Congenital Zika Virus Infection in a Birth Cohort in Vietnam, 2017–2018

Abstract

To detect congenital ZIKV infection (CZI) in a birth cohort and among high-risk neonates in Vietnam, we collected umbilical cord blood plasma samples of newly delivered babies and peripheral plasma samples of high-risk neonates in Nha Trang, central Vietnam, between July 2017 and September 2018. Samples were subjected to serological and molecular tests. Of the 2013 newly delivered babies, 21 (1%) were positive for Zika virus (ZIKV) IgM and 1,599 (79%) for Flavivirus IgG. Among the 21 ZIKV IgM-positives, 11 were confirmed to have CZI because their plasma samples had anti-ZIKV neutralization titers ³ 4 times higher than those against dengue virus (DENV)-1 to 4 and Japanese encephalitis virus (JEV) and were tested for the ZIKV RNA positive by real-time reverse transcription-PCR. Therefore, the incidence of CZI in our birth cohort was approximately 0.5%. Of the 150 high-risk neonates, three (2%) and 95 (63%) were positive for ZIKV IgM and Flavivirus IgG antibodies, respectively. None of the three ZIKV IgM-positives had ³ 4 times higher anti-ZIKV neutralization titers than those against DENV-1 to 4 and JEV, and were therefore considered as probable CZI. Our results indicate that CZI is not rare in Vietnam. Although those with confirmed CZI did not show apparent symptoms suspected of congenital Zika syndrome at birth, detailed examinations and follow-up studies are needed to clarify the CZI impact in Vietnam. This is the first report of CZI cases in a birth cohort in Asia.

Zika virus screening during pregnancy: Results and lessons learned from a screening program and a post‐delivery follow‐up analysis (2016–2022)

“…Nearly half of them (45.5%) waited until the second or third trimester. This is according to the fact that migrant women in EU countries tend to access maternity care relatively late in their pregnancy (Ngwe Tun et al, 2020; Shen et al, 2021). Consequently, to overcome the socio‐cultural and administrative barriers that preclude, this access should be the first action to put in place (i.e., awareness‐raising and catch‐up activities).…”

“…The focus of ZIKV screening during pregnancy should be put on the detection of fetal infection. Based on the limited value of serology‐based screening and the fact that prolonged maternal viremia is associated with high risk of congenital ZIKV infection (Driggers et al, 2016), we propose to consider blood and/or urine PCR as the core initial testing test to be performed on all at‐risk women (Boerleider et al, 2015; Kikuti et al, 2018; Ngwe Tun et al, 2020; Rönnberg et al, 2017; Rowe et al, 2008; Shen et al, 2021; Venceslau et al, 2020). Altogether, including improved access to prenatal care for migrant women would increase the utility of the screening program in terms of early diagnosis of fetal abnormalities and closer follow‐up of women at high risk (Figure 2).…”

A Birth Cohort Follow-Up Study on Congenital Zika Virus Infection in Vietnam

“…We launched a birth cohort study and conducted a survey of neonates suspected of having congenital infections simultaneously at Khanh Hoa General Hospital (KHGH) in Nha Trang, the capital city in Khanh Hoa province, south-central Vietnam [ 17 , 18 ]. KHGH is a provincial hospital with approximately 6000 deliveries per year.…”

“…The plasma samples were also tested by a 50% focus reduction neutralization test for ZIKV, four serotypes of dengue virus, and Japanese encephalitis virus. RNA specimens extracted from the plasma samples were tested for ZIKV using quantitative reverse transcription polymerase chain reaction (qRT-PCR) to detect CZI [ 18 ]. We also tested the plasma samples for rubella-specific IgM, IgG, and cytomegalovirus-IgM.…”

“…We regarded a case as CZI in either case of ZIKV RNA detection in the cord or peripheral blood plasma or positive ZIKV IgM and neutralization test. The latter was considered significant when it was positive only against ZIKV, or when the neutralizing antibody titer against ZIKV was ≥4 times higher than those against other flaviviruses [ 18 ].…”