FRIDAY, Feb. 12, 2016 (HealthDay News) -- At first glance, it seems like a small ray of hope in the ongoing Zika epidemic hitting Latin America.

Colombia's president said the other day that there were no signs of brain birth defects involving nearly 3,200 pregnant women in that country who were infected with the mosquito-borne virus.

This, of course, would be good news, given that unborn babies are assumed to bear the primary risk from Zika. The virus has been linked in Brazil to hundreds of cases of microcephaly, a birth defect in which the head and brain are unusually small.

But major public health institutions -- including the World Health Organization, the U.S. Centers for Disease Control and Prevention and the March of Dimes -- say it's too soon to tell whether the Colombia reports are accurate.

Colombian President Juan Manuel Santos stated last Saturday that there's no evidence Zika has caused any cases of microcephaly in his country, though 3,177 pregnant women have been diagnosed with the virus.

CDC researchers are fanning out across Central and South America to gather data on the crisis that has been centered in Brazil, and will independently check Santos' claim, said Dr. Edward McCabe, senior vice president and medical director of the March of Dimes.

"Hopefully, we will have information coming through CDC to confirm or not to confirm" Santos' remarks, McCabe said. "If that statement is true, it would be good news. But then we would be left with why are they seeing microcephaly in Brazil and not in other countries."

Since the Zika epidemic first surfaced in Brazil last spring, the virus has spread to 30 countries and territories in Latin America and the Caribbean. The World Health Organization now estimates there could be up to 4 million cases of Zika infection -- but not necessarily microcephaly birth defects -- in the Americas in the next year.

Santos' statement seems to run counter to a growing body of evidence linking Zika to microcephaly, although the connection has not been proven.