This is a rush transcript from "Your World," June 3, 2016. This copy may not be in its final form and may be updated.

STUART VARNEY, GUEST HOST: Fears of Zika being transmitted by kissing? That what some scientists are saying.

To Dr. Tom Frieden, the director of the Centers for Disease Control.

Can we start there, Doctor? Can you transmit the Zika virus by kissing?

DR. THOMAS FRIEDEN, DIRECTOR, CENTERS FOR DISEASE CONTROL AND PREVENTION: This is a virus transmitted by mosquitoes. That's what is spreading it in places of the world where Zika is spreading.

If someone has Zika, we have found that sexual transmission is possible, but it's rare. This bottom line with Zika is, if you're pregnant, don't go to a place where Zika is spreading. If you're a male and you have been a place, someplace where Zika is spreading, and your partner is pregnant, use a condom.

This is unprecedented. It's the first time we had a virus spread by a mosquito that can cause a birth defect.

VARNEY: Can we just go through some of the risk areas? Because our viewers want to know, what is the risk that we face.

A woman who is bitten by a mosquito that has the virus, is it always transmitted to the child?

FRIEDEN: We don't know exactly how often, but there are women who have been infected with Zika, but given birth to apparently normal babies.

It may be months or years before we know for sure whether that baby is entirely normal. But the risk appears to be especially early in pregnancy, and, again, these mosquitoes are only spreading Zika in parts of the world where Zika is spreading.

That doesn't include anywhere in the mainland of the United States as of today. But we're concerned, because summer is heating up and so is Zika.

VARNEY: What's the best form of control here? Is it -- in the short term? I'm sure it's a long time before we get some kind of vaccine. In the short term, is the best method of dealing with this just really tight mosquito control?

FRIEDEN: Well, the best thing is, if you're in this country and you're pregnant, don't travel to a place with Zika.

And if -- for men, if you have been there and your partner is pregnant, use a condom. But for control in the areas where Zika is spreading, such as Puerto Rico, there's no one answer.

We protect pregnant women. We reduce the mosquito populations. And that's not easy. This is the cockroach of mosquitoes. It's hard to kill, it lives indoors. There's no easy answer to getting rid of it. That's why it's so important we get more resources, so that we can figure out how to control this mosquito, how to diagnose the infection better, and also what more can be done to track, monitor and support women whose children may have been affected.

VARNEY: Is this a question of money? You need more?

FRIEDEN: Money is important.

We don't have a way to redirect in an emergency the kind of money that we need for the short- and long-term projects that have to happen today. That's why I remain hopeful that Congress will act. Congress did the right thing with Ebola. That allowed us to stop Ebola overseas and prevent it from coming here. I'm hopeful they will do the right thing with Zika as well, so that we can protect American women and their pregnancy.

VARNEY: Are you concerned about American athletes traveling to Brazil for the Olympics? Are they properly protected?

FRIEDEN: Our recommendation for travel is regardless of why you are traveling. If you're pregnant, we advise you not to go. If you're not pregnant, there are steps you can do to reduce your risk of infection.

VARNEY: If you're a man, and you're bitten by a mosquito with the Zika virus, is that transmitted to your female partner and then on to the child? In other words, can the man pass it along, so to speak?

FRIEDEN: That is possible. We're still figuring out exactly when and for how long, but that's why we advise men who have been in a Zika-affected area, if you're back and your partner is pregnant, please use a condom.

VARNEY: How many women pregnant in America at this moment have the Zika virus, to your knowledge?

FRIEDEN: Three hundred and forty-one American women living here, got pregnant here, went on a trip, the vast majority of them before we knew this was happening, have come back and have laboratory evidence that they probably have Zika infection.

We're monitoring, supporting, helping, but we're obviously concerned, because some number of those will give birth to affected infants.

VARNEY: Sir, that's a very large number of people. And has the travel warning gotten out there, to your satisfaction?

FRIEDEN: Well, what we have seen is, it looks like the number who have been affected have come down quite a bit since our travel warning first went out January 15, which was literally within days of seeing the virus in the brains of infants who tragically had died from this.

That's why we're reiterating the advice that, if you're pregnant, don't go to somewhere where Zika is spreading. And it's so important that we figure out more how it's happening, how to stop it, how to diagnose it.

This is a relatively new infection. Our scientists, our doctors are working around the clock to come up with better tests, better ways to control the mosquito. But we do need the support, so we can do that to protect American women.

VARNEY: Got it.

Dr. Thomas Frieden, director of the Centers for Disease Control, thank you, sir. We appreciate you being with us. Thank you.

FRIEDEN: Thank you.

VARNEY: All right.

END

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