Historically, symptomatic Zika virus infections were limited to sporadic cases or small clusters of patients. This pattern changed in 2007, when the first major outbreak of Zika virus infection occurred in Yap (Federated States of Micronesia), where ≈73% of the population were infected and symptomatic disease developed in ≈18% of infected persons (5). Since then, Zika virus infection has spread rapidly. Outbreaks have occurred in French Polynesia (6), Cook Islands (6), Easter Island (7), New Caledonia (8), and, most recently, the Americas (9), with sporadic exportations to Europe