The article by Edward B. Hayes discusses the emergence and spread of Zika virus (ZIKV) outside of its traditional geographic range, particularly in the Pacific Ocean and the Americas. ZIKV, a flavivirus related to yellow fever, dengue, West Nile, and Japanese encephalitis viruses, was first detected on Yap Island in 2007, marking the first time it was found outside of Africa and Asia. The virus causes a mild illness characterized by rash, arthralgia, and conjunctivitis. The article reviews the history, transmission dynamics, virology, and clinical manifestations of ZIKV, highlighting the potential for diagnostic confusion with dengue. It emphasizes the need for awareness and surveillance to prevent the spread of ZIKV, especially in the Pacific and the Americas, where the virus has the potential to cause significant public health impacts. The article also discusses the possibility of congenital infection and blood transfusion transmission, and suggests that further research is needed to define vector competence and identify other reservoir hosts.The article by Edward B. Hayes discusses the emergence and spread of Zika virus (ZIKV) outside of its traditional geographic range, particularly in the Pacific Ocean and the Americas. ZIKV, a flavivirus related to yellow fever, dengue, West Nile, and Japanese encephalitis viruses, was first detected on Yap Island in 2007, marking the first time it was found outside of Africa and Asia. The virus causes a mild illness characterized by rash, arthralgia, and conjunctivitis. The article reviews the history, transmission dynamics, virology, and clinical manifestations of ZIKV, highlighting the potential for diagnostic confusion with dengue. It emphasizes the need for awareness and surveillance to prevent the spread of ZIKV, especially in the Pacific and the Americas, where the virus has the potential to cause significant public health impacts. The article also discusses the possibility of congenital infection and blood transfusion transmission, and suggests that further research is needed to define vector competence and identify other reservoir hosts.