LINDA WERTHEIMER, HOST:
There is now no doubt among scientists that the Zika virus causes microcephaly in babies born to infected mothers. These babies, born with very small heads, are generally diagnosed at birth. But new research from the federal Centers for Disease Control finds that some babies who appear to be normal at birth develop microcephaly within months due to the Zika virus. Dr. Denise Jamieson is incident manager for Zika response at the Centers for Disease Control and Prevention. Dr. Jamieson, welcome to the program.
DENISE JAMIESON: Happy to be here.
WERTHEIMER: Can you tell us - just give us a thumbnail about what the study found?
JAMIESON: This study describes 13 infants with congenital Zika virus infection. And these infants had a normal head size at birth, but their heads did not grow normally. The head circumference or head size is really just a measure of what's going on inside the brain. And microcephaly can be caused by either a disruption of development of the brain or destruction of brain tissue.
WERTHEIMER: I understand you've also discovered that babies born to infected mothers may be affected by the virus even if they don't develop microcephaly.
JAMIESON: I think all along the way, we've really focused too much on just microcephaly. Zika virus infection in babies is really more than just having a small head. These babies can be affected by a whole host of problems, including seizures, irritability, difficulty swallowing, problems with sight, problems with hearing. So there's really a whole host of problems that these babies can have.
WERTHEIMER: Are there still large populations of people who might have children exposed to the Zika virus? Do you - is it still out there, still dangerous?
JAMIESON: We anticipate that even though in many places in the world mosquito season is coming to an end, there'll be other seasons where there'll still be people who are susceptible to Zika virus infection. So we don't anticipate that this problem is going to go away really until there's an effective vaccine.
WERTHEIMER: Why do you think it's a significant study? Does it point the way towards something that should affect public policy?
JAMIESON: I think it focuses our attention on the fact that this is not all just about head circumference, the size of the head, that it's more complicated. And the most important message from this study is that these infants should have early brain imaging and really very careful, meticulous follow-up to ensure that they don't have problems with growth or problems with development later on.
WERTHEIMER: Well, it's interesting that in view of all of the things we don't yet know that the World Health Organization has downgraded the Zika virus and is no longer calling it a global health emergency. What does that mean?
JAMIESON: It is a bit perplexing. WHO's announcement, though, does not really change the fact that there's a critical need to continue our work here on Zika. Their announcement doesn't make Zika virus infection and the questions surrounding it any less of a public health emergency or any less tragic.
WERTHEIMER: Dr. Denise Jamieson. She is incident manager for Zika response at the Centers for Disease Control and Prevention. Thank you very much for talking to us.
JAMIESON: Thanks for your interest. Transcript provided by NPR, Copyright NPR.