Association and birth prevalence of microcephaly attributable to Zika virus infection among infants in Paraíba, Brazil, in 2015-16: a case-control study.

Background: In 2015, the number of infants born with microcephaly increased in Paraíba, Brazil, after a suspected Zika virus outbreak. We did a retrospective case-control investigation to assess the association of microcephaly and Zika virus.

Methods: We enrolled cases reported to the national database for microcephaly and born between Aug 1, 2015, and Feb 1, 2016, on the basis of their birth head circumference and total body length.