Zika virus infection in travellers returning to the United Kingdom during the period of the outbreak in the Americas (2016-17): A retrospective analysis.

Abstract

In 2016, Zika virus (ZIKV) spread rapidly throughout the Americas and Caribbean in an explosive outbreak. In the UK, testing for ZIKV infection is performed at Public Health England's Rare and Imported Pathogens Laboratory. Here we present the UK's experience of imported ZIKV during the epidemic. A retrospective review was performed on the laboratory computer system searching by orders for ZIKV PCR and/or ELISA serology tests between 1st January 2016 and 31st December 2017. Each individual request form and result was reviewed. Of 6333 symptomatic patients tested for ZIKV, 374 (6%) had molecular or serological evidence consistent with recent infection; most of these had travelled to the Caribbean in 2016. On follow-up of PCR-confirmed cases, ZIKV IgM disappeared within 6 weeks and often didn't appear in patients with previous dengue infection. Rash was the commonest symptom in PCR-confirmed infection (93%). There were only single cases of presumed sexual transmission and of in-utero transmission. The rise and fall in numbers of imported ZIKV cases largely reflected the temporal course of the outbreak in the Caribbean. ZIKV serology is difficult to interpret but the absence of antibodies to ZIKV 14 days after symptom onset makes infection very unlikely.