CAROL COSTELLO, CNN ANCHOR: And good morning. I'm Carol Costello. Thank you so much for joining. Three to four million Zika cases possible in the Americas: that frightening prediction is from the World Health Organization speaking about the Zika virus this morning. The organization, holding a virtual press conference in Geneva right. The level of alarm now extremely high -- Zika is linked to devastating birth defects and even death in babies. CNN's Rafael Romo is in Atlanta with more on this. Good morning.</s>RAFAEL ROMO, CNN SENIOR LATIN AMERICAN AFFAIRS EDITOR: Carol -- good morning. The head of the World Health Organization says the Zika virus is now spreading explosively -- those are his words -- around the Americas. Some of the most affected areas are in South America, especially countries like Brazil where 1.5 million infections were reported last year. Now let's talk about the mosquito that carries the virus. The Zika virus is transmitted by a very aggressive biter -- Carol, Aedis Aegypti mosquito. This mosquito feeds mostly during the day so bed nets won't help as much. But the main concern for health authorities is that Zika has been linked to a condition called microcephaly. This is a neurological condition that results in babies being born with abnormally small heads and sometimes even causes death. Brazil has reported 4,000 cases of microcephaly. So far there have been about 20 cases in the continental U.S. in states like Florida, Texas, and Illinois. And when it comes to microcephaly, only one case, and this happened in Hawaii. Now, there's an emergency meeting, as you were saying before. They're going to discuss what can we do about this disease? But again, it's rapidly spreading throughout the Americas, and it has already reached the United States -- Carol.</s>COSTELLO: Frightening. Rafael Romo -- thanks so much. Coming up in the NEWSROOM all eyes might be on the Republicans tonight, but Democrats are blanketing Iowa as we speak.
WHO: Three to Four Million Zika Cases Possible in Americas