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CDC Expects Larger Numbers Of Zika Virus Cases To Be Reported


Controlling the Zika virus requires understanding it. That's part of the job of our next guest. Beth Bell works for the Centers for Disease Control, which has been observing the virus now linked to severe birth defects in Latin America. She is confident that conditions in the United States will not allow a major outbreak of this mainly mosquito-borne virus. But it is coming in some form, and she says, frankly, there's a lot more she would like to know.

BETH BELL: This current situation is certainly very new - for example, this apparent ability of the Zika virus to cause infection in a fetus when a pregnant woman gets infected. And there very likely will be many more things that we learn as we go.

INSKEEP: How well do you understand the way the virus is spread?

BELL: I think that we feel pretty confident that the major mode of transmission is from an infected mosquito. But we certainly have already identified this mode of transmission from an infected mother to a fetus. There's a case report in the literature that suggests sexual transmission might be possible. There are other potential modes of transmission from what we know from other viruses. So there's a lot that the Food and Drug Administration will be doing about the blood supply to prevent transmission from blood transfusions. And again, I think in this developing situation what we try to do is focus on the major mode of transmission while at the same time we're looking to evaluate whether the virus is behaving in a way other than what we would expect so that people know what they can do to protect themselves from what we know are the major modes of transmission.

INSKEEP: To what extent is it necessary to test pregnant women as they return to the United States or arrive in the United States from affected countries?

BELL: So we do have some interim recommendations that pregnant women who have symptoms consistent with Zika be tested. I'm sure that you know and many listeners know that most people with Zika infection don't have symptoms.


BELL: And so I think that there's, you know, a logical question of why are we only recommending testing pregnant women who have symptoms. We recognize, actually, that we really need to improve the lab tests that we have available right now. We want to be sure that when we're testing that we're confident that a positive is really a positive, and a negative really is a negative.

INSKEEP: You're saying that the testing is just not good enough that it would be worth the exposure and the difficulty of testing everyone. You'd end up with a lot of false positives and panic that wouldn't be very productive.

BELL: I'm saying that the tools that we have right now are just not going to really help in that situation.

INSKEEP: Let's be as realistic as we can here. You have indicated for many reasons that you don't think that conditions are good for widespread outbreak within the United States. But realistically, should we expect cases to be reported in the United States in larger numbers than they have been?

BELL: Yes, we will see cases reported in the United States in larger numbers. First of all, we will see more cases reported among returning travelers to the United States. And you might recall that we had another mosquito-borne virus within - called chikungunya which spread through the Americas over the last couple of years. And we had several thousand cases in returning travelers. But again, although we never say never, we think that it's quite unlikely that we'll see widespread transmission in the United States.

INSKEEP: Beth Bell of the Centers for Disease Control, thanks very much.

BELL: Thank you so much. It's been a pleasure talking with you. Transcript provided by NPR, Copyright NPR.