From July to September 2015, several months after the introduction of Zika virus into northeastern Brazil, obstetricians noticed an increased number of fetuses with congenital malformations during ultrasound screening. By October, the number of newborns with microcephaly had increased significantly in this area. Microcephaly has now risen in other regions along with the spread of Zika virus. To date, more than 4000 cases have been reported.
Ann Intern Med. Published online 24 February 2016 doi:10.7326/M16-0332