Illustration showing the structure of the immature Zika virus capsid (protein coat). Zika virus is an RNA (ribonucleic acid) virus from the Flaviviridae family. It is transmitted to humans by Aedes sp. mosquitoes. The virus infects skin cells and spreads to the bloodstream. It causes zika fever, a mild disease with symptoms including rash and joint pain. In pregnant women it may cause foetal microcephaly (small head) leading to miscarriage or death soon after birth, or developmental disorders.