Zika Virus (ZIKV) was first recognized in 1947, in Uganda, when fever developed in a rhesus monkey that had been placed in a cage on a tree platform in the Zika forest. This monkey was a sentinel animal in the Rockefeller Foundation’s program for research on Yellow Fever. The serum of this monkey, when inoculated intracerebrally in mice, induced a cerebral infection. A filterable transmissible agent was isolated from the brain of the mouse, which was later named “Zika Virus.”
A year later, the virus was isolated from the Aedes africanus mosquitoes, trapped in the same forest, thereby establishing a transmission cycle involving the mosquitoes and monkeys.
From 1951 through 1981, serological evidence of human ZIKV infection was reported in Africa and Asia, including Malaysia, Philippines, Thailand, Vietnam and Indonesia.
The first ZIKV outbreak occurred in Yap Island in Micronesia, in 2007, outside Africa and Asia. This was followed by a second large outbreak in French Polynesia in 2013-2014. Subsequently it spread to the Pacific and continued to circulate through 2015.
ZIKV was rare in the Western Hemisphere, until May 2015, when the Public Health Authorities of Brazil confirmed an outbreak in Northeast Brazil. The virus has since spread to 22 countries and territories of the Americas; forcing the Pan American Health Organization to issue an alert, declaring Zika virus infection as a public health emergency of international concern.