The mosquito-borne Zika virus may be responsible for an increase in birth defects in U.S. states and territories, even in women who had no lab evidence of Zika exposure during pregnancy, U.S. health officials said Thursday.
Areas in which the mosquito-borne virus has been circulating, including Puerto Rico, southern Florida and parts of southern Texas, saw a 21 percent rise in birth defects strongly linked with Zika in the last half of 2016 compared with the first half of that year, the Centers for Disease Control and Prevention said in its weekly report on death and disease.
Researchers said it was not clear if the increase was due to the local transmission of Zika alone or if there were other contributing factors.