Lack of Association between Adverse Pregnancy Outcomes and Zika Antibodies among Pregnant Women in Thailand between 1997 and 2015

Abstract

Data about Zika virus infection and adverse pregnancy outcomes in Southeast Asia are scarce. We conducted an unmatched case-control study of Zika virus (ZIKV) serology in pregnant women enrolled in human immunodeficiency virus (HIV) or hepatitis B virus (HBV) perinatal prevention trials between 1997 and 2015 in Thailand. Case and control groups included women with and without adverse pregnancy outcomes. Plasma samples collected during the last trimester of pregnancy were tested for ZIKV IgG/IgM and Dengue IgG/IgM (Euroimmun, AG, Germany). Case newborn plasma samples were tested for ZIKV IgM and ZIKV RNA (Viasure, Spain). The case group included women with stillbirth (n = 22) or whose infants had microcephaly (n = 4), a head circumference below the first percentile (n = 14), neurological disorders (n = 36), or had died within 10 days after birth (n = 11). No women in the case group were positive for ZIKV IgM, and none of their live-born neonates were positive for ZIKV IgM or ZIKV RNA. The overall ZIKV IgG prevalence was 29%, 24% in the case and 34% in the control groups (Fisher’s exact test; p = 0.13), while the dengue IgG seroprevalence was 90%. Neither neonatal ZIKV infections nor ZIKV-related adverse pregnancy outcomes were observed in these women with HIV and/or HBV during the 18-year study period.

Zika Virus Immunoglobulin G Seroprevalence among Young Adults Living with HIV or without HIV in Thailand from 1997 to 2017

“…ZIKV IgG seroprevalence was stable, ranging from 24.3 to 27.4% during 1997-2017. These results are consistent with the overall ZIKV IgG seroprevalence of 29% found in HIV-or HBV-infected pregnant women with a median age of 25.2 years in Thailand during 1997-2015 [23]. Our data of ZIKV IgG seroprevalence in the 1997-2000 period suggests that ZIKV was circulating in Thailand before 1997, which supports findings by Ponds et al of ZIKV positive serology in Thailand since 1954 [12].…”

Zika Virus from the Perspective of Observational Studies: a Review

“…In the case of Thailand however, between 1997–2015 prevention of perinatal transmission of HIV and HBV was studied. The samples from the study were stored and later used by Ngo-Giang-Huong et al ( 43 ) in an unmatched case-control study to explore the relationship between adverse outcomes of pregnancy and the presence of ZIKV antibodies in the subjects. The participants included a case group of pregnant women and a control group without adverse pregnancy outcomes, and their infants.…”

“…Most of the data collected from the observational studies involve the effects of ZIKV on neonates ( 32 – 41 , 43 – 48 ), whereas only a limited number of studies have highlighted its effect on adults ( 49 – 55 ). Furthermore, most of these observational studies regarding ZIKV have emerged from South America, particularly Brazil ( 32 – 41 ).…”

Characteristics, risk factors, and outcomes related to Zika virus infection during pregnancy in Northeastern Thailand: A prospective pregnancy cohort study, 2018–2020

“…No significant differences in incidence or outcomes were detected before and after the change in eligibility criteria based on gestational age in our study. Other studies in Southeast Asia have also found no association between ZIKV infection during pregnancy and adverse neonatal outcomes, including microcephaly [ 68 , 69 ] There is still limited understanding about why the pathogenicity of ZIKV infection in Southeast Asia appears to be less severe than ZIKV infection in the Americas.…”