Zika without symptoms in returning travellers: What are the implications?

Against the background of the emergence and rapid spread of Zika virus (ZIKV) in the Americas, we report the case of an afebrile ZIKV infection in a traveller returning from Central America to highlight relevant clinical and diagnostic aspects. ZIKV should be considered in the differential diagnosis of patients with clinical symptoms suggestive of dengue or chikungunya fever. Given the frequent subfebril and afebrile manifestations of ZIKV infections, we propose abstaining from the term "Zika fever (ZF)" in favour of "Zika virus disease (ZVD)". Owing to its unspecific clinical presentation and cross-reactivity in serological assays, ZVD may easily be missed or misdiagnosed as dengue fever. Until conclusive data on the currently suspected link between ZIKV infection in pregnancy and foetal microcephaly become available, pregnant women and women who are trying to become pregnant should be advised against travelling to regions with ongoing ZIKV transmission. In addition, male travellers returning from regions with ongoing transmission should be informed of the potential risk of sexual transmission until conclusive data on the significance of this mode of transmission become available. Although probably low and seasonally restricted, there is a risk of ZIKV importation to Aedes mosquito-infested regions in temperate climates (including regions of North America and Europe) with consecutive autochthonous transmission.