The Zika Virus Could Take a Huge Toll in the Americas

An African virus that historically rarely infected people is spreading in the Americas, apparently causing the babies of infected mothers to be born with deformed heads. The Zika virus is carried by mosquitoes and spreads when the insects bite. And though it appeared in the Americas just nine months ago in the Easter Islands off Chile, the World Health Organization said it will soon spread to almost all countries in the Americas, including to the United States.

In 2014, Brazilian health officials reported 147 cases of babies born with shrunken skulls: it was microcephaly, a congenital deformation of the skull that compresses the infants’ brains. In 2015, the number jumped to nearly 4,000 microcephaly cases reported in the country.