dr. seema yasmin. doctor, thank you for joining us and speaking with us about this today.f a sudden it seems like this zika virus started to spread quickly. the cdc says now it causes microcephaly in newborns, which for this type of virus is actually very new. explain this. >> yes, errol we have to explain the link between this birth defect and the microcephaly has not been proven by the studies. so what the brazilian studies are doing, they say since the massive outbreak they're seeing since last may and a very big number of babies born with smaller heads and brains. so we need to wait for proof on what is suspected. but it is concerning to the health officials in the u.s. and other nations to say that women should not travel to a list of countries, and the list keeps growing, whether there is a potential harm that it could do to the fetus. >> and why is this virus spreading quickly now? >> probably a few reasons, we are doing surveillance now, but it could have been causing sickness before and we were not seeing it. another reason it could be seen in such large numbers i