on this issue. Or I think it's working for the church, maybe. The church doesn't tell us whether or not it's working out its response or not.

But what has happened is - we have to draw a distinction between abortion and contraception here. I mean, no Catholic bishop and the pope is not, and never are, going to come out in favor of abortion. And their argument would be - it's better to suffer from raising a child with severe handicaps than it is to take an innocent life.

On the other hand, there's been a fair amount of disparate statements within the church about contraception in this case. The archbishop of Puerto Rico quickly spoke out against contraception when the health secretary of Puerto Rico suggested that women might want to delay pregnancy and said, you know, women should practice self-discipline. We have no problem with that.

But the church's position on artificial contraception is long been known. But the pope, in a conversation with reporters on a plane on the way back from another visit, was asked a question about Zika and said that under the doctrine of the lesser of two evils, it might be possible that contraception could be acceptable in a case like this because it would present - prevent - a great evil like deformity and suffering of a child.

And he drew the parallel to Pope Paul VI allowing the use of contraceptives by Belgian nuns in the Belgian Congo because some of them were being raped during the liberation struggle of the 1960s.

And that, you know, dropped like a rock into the Catholic pond - was kind of shocking. But it opened the door to the possibility that contraception might be OK in a - what would be considered an extreme case like this.

GROSS: Does Brazil have a lot of birth control available? Is there an equivalent of Planned Parenthood? Are OB/GYNs allowed to prescribe contraception?

MCNEIL: I don't know enough about Brazil itself to answer that question. I know that the statistics from the Guttmacher Institute suggest that for some countries in Latin America, Brazil included - but Brazil, Colombia, Venezuela, Ecuador, a few others - it's relatively easy.

It's up in the - you know, availability of birth control to married women - that's who was surveyed - is up in the 60 to 70 percent issue. Obviously, you know, teenagers often don't have access to birth control - the same way they don't in this country.

They don't know, you know, their only access to it is to go to the school nurse's office and look for a condom. And some schools do that and some schools don't. But married women often have a doctor.

They have been through - you know, they've been through a birth or two. And they can often seek out and find birth control - so yeah, in a lot of those countries.

And, you know, we know that birth control is available in these countries because fertility rates have fallen enormously in Latin America - the same way they fell in Italy and Ireland and the rest of the Catholic countries of Europe, you know, since the 1960s.

GROSS: What do we know about where and when Zika originated?

MCNEIL: We know it was discovered in 1947 in a monkey in the Zika Forest in Uganda, which is where it's got its name. And it was a British colonial virology laboratory that was set up. It sounds like a dark and mysterious place. And it means the overgrown forest. But it's actually on the road between Nairobi, the capital of Kenya, and the airport in Entebbe.

And scientists strung cages in trees - not in trees - but in towers they built. And the towers - the cages held monkeys. And the monkeys were hoisted up the treetop levels because there's different species of mosquito at different levels in a forest.

And the monkeys were taken down and their temperatures were taken. And they were tested. And one monkey got a fever. And they brought the monkey in the lab and drew some of its blood and then started on a whole series of tests that took - actually took months.

The first paper wasn't published until 1952, five years later. But they proved that there was a new virus out there. There's lots and lots of viruses that you've never heard of - that most people have never heard of - you know, Spondweni virus, Bunyamwera virus, Niambo (ph) virus, O'nyong'nyong virus.

And they're not - you know, we don't worry about them until all of a sudden, they come leaping out of, you know, one area or another, like Ebola, and become a problem. But that's - this is one that no one expected to be a problem because the disease has always been thought to be mild.

But now we discover it is mild unless you're a fetus, in which case it's deadly.

GROSS: So this way of trying to extract the Zika virus from a monkey - I mean, monkeys were put in cages, as you describe it - like the height of tall trees because the mosquitoes fly at different heights. Is that the kind of experiment you could do today? I mean, it sounds like you're using the monkeys as bait for mosquitoes.

MCNEIL: They were definitely using the monkeys as bait for mosquitoes. In those days, in the 1940s, that wasn't considered very ethically problematical.

Something else going on in the 1940s was that, you know, people killed tsetse flies by hiring fly boys, who were young African guys who would stand shirtless in the river brush, letting tsetse flies land on them so they could slap them. And they were paid a bounty per fly to bring in dead flies because the diseases - the flies carried diseases that could affect cattle.

But the flies also carried sleeping sickness, which is a horrible disease - kind of like rabies. And, you know, I mean, this isn't behavior that we engage in anymore. I mean, nowadays, you wouldn't need to go out and set monkeys up in trees and wait because now with PCR testing, you could - well, we do, actually, set out sentinel animals, including chickens and things like that in some places in the world.

You could capture live monkeys and draw their blood and test it later. There's lots and lots of testing. There's testing in bats going on right now. There's actually a viral genome project that's going on that's trying to find all the genomes of all the viruses that circulate in all the wild animals in the world in order to try to figure out what the next possible danger might be.

The thing is, you can discover hundreds or even thousands of viruses, but it's tough to know which one is going to become the problem. There was a very interesting paper written in 2009 saying that Zika virus was likely to invade the Americas.

But it was down on the sort of also-rans list that there were - Rift Valley fever and Japanese encephalitis were considered greater threats. And it's all very unpredictable.

GROSS: So will you be in Brazil for the Olympics, covering Zika?

MCNEIL: I'll be if my desk asks me to. We've got a whole team going to Brazil anyway. And one of them may peel off from covering the swimming or something to write about Zika. Or if they want me to go, I'll go.

GROSS: Are you concerned about going? I mean, this wouldn't be the first time you went to a place that had an epidemic that you were covering. How do you protect yourself?

MCNEIL: I'm not pregnant (laughter).

GROSS: No, you're not pregnant (laughter). You're not going to be pregnant.

MCNEIL: I'm not pregnant, and I'm not trying to get anybody pregnant.

GROSS: Right. So that's why you wouldn't be concerned.

MCNEIL: I've been worried about - I've been worried about other things much more than I'm worried about this. So no, I'm not worried about Zika for myself.

GROSS: I'm assuming you're not a hypochondriac, 'cause this would be a terrible beat if you were.

MCNEIL: (Laughter). Yes, I'm not a hypochondriac. I tend to sort of calm down hypochondriacs. Occasionally, when I'm covering diseases, I'll have - some colleague will come up and grab my arm and go, are we all going to die?

GROSS: (Laughter).

MCNEIL: And the answer is yeah (laughter) - but probably not of swine flu or (laughter) Ebola or whatever it is you're worried about this year, that I'm, you know, adding to the world panic about.

GROSS: Oh, I'm sure you have a lot of young colleagues and friends who are planning sometime in the near future or hoping sometime in the near future to get pregnant. What advice have you been given?

And I know you always tell people, I'm not a doctor. I'm a reporter. But you're a much more informed person than most of the rest of us are when it comes to these things.

MCNEIL: In the very beginning, before the CDC had issued a travel warning, I did have some colleagues come up to me and say, hey I'm about to take, you know, a babymoon in Puerto Rico or a holiday in the Dominican or someplace.

And I said, look, I don't think you should go. I'm not a doctor, you know, and the CDC hasn't issued travel advice yet, but I think they should. And, you know, what's going on there appears to me to be pretty scary.

So I wouldn't go. And some of them are very pleased that I said that because some were, you know, about to get pregnant or were in the early stages of pregnancy and it would have been a bad thing for them to go at that time.

It took the CDC a couple of weeks to get its act together and issue a travel warning. And so, yeah, I thought I performed a very tiny public service within the walls of The New York Times at that time.

GROSS: And are you especially cognizant of all the things you can catch when you're out and about? I know you go camping a lot.

MCNEIL: Well, the mosquitoes in California don't carry malaria or any other diseases. I don't drink out of streams the way I did when I was a kid because of giardia. Yeah (laughter).

My colleagues hate eating lunch with me at The New York Times because they'll be talking about, you know, what's going on in the mayor's office - something like that. And I'll say, oh, well there's this new disease in the - you know, diarrhea.

And they'll say, I'm eating here, you know. Stop. Don't ask Donald what he's working on. So it goes on at our lunch table. You know, I'm aware. But I've also had more shots than most people, too. So I try not to panic about things.

GROSS: Right. OK, well, Donald McNeil, thank you so much for talking with us.

MCNEIL: Thank you very much for inviting me.

GROSS: Donald G. McNeil is the author of the new book "Zika: The Emerging Epidemic." He covers global health issues for The New York Times. After we take a short break, we'll listen back to my 1990 interview with Michael Herr, who died Thursday. He wrote the Vietnam War book "Dispatches." And the voiceover narration for Apocalypse Now - this is FRESH AIR.

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