Prolonged Maternal Zika Viremia as a Marker of Adverse Perinatal Outcomes

Growth and Survival of a Cohort of Congenital Zika Virus Syndrome Children Born With Microcephaly and Children Who Developed With Microcephaly After Birth

BACKGROUND AND OBJECTIVES

Little is known about the clinical course of children born with congenital Zika virus syndrome (CZS). This article aimed to analyze the growth and survival of children with CZS born with microcephaly and children who developed with microcephaly after birth in the 36-month period.

METHODS

This is a cohort of children diagnosed with CZS who were monitored in a series of outpatient appointments, with clinical and demographic information and anthropometric measurements collected. The Mann-Kendall test evaluated the trend of the mean Z-score of head circumference (HC) for age and the Kaplan-Meier model described the time to low weight and short length according to the classification of HC at birth.

RESULTS

Children born without microcephaly had a reduction in HC growth velocity ( P = 0.019) and took longer to reach low weight ( P = 0.036) and short length ( P = 0.034) when compared with those born with microcephaly. Seven (10%) deaths were reported, and the probability of survival after 36 months of age was 88%. In children with arthrogryposis, the risk of death was 7 times as high as in those without this condition (adjusted hazard ratio: 6.49; 95% confidence interval: 1.31-32.20; P = 0.022).

CONCLUSIONS

In this cohort of children with CZS, 20% were born without microcephaly and all of them presented a reduction in HC growth velocity, which led to microcephaly. Progression to low weight and short length occurred in the first years of life, and that was faster in those born with microcephaly. Healthcare providers should be aware of these conditions that pose a risk of unfavorable anthropometric measurements and death.

Oropouche Virus (OROV) in Pregnancy: An Emerging Cause of Placental and Fetal Infection Associated with Stillbirth and Microcephaly following Vertical Transmission

Oropouche virus (OROV) is an emerging arbovirus endemic in Latin America and the Caribbean that causes Oropouche fever, a febrile illness that clinically resembles some other arboviral infections. It is currently spreading through Brazil and surrounding countries, where, from 1 January to 1 August 2024, more than 8000 cases have been identified in Bolivia, Brazil, Columbia, and Peru and for the first time in Cuba. Travelers with Oropouche fever have been identified in the United States and Europe. A significant occurrence during this epidemic has been the report of pregnant women infected with OROV who have had miscarriages and stillborn fetuses with placental, umbilical blood and fetal somatic organ samples that were RT-PCR positive for OROV and negative for other arboviruses. In addition, there have been four cases of newborn infants having microcephaly, in which the cerebrospinal fluid tested positive for IgM antibodies to OROV and negative for other arboviruses. This communication examines the biology, epidemiology, and clinical features of OROV, summarizes the 2023-2024 Oropouche virus epidemic, and describes the reported cases of vertical transmission and congenital infection, fetal death, and microcephaly in pregnant women with Oropouche fever, addresses experimental animal infections and potential placental pathology findings of OROV, and reviews other bunyavirus agents that can cause vertical transmission. Recommendations are made for pregnant women travelling to the regions affected by the epidemic.

Fetal MAVS and type I IFN signaling pathways control ZIKV infection in the placenta and maternal decidua

The contribution of placental immune responses to congenital Zika virus (ZIKV) syndrome remains poorly understood. Here, we leveraged a mouse model of ZIKV infection to identify mechanisms of innate immune restriction exclusively in the fetal compartment of the placenta. ZIKV principally infected mononuclear trophoblasts in the junctional zone, which was limited by mitochondrial antiviral-signaling protein (MAVS) and type I interferon (IFN) signaling mechanisms. Single nuclear RNA sequencing revealed MAVS-dependent expression of IFN-stimulated genes (ISGs) in spongiotrophoblasts but not in other placental cells that use alternate pathways to induce ISGs. ZIKV infection of Ifnar1-/- or Mavs-/- placentas was associated with greater infection of the adjacent immunocompetent decidua, and heterozygous Mavs+/- or Ifnar1+/- dams carrying immunodeficient fetuses sustained greater maternal viremia and tissue infection than dams carrying wild-type fetuses. Thus, MAVS-IFN signaling in the fetus restricts ZIKV infection in junctional zone trophoblasts, which modulates dissemination and outcome for both the fetus and the pregnant mother.

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

BACKGROUND

In response to the 2015-2016 Zika virus (ZIKV) outbreak and the causal relationship established between maternal ZIKV infection and adverse infant outcomes, we conducted a cohort study to estimate the incidence of ZIKV infection in pregnancy and assess its impacts in women and infants.

METHODOLOGY/PRINCIPAL FINDINGS

From May 2018-January 2020, we prospectively followed pregnant women recruited from 134 participating hospitals in two non-adjacent provinces in northeastern Thailand. We collected demographic, clinical, and epidemiologic data and blood and urine at routine antenatal care visits until delivery. ZIKV infections were confirmed by real-time reverse transcriptase polymerase chain reaction (rRT-PCR). Specimens with confirmed ZIKV underwent whole genome sequencing. Among 3,312 women enrolled, 12 (0.36%) had ZIKV infections, of which two (17%) were detected at enrollment. Ten (83%, 3 in 2nd and 7 in 3rd trimester) ZIKV infections were detected during study follow-up, resulting in an infection rate of 0.15 per 1,000 person-weeks (95% CI: 0.07-0.28). The majority (11/12, 91.7%) of infections occurred in one province. Persistent ZIKV viremia (42 days) was found in only one woman. Six women with confirmed ZIKV infections were asymptomatic until delivery. Sequencing of 8 ZIKV isolates revealed all were of Asian lineage. All 12 ZIKV infected women gave birth to live, full-term infants; the only observed adverse birth outcome was low birth weight in one (8%) infant. Pregnancies in 3,300 ZIKV-rRT-PCR-negative women were complicated by 101 (3%) fetal deaths, of which 67 (66%) had miscarriages and 34 (34%) had stillbirths. There were no differences between adverse fetal or birth outcomes of live infants born to ZIKV-rRT-PCR-positive mothers compared to live infants born to ZIKV-rRT-PCR-negative mothers.

CONCLUSIONS/SIGNIFICANCE

Confirmed ZIKV infections occurred infrequently in this large pregnancy cohort and observed adverse maternal and birth outcomes did not differ between mothers with and without confirmed infections.

Arboviruses and pregnancy: are the threats visible or hidden?

Mosquito-borne arboviral diseases are a global concern and can have severe consequences on maternal, neonatal, and child health. Their impact on pregnancy tends to be neglected in developing countries. Despite hundreds of millions of infections, 90% pregnancies being exposed, scientific data on pregnant women is poor and sometimes non-existent. Recently and since the 2016 Zika virus outbreak, there has been a newfound interest in these diseases. Through various neuropathogenic, visceral, placental, and teratogenic mechanisms, these arbovirus infections can lead to fetal losses, obstetrical complications, and a wide range of congenital abnormalities, resulting in long-term neurological and sensory impairments. Climate change, growing urbanization, worldwide interconnectivity, and ease of mobility allow arboviruses to spread to other territories and impact populations that had never been in contact with these emerging agents before. Pregnant travelers are also at risk of infection with potential subsequent complications. Beyond that, these pathologies show the inequalities of access to care on a global scale in a context of demographic growth and increasing urbanization. It is essential to promote research, diagnostic tools, treatments, and vaccine development to address this emerging threat.Background The vulnerability of pregnant women and fetuses to emergent and re-emergent pathogens has been notably illustrated by the outbreaks of Zika virus. Our comprehension of the complete scope and consequences of these infections during pregnancy remains limited, particularly among those involved in perinatal healthcare, such as obstetricians and midwives. This review aims to provide the latest information and recommendations regarding the various risks, management, and prevention for pregnant women exposed to arboviral infections.

Contrasted life trajectories: reconstituting the main population exposomes in French Guiana

In French Guiana, life expectancy is between 2 and 3 years below that of France, reflecting differences in mortality rates that are largely sensitive to primary healthcare and thus preventable. However, because poverty affects half of the population in French Guiana, global measurements of life expectancy presumably conflate at least two distinct situations: persons who have similar life expectancies as in mainland France and persons living in precariousness who have far greater mortality rates than their wealthier counterparts. We thus aimed to synthesize what is known about statistical regularities regarding exposures and sketch typical French Guiana exposomes in relation to health outcomes. We conducted a narrative review on common exposures in French Guiana and made comparisons between French Guiana and mainland France, between rich and poor in French Guiana, and between urban and rural areas within French Guiana. The most striking fact this panorama shows is that being a fetus or a young child in French Guiana is fraught with multiple threats. In French Guiana, poverty and poor pregnancy follow-up; renouncing healthcare; wide variety of infectious diseases; very high prevalence of food insecurity; psychosocial stress; micronutrient deficiencies; obesity and metabolic problems; and frequent exposure to lead and mercury in rural areas constitute a stunningly challenging exposome for a new human being to develop into. A substantial part of the population's health is hence affected by poverty and its sources of nutrition.

Infant mortality in French Guiana between 2001 and 2017 : Trends and comparisons with mainland France

BACKGROUND

French Guiana is a French overseas territory which combines a well-funded universal health system and a population where half are under the poverty line. In this context, we aimed to measure and describe the causes of infant mortality and, because French Guiana is a French territory, to compare them with mainland France.

METHODS

National death certificate data between 2001 and 2017 was used.

RESULTS

Overall, 6.9 % of deaths before 65 years concerned infants <1 year (in mainland France 2.6%). The infant mortality rate over the 2001-2017 period was 2.6 times that of mainland France (1159.5 vs 446.2 per 100,000 infants <1 year) with excess incidence in perinatal causes, malformations and chromosomal anomalies, accidents, infectious causes, and in poorly defined conditions. Over time, there seemed to be a reduction of infant mortality for all the main causes, except for congenital malformations and chromosomal anomalies, which, on the contrary, seemed to increase. The data sources did not allow to study the weight of social factors or place of residence.

CONCLUSIONS

All causes of infant mortality seemed to decline over time except malformations and chromosomal anomalies, which increased. Although exposure to heavy metals, infectious diseases are potential explanations we cannot pinpoint the cause of this increase with the available data. The present results suggest infant mortality and malformations should benefit from more detailed data sources in order to better assess and alleviate the burden of infant mortality in French Guiana.

Prenatal Zika virus infection has sex-specific effects on infant physical development and mother-infant social interactions

There is enormous variation in the extent to which fetal Zika virus (fZIKV) infection affects the developing brain. Despite the neural consequences of fZIKV infection observed in people and animal models, many open questions about the relationship between infection dynamics and fetal and infant development remain. To further understand how ZIKV affects the developing nervous system and the behavioral consequences of prenatal infection, we adopted a nonhuman primate model of fZIKV infection in which we inoculated pregnant rhesus macaques and their fetuses with ZIKV in the early second trimester of fetal development. We then tracked their health across gestation and characterized infant development across the first month of life. ZIKV-infected pregnant mothers had long periods of viremia and mild changes to their hematological profiles. ZIKV RNA concentrations, an indicator of infection magnitude, were higher in mothers whose fetuses were male, and the magnitude of ZIKV RNA in the mothers' plasma or amniotic fluid predicted infant outcomes. The magnitude of ZIKV RNA was negatively associated with infant growth across the first month of life, affecting males' growth more than females' growth, although for most metrics, both males and females evidenced slower growth rates as compared with control animals whose mothers were not ZIKV inoculated. Compared with control infants, fZIKV infants also spent more time with their mothers during the first month of life, a social behavior difference that may have long-lasting consequences on psychosocial development during childhood.

Control of maternal Zika virus infection during pregnancy is associated with lower antibody titers in a macaque model

Introduction

Zika virus (ZIKV) infection during pregnancy results in a spectrum of birth defects and neurodevelopmental deficits in prenatally exposed infants, with no clear understanding of why some pregnancies are more severely affected. Differential control of maternal ZIKV infection may explain the spectrum of adverse outcomes.

Methods

Here, we investigated whether the magnitude and breadth of the maternal ZIKV-specific antibody response is associated with better virologic control using a rhesus macaque model of prenatal ZIKV infection. We inoculated 18 dams with an Asian-lineage ZIKV isolate (PRVABC59) at 30-45 gestational days. Plasma vRNA and infectious virus kinetics were determined over the course of pregnancy, as well as vRNA burden in the maternal-fetal interface (MFI) at delivery. Binding and neutralizing antibody assays were performed to determine the magnitude of the ZIKV-specific IgM and IgG antibody responses throughout pregnancy, along with peptide microarray assays to define the breadth of linear ZIKV epitopes recognized.

Results

Dams with better virologic control (n= 9) cleared detectable infectious virus and vRNA from the plasma by 7 days post-infection (DPI) and had a lower vRNA burden in the MFI at delivery. In comparison, dams with worse virologic control (n= 9) still cleared detectable infectious virus from the plasma by 7 DPI but had vRNA that persisted longer, and had higher vRNA burden in the MFI at delivery. The magnitudes of the ZIKV-specific antibody responses were significantly lower in the dams with better virologic control, suggesting that higher antibody titers are not associated with better control of ZIKV infection. Additionally, the breadth of the ZIKV linear epitopes recognized did not differ between the dams with better and worse control of ZIKV infection.

Discussion

Thus, the magnitude and breadth of the maternal antibody responses do not seem to impact maternal virologic control. This may be because control of maternal infection is determined in the first 7 DPI, when detectable infectious virus is present and before robust antibody responses are generated. However, the presence of higher ZIKV-specific antibody titers in dams with worse virologic control suggests that these could be used as a biomarker of poor maternal control of infection and should be explored further.

Fetal loss in pregnant rhesus macaques infected with high-dose African-lineage Zika virus

Countermeasures against Zika virus (ZIKV), including vaccines, are frequently tested in nonhuman primates (NHP). Macaque models are important for understanding how ZIKV infections impact human pregnancy due to similarities in placental development. The lack of consistent adverse pregnancy outcomes in ZIKV-affected pregnancies poses a challenge in macaque studies where group sizes are often small (4-8 animals). Studies in small animal models suggest that African-lineage Zika viruses can cause more frequent and severe fetal outcomes. No adverse outcomes were observed in macaques exposed to 1x104 PFU (low dose) of African-lineage ZIKV at gestational day (GD) 45. Here, we exposed eight pregnant rhesus macaques to 1x108 PFU (high dose) of African-lineage ZIKV at GD 45 to test the hypothesis that adverse pregnancy outcomes are dose-dependent. Three of eight pregnancies ended prematurely with fetal death. ZIKV was detected in both fetal and placental tissues from all cases of early fetal loss. Further refinements of this exposure system (e.g., varying the dose and timing of infection) could lead to an even more consistent, unambiguous fetal loss phenotype for assessing ZIKV countermeasures in pregnancy. These data demonstrate that high-dose exposure to African-lineage ZIKV causes pregnancy loss in macaques and also suggest that ZIKV-induced first trimester pregnancy loss could be strain-specific.

About the need to address pediatric health inequalities in French Guiana : a scoping review

INTRODUCTION

French Guiana is a French overseas territory in South America, marked by poverty and inequalities. Access to different services, including healthcare, is unequal depending on where people live. Several studies showed that among adults, the most precarious individuals had greater incidences of chronic and infectious diseases. Although the median age of the population living in this territory is 25, there is no specific focus on the pediatric population although it is documented that socioeconomic inequalities have an impact on child health. The objective of this scoping review is to shed light on health challenges concerning children living in French Guiana.

METHODS

A literature search was performed on PubMed to identify relevant articles, and additional references were added if within the scope of this review.

RESULTS

A total of 106 publications were reviewed. Perinatal health issues were linked to a high rate of teenage pregnancies with poor medical follow-up leading to complications such as preterm deliveries and congenital malformations and abnormalities. Infectious diseases were a significant burden with worrisome vaccination coverage figures for some bacterial infections, partly explaining a high mortality rate attributable to infectious diseases. Herbicide poisoning with paraquat was reported in children, and environment-related concerns such as wild animal attacks as well as lead and mercury exposure were reported. Some children living in remote Amerindian communities had a higher suicide rate than in mainland France, and chronic diseases such as sickle cell disease were reported to have more transfusion-related complications.

CONCLUSION

Children living in French Guiana have worse pediatric health indicators in comparison with children from mainland France.

Zika virus impacts extracellular vesicle composition and cellular gene expression in macaque early gestation trophoblasts

Zika virus (ZIKV) infection at the maternal-placental interface is associated with adverse pregnancy outcomes including fetal demise and pregnancy loss. To determine how infection impacts placental trophoblasts, we utilized rhesus macaque trophoblast stem cells (TSC) that can be differentiated into early gestation syncytiotrophoblasts (ST) and extravillous trophoblasts (EVT). TSCs and STs, but not EVTs, were highly permissive to productive infection with ZIKV strain DAK AR 41524. The impact of ZIKV on the cellular transcriptome showed that infection of TSCs and STs increased expression of immune related genes, including those involved in type I and type III interferon responses. ZIKV exposure altered extracellular vesicle (EV) mRNA, miRNA and protein cargo, including ZIKV proteins, regardless of productive infection. These findings suggest that early gestation macaque TSCs and STs are permissive to ZIKV infection, and that EV analysis may provide a foundation for identifying non-invasive biomarkers of placental infection in a highly translational model.

Neonatal Development in Prenatally Zika Virus-Exposed Infant Macaques with Dengue Immunity

Infants exposed to Zika virus (ZIKV) prenatally may develop birth defects, developmental deficits, or remain asymptomatic. It is unclear why some infants are more affected than others, although enhancement of maternal ZIKV infection via immunity to an antigenically similar virus, dengue virus (DENV), may play a role. We hypothesized that DENV immunity may worsen prenatal ZIKV infection and developmental deficits in offspring. We utilized a translational macaque model to examine how maternal DENV immunity influences ZIKV-exposed infant macaque neurodevelopment in the first month of life. We inoculated eight macaques with prior DENV infection with ZIKV, five macaques with ZIKV, and four macaques with saline. DENV/ZIKV-exposed infants had significantly worse visual orientation skills than ZIKV-exposed infants whose mothers were DENV-naive, with no differences in motor, sensory or state control development. ZIKV infection characteristics and pregnancy outcomes did not individually differ between dams with and without DENV immunity, but when multiple factors were combined in a multivariate model, maternal DENV immunity combined with ZIKV infection characteristics and pregnancy parameters predicted select developmental outcomes. We demonstrate that maternal DENV immunity exacerbates visual orientation and tracking deficits in ZIKV-exposed infant macaques, suggesting that human studies should evaluate how maternal DENV immunity impacts long-term neurodevelopment.