The state of Florida announced Wednesday that three pregnant women who had traveled outside the United States tested positive for Zika virus.

To protect their privacy, the state is not revealing the names or locations of the women.

Zika has been associated with the birth defect microcephaly and Guillain-Barre, a rare syndrome where the immune system attacks nerves.

Microcephaly is a neurological disorder that results in babies born with abnormally small heads, causing severe developmental issues and sometimes death.

Since October, Brazil has seen 508 confirmed cases of microcephaly in newborns. At least 17 of those cases have a confirmed link to the Zika virus. There were only 146 cases in 2014. So far, 27 babies have died from the condition, with at least five linked to Zika. An additional 70 deaths are under investigation, and authorities are investigating 3,935 suspected cases.

The World Health Organization chief said Wednesday that the evidence coming out of Brazil points to Zika as a possible cause of microcephaly.