Zika virus (ZIKV) was first isolated in 1947 from a rhesus macaque held captive in the Zika forest in Uganda as a sentinel for yellow fever virus circulation. The first suggestion of its potential to cause sporadic human disease dates from the early sixties in the same country, but it was not until 2007 with the outbreak in Yap state (Micronesia) that ZIKV was recognized as a cause of outbreaks of mild febrile human disease. The general perception of ZIKV as a cause of benign infections transformed with the first indications of association with Guillain-Barré Syndrome (GBS) during the 2013/14 outbreak in French Polynesia. Following its rapid emergence across the Americas in 2015/16, the declaration of "clusters of microcephaly cases and other neurological disorders in areas affected by Zika virus" as a Public Health Emergency of International Concern by WHO in February 2016 further substantiated concerns about the potential severity of ZIKV infections. By 2017, it was established that although ZIKV generally causes mild or asymptomatic infections, it is a cause of GBS in adults, and congenital ZIKV infection may result in microcephaly and other congenital central nervous system (CNS) malformations, pre-term birth and miscarriage. Since the outbreak in Micronesia ZIKV has rapidly expanded its geographic distribution, and it is currently known to affect > 85 countries in Africa, Asia, the Pacific, the Americas and the Caribbean. An estimated 2 billion people live in areas of the world with environmental suitability for ZIKV circulation. Although most countries in the Americas and the Caribbean see a decline in the number of ZIKV cases, the situation in Africa remains obscure, while for Asia, increasing evidence from retro- and prospective studies points to a wide geographical circulation. The affected countries include many popular travel destinations for European citizens, and indeed many import cases of ZIKV infections in returning travellers have been reported and continue to be reported. Given the profile of ZIKV as a (re-)emerging pathogen and as aetiology of severe disease, clinicians and public health officials should remain vigilant about the risk of ZIKV infection in (returning) travellers and for ongoing local transmission. Pre-travel advice to prevent infection, especially in case of pregnancy or pregnancy wish, is necessary. To maintain this awareness to prevent, identify, manage and investigate ZIKV cases, this chapter reviews ZIKV epidemiology, pathogenesis, diagnostics and treatment.