RALEIGH (AP) — The state epidemiologist says North Carolina public health officials are following the cases of a handful of pregnant women who have either tested positive for the Zika virus or gotten an indeterminate result.

Dr. Megan Davies told the State Emergency Response Commission on Friday that the women have agreed to be on the registry managed by the Centers for Disease Control and Prevention. Officials can then follow their cases to learn more about Zika.

Zika is usually spread through mosquitoes, although sexual transmission also is possible.

Davies says about 75 percent of people with Zika have no symptoms, while others report a fever, rash or muscle aches. But infection during pregnancy can lead to severe brain-related birth defects.

Nineteen cases have been reported in North Carolina, all traveled-related.