The Centers for Disease Control and Prevention may be changing its guidelines for travelers to make sure they're aware of the Zika virus, which is dangerous to pregnant women's unborn babies.

Doctors say the disease, carried by mosquitoes in tropical countries, has been linked to thousands of birth defects in Brazil during cases when it was not fatal. It most commonly leads to brain defects and severe developmental issues.

Haiti reported its first few cases of the virus on Friday.

A Texas woman who recently returned from South America became the first woman diagnosed in the United States with the virus.

Bridgeport Hospital's infectious disease expert, Dr. David Lobo, says there is no vaccine to block the Zika virus and no medicine to treat it.

"It's appropriate that we counsel women who perhaps don't really have to travel to areas, and who are in early stages of pregnancy, to be cautious about something like this," Lobo says.