Low seroprevalence of Zika virus infection among adults in Southern Taiwan

Yu-Wen Chien,Wen-Chien Ko,Nai-Ying Ko,Guey Chuen Perng,Tzu-Chuan Ho,Pei-Wen Huang

doi:10.1186/s12879-019-4491-4

Abstract

BackgroundWe recently conducted a serosurvey of newly arrived workers in Taiwan from four Southeast Asian countries which revealed that 1% of the migrant workers had laboratory-confirmed recent Zika virus (ZIKV) infection. Taiwan, where Aedes mosquitoes are prevalent, has a close relationship with Southeast Asian countries. Up to now, 21 imported cases of ZIKV infection have been reported in Taiwan, but there has been no confirmed indigenous case. The aim of this serosurvey was to assess whether there was unrecognized ZIKV infections in Taiwan.MethodsA total of 212 serum samples collected in a cross-sectional seroepidemiologic study conducted during the end of the 2015 dengue epidemic in Tainan, Taiwan, were analyzed. Anti-ZIKV IgM and IgG were tested using commercial enzyme-linked immunosorbent assays (ELISAs). Plaque reduction neutralization tests (PRNTs) for ZIKV and four dengue virus (DENV) serotypes were performed for samples with positive anti-ZIKV antibodies. A confirmed case of ZIKV infection was defined by ZIKV PRNT90 titer ratio ≥ 4 compared to four DENV serotypes.ResultsThe mean age of the 212 participants was 54.0 years (standard deviation 13.7 years), and female was predominant (67.0%). Anti-ZIKV IgM and IgG were detected in 0 (0%) and 9 (4.2%) of the 212 participants, respectively. For the 9 samples with anti-ZIKV IgG, only 1 sample had 4 times higher ZIKV PRNT90 titers compared to PRNT90 titers against four dengue virus serotypes; this individual denied having traveled abroad.ConclusionsThe results suggest that undetected indigenous ZIKV transmission might have occurred in Taiwan. The findings also suggest that the threat of epidemic transmission of ZIKV in Taiwan does exist due to extremely low-level of herd immunity. Our study also indicates that serological tests for ZIKV-specific IgG remain a big challenge due to cross-reactivity, even in dengue non-endemic countries.

Highlights

We recently conducted a serosurvey of newly arrived workers in Taiwan from four Southeast Asian countries which revealed that 1% of the migrant workers had laboratory-confirmed recent Zika virus (ZIKV) infection
The first isolation of ZIKV was from Aedes aegypti in Malaysia in 1966 [6], and the first confirmed human case of ZIKV infection was documented in Indonesia in 1977
This study utilized a subgroup of blood samples collected in a cross-sectional seroepidemiologic study conducted during the end of the 2015 dengue epidemic caused by dengue virus (DENV) serotype 2 (DENV2) in Tainan City, Taiwan [13]

Summary

Introduction

We recently conducted a serosurvey of newly arrived workers in Taiwan from four Southeast Asian countries which revealed that 1% of the migrant workers had laboratory-confirmed recent Zika virus (ZIKV) infection. We recently conducted a serosurvey of 600 newly arrived workers from four Southeast Asian countries including Indonesia, Philippines, Thailand, and Vietnam in Taiwan using commercial enzyme-linked immunosorbent assays (ELISAs) and plaque reduction neutralization tests (PRNTs) for further confirmation [8]; the results showed that 6 (1%) of the migrant workers had laboratory-confirmed recent ZIKV infection defined using the World Health Organization criteria [8], suggesting the incidence of ZIKV infection in Southeast Asian countries may be severely underestimated and the risk of transmitting ZIKV from migrant workers and travelers from Southeast Asia cannot be neglected

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