Zika is an infection caused by a virus.
Research shows that getting Zika during pregnancy can cause birth defects in the developing fetus. In 2015, Zika virus infection was linked to microcephaly in newborn babies—a condition in which the brain and skull are smaller than normal. It also was linked to other problems with the adult nervous system.
Since then, public health agencies across the world, including NICHD, have tracked the outbreak and are conducting and funding research to understand how Zika infection affects health.