Z IK A Virus What is Zika Virus? Zika virus ( ZIKV) is a member of the Flaviviridae virus family and the Flavivirus genus. In humans, it initially causes a mild illness known as Zika fever , Zika, or Zika disease, which since the 1950s has been known to occur within a narrow equatorial belt from Africa to Asia. In 2014, the virus spread eastward across the Pacific Ocean to French Polynesia , then to Easter Island and in 2015 to Central America, the Caribbean, and South America, where the Zika outbreak has reached pandemic levels. Illustration of Zika Virus. Zika virus is related to dengue , yellow fever , Japanese encephalitis , and West Nile viruses. The illness it causes is similar to a mild form of dengue fever , is treated by rest, and cannot yet be prevented by drugs or vaccines. There is a possible link between Zika fever and m