Alarm over thousands of birth defects blamed on mosquito-borne virus Zika spread Friday, as the United States expanded a travel warning for pregnant women over the illness. With the sting of a mosquito bite and a fever, many pregnant women may not know that they caught the Zika virus — until it strikes their unborn child. Now authorities in some Latin American countries are warning women to avoid getting pregnant for fear of the virus.

Babies across the region, and at least one in the United States, have been born with abnormally smaller heads — a condition doctors call microcephaly, which can cause brain damage. The scare has struck hardest in Brazil, which hosts the summer Olympic Games in August. It is one of 22 territories that the United States has warned pregnant women not to visit because of the Zika risk. FULL REPORT