Adverse birth outcomes associated with Zika virus exposure during pregnancy in São José do Rio Preto, Brazil

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.

Neuroinflammation, blood-brain barrier dysfunction, hippocampal atrophy and delayed neurodevelopment: Contributions for a rat model of congenital Zika syndrome

The congenital Zika syndrome (CZS) has been characterized as a set of several brain changes, such as reduced brain volume and subcortical calcifications, in addition to cognitive deficits. Microcephaly is one of the possible complications found in newborns exposed to Zika virus (ZIKV) during pregnancy, although it is an impacting clinical sign. This study aimed to investigate the consequences of a model of congenital ZIKV infection by evaluating the histopathology, blood-brain barrier, and neuroinflammation in pup rats 24 h after birth, and neurodevelopment of the offspring. Pregnant rats were inoculated subcutaneously with ZIKV-BR at the dose 1 × 107 plaque-forming unit (PFU mL-1) of ZIKV isolated in Brazil (ZIKV-BR) on gestational day 18 (G18). A set of pups, 24 h after birth, was euthanized. The brain was collected and later evaluated for the histopathology of brain structures through histological analysis. Additionally, analyses of the blood-brain barrier were conducted using western blotting, and neuroinflammation was assessed using ELISA. Another set of animals was evaluated on postnatal days 3, 6, 9, and 12 for neurodevelopment by observing the developmental milestones. Our results revealed hippocampal atrophy in ZIKV animals, in addition to changes in the blood-brain barrier structure and pro-inflammatory cytokines expression increase. Regarding neurodevelopment, a delay in important reflexes during the neonatal period in ZIKV animals was observed. These findings advance the understanding of the pathophysiology of CZS and contribute to enhancing the rat model of CZS.

Congenital Zika Virus Syndrome: Microcephaly and Orofacial Anomalies

The progressive reappearance of Zika virus (ZIKV) infections since October 2013 and its circulation in >70 countries and territories (from French Polynesia to Brazil and other countries in the Americas, with sporadic spread in Europe and the East) has long been reported as a global public health emergency. ZIKV is a virus transmitted by arthropods (arboviruses), mainly by Aedes mosquitoes. ZIKV can also be transmitted to humans through mechanisms other than vector infection such as sexual intercourse, blood transfusions, and mother-to-child transmission. The latter mode of transmission can give rise to a severe clinical form called congenital Zika syndrome (CZS), which can result in spontaneous abortion or serious pathological alterations in the fetus such as microcephaly or neurological and orofacial anomalies. In this study, beside a succinct overview of the etiological, microbiological, and epidemiological aspects and modes of transmission of Zika virus infections, we have focused our attention on the pathogenetic and histopathological aspects in pregnancy and the pathogenetic and molecular mechanisms that can determine microcephaly, and consequently the clinical alterations, typical of the fetus and newborns, in a subject affected by CZS.

Offspring affected with in utero Zika virus infection retain molecular footprints in the bone marrow and blood cells

Congenital virus infections, for example cytomegalovirus and rubella virus infections, commonly affect the central nervous and hematological systems in fetuses and offspring. However, interactions between emerging congenital Zika virus and hematological system-bone marrow and blood-in fetuses and offspring are mainly unknown. Our overall goal was to determine whether silent in utero Zika virus infection can cause functional and molecular footprints in the bone marrow and blood of fetuses and offspring. We specifically focused on silent fetal infection because delayed health complications in initially asymptomatic offspring were previously demonstrated in animal and human studies. Using a well-established porcine model for Zika virus infection and a set of cellular and molecular experimental tools, we showed that silent in utero infection causes multi-organ inflammation in fetuses and local inflammation in the fetal bone marrow. In utero infection also caused footprints in the offspring bone marrow and PBMCs. These findings should be considered in a broader clinical context because of growing concerns about health sequelae in cohorts of children affected with congenital Zika virus infection in the Americas. Understanding virus-induced molecular mechanisms of immune activation and inflammation in fetuses may provide targets for early in utero interventions. Also, identifying early biomarkers of in utero-acquired immunopathology in offspring may help to alleviate long-term sequelae.

Dengue Vaccination: Towards a New Dawn of Curbing Dengue Infection

Dengue is an infectious disease caused by dengue virus (DENV) and is a serious global burden. Antibody-dependent enhancement and the ability of DENV to infect immune cells, along with other factors, lead to fatal Dengue Haemorrhagic Fever and Dengue Shock Syndrome. This necessitates the development of a robust and efficient vaccine but vaccine development faces a number of hurdles. In this review, we look at the epidemiology, genome structure and cellular targets of DENV and elaborate upon the immune responses generated by human immune system against DENV infection. The review further sheds light on various challenges in development of a potent vaccine against DENV which is followed by presenting a current account of different vaccines which are being developed or have been licensed.

A comprehensive insight on the challenges for COVID-19 vaccine: A lesson learnt from other viral vaccines

The aim of this study is to comprehensively analyze previous viral vaccine programs and identify potential challenges and effective measures for the COVID-19 vaccine program. Previous viral vaccine programs, such as those for HIV, Zika, Influenza, Ebola, Dengue, SARS, and MERS, were evaluated. Paramount challenges were identified, including quasi-species, cross-reactivity, duration of immunity, revaccination, mutation, immunosenescence, and adverse events related to viral vaccines. Although a large population has been vaccinated, mutations in SARS-CoV-2 and adverse events related to vaccines pose significant challenges. Previous vaccine programs have taught us that predicting the final outcome of the current vaccine program for COVID-19 cannot be determined at a given state. Long-term follow-up studies are essential. Validated preclinical studies, long-term follow-up studies, alternative therapeutic approaches, and alternative vaccines are necessary.

The prevalence of IGM antibodies to Zika virus in pregnant women in Northern Nigeria

INTRODUCTION

Zika virus (ZIKV) infection during pregnancy can result in severe outcomes for both the pregnant woman and the developing fetus. The objective of this study was to investigate the prevalence of Zika virus infection among pregnant women who sought healthcare services at Ahmadu Bello University Teaching Hospital.

MATERIALS AND METHODS

Serum samples were collected and analyzed using Enzyme Linked Immunoassay and RT-qPCR methods, while a structured questionnaire was used to gather relevant information about the participants.

RESULTS

The results showed that 53 out of the 180 pregnant women tested positive for Anti-Zika IgM antibodies, which represents a 29.4% prevalence rate. Subsequent RT-qPCR analysis found that only 6 out of the 53 positive samples contained Zika virus RNA. Fever and headache were the most commonly reported symptoms related to the infection.

CONCLUSION

These findings indicate a potential outbreak of Zika fever in Northern Nigeria emphasizing the importance for pregnant women to take precautions to avoid getting infected.

Clinical and experimental evidence for transplacental vertical transmission of flaviviruses

The Zika virus (ZIKV) epidemic outbreak in Americas in 2016 attracted global attention because of the association of the virus infection with severe birth defects such as microcephaly, mediated through transplacental virus transmission during pregnancy. Less well-known, but also reported is the increasing evidence that prenatal vertical transmission can be caused by other flaviviruses such as dengue virus (DENV). Currently, the mechanism(s) that cause the vertical transmission of flaviviruses is understudied. Here we review the published reports of clinical evidence of intrauterine transmission of ZIKV and other flaviviruses. We also discuss the animal models for flavivirus infection during pregnancy that have been developed to study the mechanisms underlying the transplacental transmission of flaviviruses in order to develop potential countermeasures for its prevention.

Risk of adverse outcomes in offspring with RT-PCR confirmed prenatal Zika virus exposure: An individual participant data meta-analysis of 13 cohorts in the Zika Brazilian Cohorts Consortium

Background

Knowledge regarding the risks associated with Zika virus (ZIKV) infections in pregnancy has relied on individual studies with relatively small sample sizes and variable risk estimates of adverse outcomes, or on surveillance or routinely collected data. Using data from the Zika Brazilian Cohorts Consortium, this study aims, to estimate the risk of adverse outcomes among offspring of women with RT-PCR-confirmed ZIKV infection during pregnancy and to explore heterogeneity between studies.

Methods

We performed an individual participant data meta-analysis of the offspring of 1548 pregnant women from 13 studies, using one and two-stage meta-analyses to estimate the absolute risks.

Findings

Of the 1548 ZIKV-exposed pregnancies, the risk of miscarriage was 0.9%, while the risk of stillbirth was 0.3%. Among the pregnancies with liveborn children, the risk of prematurity was 10,5%, the risk of low birth weight was 7.7, and the risk of small for gestational age (SGA) was 16.2%. For other abnormalities, the absolute risks were: 2.6% for microcephaly at birth or first evaluation, 4.0% for microcephaly at any time during follow-up, 7.9% for neuroimaging abnormalities, 18.7% for functional neurological abnormalities, 4.0% for ophthalmic abnormalities, 6.4% for auditory abnormalities, 0.6% for arthrogryposis, and 1.5% for dysphagia. This risk was similar in all sites studied and in different socioeconomic conditions, indicating that there are not likely to be other factors modifying this association.

Interpretation

This study based on prospectively collected data generates the most robust evidence to date on the risks of congenital ZIKV infections over the early life course. Overall, approximately one-third of liveborn children with prenatal ZIKV exposure presented with at least one abnormality compatible with congenital infection, while the risk to present with at least two abnormalities in combination was less than 1.0%.

Diagnostic accuracy of prenatal imaging for the diagnosis of congenital Zika syndrome: Systematic review and meta-analysis

Objective

The aim of this study was to assess the accuracy of prenatal imaging for the diagnosis of congenital Zika syndrome.

Data sources

Medline (via Pubmed), PubMed, Scopus, Web of Science, and Google Scholar from inception to March 2022. Two researchers independently screened study titles and abstracts for eligibility.

Study eligibility criteria

Observational studies with Zika virus-infected pregnant women were included. The index tests included ultrasound and/or magnetic resonance imaging. The reference standard included (1) Zika infection-related perinatal death, stillbirth, and neonatal death within the first 48 h of birth, (2) neonatal intensive care unit admission, and (3) clinically defined adverse perinatal outcomes.

Synthesis methods

We extracted 2 × 2 contingency tables. Pooled sensitivity and specificity were estimated using the random-effects bivariate model and assessed the summary receiver operating characteristic (ROC) curve. Risk of bias was assessed using QUADAS 2 tool. The certainty of the evidence was evaluated with grading of recommendations.

Results

We screened 1,459 references and included 18 studies (2359 pregnant women, 347 fetuses with confirmed Zika virus infection). Twelve studies (67%) were prospective cohorts/case series, and six (37%) were retrospective cohort/case series investigations. Fourteen studies (78%) were performed in endemic regions. Ten studies (56%) used prenatal ultrasound only, six (33%) employed ultrasound and fetal MRI, and two studies (11%) used prenatal ultrasound and postnatal fetal MRI. A total of six studies (ultrasound only) encompassing 780 pregnant women (122 fetuses with confirmed Zika virus infection) reported relevant data for meta-analysis (gestation age at which ultrasound imagining was captured ranged from 16 to 34 weeks). There was large heterogeneity across studies regarding sensitivity (range: 12 to 100%) and specificity (range: 50 to 100%). Under a random-effects model, the summary sensitivity of ultrasound was 82% (95% CI, 19 to 99%), and the summary specificity was 97% (71 to 100%). The area under the ROC curve was 97% (95% CI, 72 to 100%), and the summary diagnostic odds ratio was 140 (95% CI, 3 to 7564, P < 0.001). The overall certainty of the evidence was “very low”.

Conclusion

Ultrasound may be useful in improving the diagnostic accuracy of Zika virus infection in pregnancy. However, the evidence is still substantially uncertain due to the methodological limitations of the available studies. Larger, properly conducted diagnostic accuracy studies of prenatal imaging for the diagnosis of congenital Zika syndrome are warranted.

Systematic review registration

Identifier [CRD42020162914].

Early and mid-gestation Zika virus (ZIKV) infection in the olive baboon (Papio anubis) leads to fetal CNS pathology by term gestation

Zika virus (ZIKV) infection in pregnancy can produce catastrophic teratogenic damage to the developing fetus including microcephaly and congenital Zika syndrome (CZS). We previously described fetal CNS pathology occurring by three weeks post-ZIKV inoculation in Olive baboons at mid-gestation, including neuroinflammation, loss of radial glia (RG), RG fibers, neuroprogenitor cells (NPCs) resulting in disrupted NPC migration. In the present study, we explored fetal brain pathologies at term gestation resulting from ZIKV exposure during either first or second trimester in the Olive baboon. In all dams, vRNA in whole blood resolved after 7 days post inoculation (dpi). One first trimester infected dam aborted at 5 dpi. All dams developed IgM and IgG response to ZIKV with ZIKV IgG detected in fetal serum. Placental pathology and inflammation were observed including disruption of syncytiotrophoblast layers, delayed villous maturation, partially or fully thrombosed vessels, calcium mineralization and fibrin deposits. In the uterus, ZIKV was detected in ¾ first trimester but not in second trimester infected dams. While ZIKV was not detected in any fetal tissue at term, all fetuses exhibited varying degrees of neuropathology. Fetal brains from ZIKV inoculated dams exhibited a range of gross brain pathologies including irregularities of the major gyri and sulci of the cerebral cortex and cerebellar pathology. Frontal cortices of ZIKV fetuses showed a general disorganization of the six-layered cortex with degree of disorganization varying among the fetuses from the two groups. Frontal cortices from ZIKV inoculation in the first but not second trimester exhibited increased microglia, and in both trimester ZIKV inoculation, increased astrocyte numbers (white matter). In the cerebellum, increased microglia were observed in fetuses from both first and second trimester inoculation. In first trimester ZIKV inoculation, decreased oligodendrocyte precursor cell populations were observed in fetal cerebellar white matter. In general, our observations are in accordance with those described in human ZIKV infected fetuses.

Arboviral Infections in Neurological Disorders in Hospitalized Patients in São José do Rio Preto, São Paulo, Brazil

Arbovirus infections are increasingly important causes of disease, whose spectrum of neurological manifestations are not fully known. This study sought to retrospectively assess the incidence of arboviruses in cerebrospinal fluid samples of patients with neurological symptoms to inform diagnosis of central and peripheral nervous system disorders. A total of 255 cerebrospinal fluid (CSF) samples collected from January 2016 to December 2017 were tested for dengue virus (DENV 1-4), Zika virus (ZIKV), and Chikungunya virus (CHIKV) in addition to other neurotropic arboviruses of interest, using genetic and serologic assays. Of the 255 CSF samples analyzed, 3.53% (09/255) were positive for arboviruses presenting mainly as meningitis, encephalitis, and cerebrovascular events, of which ZIKV was detected in 2.74% (7/255), DENV in 0.78% (2/255), in addition to an identified ILHV infection that was described previously. All the cases were detected in adults aged 18 to 74 years old. Our findings highlight the scientific and clinical importance of neurological syndromes associated with arboviruses and demonstrate the relevance of specific laboratory methods to achieve accurate diagnoses as well as highlight the true dimension of these diseases to ultimately improve public health planning and medical case management.

ZIKV can infect human term placentas in the absence of maternal factors

Zika virus infection can result in devastating pregnancy outcomes when it crosses the placental barrier. For human pregnancies, the mechanisms of vertical transmission remain enigmatic. Utilizing a human placenta-cotyledon perfusion model, we examined Zika virus exposure in the absence of maternal factors. To distinguish responses related to viral infection vs. recognition, we evaluated cotyledons perfused with either active or inactivated Zika virus. Active Zika virus exposure resulted in infection, cell death and syncytium injury. Pathology corresponded with transcriptional changes related to inflammation and innate immunity. Inactive Zika virus exposure also led to syncytium injury and related changes in gene expression but not cell death. Our observations reveal pathologies and innate immune responses that are dependent on infection or virus placenta interactions independent of productive infection. Importantly, our findings indicate that Zika virus can infect and compromise placentas in the absence of maternal humoral factors that may be protective.

Villazana-Kretzer et al. compare histology, physiology and gene expression in cotyledons from term placentas perfused with either active or UV-inactivated Zika virus. They show that ZIKV can infect human term placentas in the absence of maternal factors and identify unique transcriptional responses to active ZIKA virus.

Zika Virus Infection of Pregnant Ifnar1-/- Mice Triggers Strain-Specific Differences in Fetal Outcomes

Zika virus (ZIKV) is a flavivirus that causes a constellation of adverse fetal outcomes collectively termed congenital Zika syndrome (CZS). However, not all pregnancies exposed to ZIKV result in an infant with apparent defects. During the 2015 to 2016 American outbreak of ZIKV, CZS rates varied by geographic location. The underlying mechanisms responsible for this heterogeneity in outcomes have not been well defined. Therefore, we sought to characterize and compare the pathogenic potential of multiple Asian-/American-lineage ZIKV strains in an established Ifnar1-/- pregnant mouse model. Here, we show significant differences in the rate of fetal demise following maternal inoculation with ZIKV strains from Puerto Rico, Panama, Mexico, Brazil, and Cambodia. Rates of fetal demise broadly correlated with maternal viremia but were independent of fetus and placenta virus titer, indicating that additional underlying factors contribute to fetal outcome. Our results, in concert with those from other studies, suggest that subtle differences in ZIKV strains may have important phenotypic impacts. With ZIKV now endemic in the Americas, greater emphasis needs to be placed on elucidating and understanding the underlying mechanisms that contribute to fetal outcome. IMPORTANCE Zika virus (ZIKV) transmission has been reported in 87 countries and territories around the globe. ZIKV infection during pregnancy is associated with adverse fetal outcomes, including birth defects, microcephaly, neurological complications, and even spontaneous abortion. Rates of adverse fetal outcomes vary between regions, and not every pregnancy exposed to ZIKV results in birth defects. Not much is known about how or if the infecting ZIKV strain is linked to fetal outcomes. Our research provides evidence of phenotypic heterogeneity between Asian-/American-lineage ZIKV strains and provides insight into the underlying causes of adverse fetal outcomes. Understanding ZIKV strain-dependent pathogenic potential during pregnancy and elucidating underlying causes of diverse clinical sequelae observed during human infections is critical to understanding ZIKV on a global scale.

Intrauterine exposure to Zika virus and hearing loss within the first few years of life: A systematic literature review

BACKGROUND

Identification of the factors that could potentially lead to congenital hearing loss is of paramount importance, as early detection of congenital hearing loss and intervention could prevent developmental delays in speech, language development as well as childhood cognitive impairment. Hitherto, intrauterine exposure to Zika virus has emerged as a cause of various fetal malformations, including cases of congenital hearing loss. The aim of this systematic review is to investigate the association between intrauterine exposure to Zika virus and hearing loss in children.

METHODS

A systematic literature search was conducted to the databases PubMed, Cochrane library, Scopus, ClinicalTrials.gov, SciELO and Lilacs in order to identify studies that examine the association between prenatally Zika exposure and hearing loss within the first few years of life. Studies were eligible for inclusion, if solely objective methods for hearing evaluation of patients such as otoacoustic emissions (OAEs) and/or auditory brainstem response (ABR) were used, in children who intrauterine exposed to the Zika virus.

RESULTS

Thirteen studies were included, which included 1275 children who are prenatally exposed to Zika virus. In 852 of the cases an objective hearing evaluation was performed using either OAEs or ABR. 709 children were tested with ABR and 79 had a failed outcome. 143 children were tested with OAEs whilst of these, 30 had a failed outcome. Altered OAEs ranged from 8.7% to 30.2%, while altered ABR ranged from 0% to 19.9%. The initial sample includes 428 children with microcephaly, while 5 of the studies comprise microcephaly to the inclusion criteria.

CONCLUSION

It seems to be a possible association between prenatal Zika virus exposure and hearing loss in children during the first years of their life. It is of great importance that in future studies possible confounding factors, like microcephaly, will be appropriately controlled. Additionally, the follow-up period of monitoring hearing loss in children should be prolonged in order to identify potential late onset hearing problems caused by intrauterine exposure to Zika virus.

Cranial US in Infants Exposed to Zika Virus: The NATZIG Cohort

Background Studies addressing neuroimaging findings as primary outcomes of congenital Zika virus infection are variable regarding inclusion criteria and confirmatory laboratory testing. Purpose To investigate cranial US signs of prenatal Zika virus exposure and to describe frequencies of cranial US findings in infants exposed to Zika virus compared to those in control infants. Materials and Methods In this single-center prospective cohort study, participants were enrolled during the December 2015-July 2016 outbreak of Zika virus infection in southeast Brazil (Natural History of Zika Virus Infection in Gestation cohort). Eligibility criteria were available cranial US and laboratory findings of maternal Zika virus infection during pregnancy confirmed with RNA polymerase chain reaction testing (ie, Zika virus-exposed infants). The control group was derived from the Zika in Infants and Pregnancy cohort and consisted of infants born to asymptomatic pregnant women who tested negative for Zika virus infection during pregnancy. Two radiologists who were blinded to the maternal Zika virus infection status independently reviewed cranial US scans from both groups and categorized them as normal findings, Zika virus-like pattern, or mild findings. Associations between cranial US findings and prenatal Zika virus exposure were assessed with univariable analysis. Results Two hundred twenty Zika virus-exposed infants (mean age, 53.3 days ± 71.1 [standard deviation]; 113 boys) and born to 219 mothers infected with Zika virus were included in this study and compared with 170 control infants (mean age, 45.6 days ± 45.8; 102 boys). Eleven of the 220 Zika virus-exposed infants (5%), but no control infants, had a Zika virus-like pattern at cranial US. No difference in frequency of mild findings was observed between the groups (50 of 220 infants [23%] vs 44 of 170 infants [26%], respectively; P = .35). The mild finding of lenticulostriate vasculopathy, however, was nine times more frequent in Zika virus-exposed infants (12 of 220 infants, 6%) than in control infants (one of 170 infants, 1%) (P = .01). Conclusion Lenticulostriate vasculopathy was more common after prenatal exposure to Zika virus, even in infants with normal head size, despite otherwise overall similar frequency of mild cranial US findings in Zika virus-exposed infants and in control infants. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Benson in this issue.

Epidemic preparedness: Prenatal Zika virus screening during the next epidemic

Zika virus (ZIKV) is a vectorborne infectious agent of global public health significance due to its potential to cause severe teratogenic outcomes. The question of whether health systems should consider adopting screening programmes for ZIKV infections during pregnancy warrants consideration. In this analysis, we apply the Wilson-Jungner framework to appraise the potential utility of a prenatal ZIKV screening programme, outline potential screening strategies within the case-finding pathway, and consider other epidemiological factors that may influence the planning of such a screening programme. Our evaluation of a potential prenatal ZIKV screening programme highlights factors affirming its usefulness, including the importance of Congenital Zika Syndrome as a public health problem and the existence of analogous congenital prenatal screening programmes for STORCH agents (syphilis, toxoplasmosis, others (eg, human immunodeficiency virus, varicella-zoster virus, parvovirus B19), rubella, cytomegalovirus, and herpes simplex virus). However, our assessment also reveals key barriers to implementation, such as the need for more accurate diagnostic tests, effective antiviral treatments, increased social service capacity, and surveillance. Given that the reemergence of ZIKV is likely, we provide a guiding framework for policymakers and public health leaders that can be further elaborated and adapted to different contexts in order to reduce the burden of adverse ZIKV-related birth outcomes during future outbreaks.

Why Did ZIKV Perinatal Outcomes Differ in Distinct Regions of Brazil? An Exploratory Study of Two Cohorts

The Zika virus (ZIKV) epidemic in Brazil occurred in regions where dengue viruses (DENV) are historically endemic. We investigated the differences in adverse pregnancy/infant outcomes in two cohorts comprising 114 pregnant women with PCR-confirmed ZIKV infection in Rio de Janeiro, Southeastern Brazil (n = 50) and Manaus, in the north region of the country (n = 64). Prior exposure to DENV was evaluated through plaque reduction neutralizing antibody assays (PRNT 80) and DENV IgG serologies. Potential associations between pregnancy outcomes and Zika attack rates in the two cities were explored. Overall, 31 women (27%) had adverse pregnancy/infant outcomes, 27 in Rio (54%) and 4 in Manaus (6%), p < 0.001. This included 4 pregnancy losses (13%) and 27 infants with abnormalities at birth (24%). A total of 93 women (82%) had evidence of prior DENV exposure, 45 in Rio (90%) and 48 in Manaus (75%). Zika attack rates differed; the rate in Rio was 10.28 cases/10,000 and in Manaus, 0.6 cases/10,000, p < 0.001. Only Zika attack rates (Odds Ratio: 17.6, 95% Confidence Interval 5.6–55.9, p < 0.001) and infection in the first trimester of pregnancy (OR: 4.26, 95% CI 1.4–12.9, p = 0.011) were associated with adverse pregnancy and infant outcomes. Pre-existing immunity to DENV was not associated with outcomes (normal or abnormal) in patients with ZIKV infection during pregnancy.

Vertical transmission of Zika virus and its outcomes: a Bayesian synthesis of prospective studies

BACKGROUND

Prospective studies of Zika virus in pregnancy have reported rates of congenital Zika syndrome and other adverse outcomes by trimester. However, Zika virus can infect and damage the fetus early in utero, but clear before delivery. The true vertical transmission rate is therefore unknown. We aimed to provide the first estimates of underlying vertical transmission rates and adverse outcomes due to congenital infection with Zika virus by trimester of exposure.

METHODS

This was a Bayesian latent class analysis of data from seven prospective studies of Zika virus in pregnancy. We estimated vertical transmission rates, rates of Zika-virus-related and non-Zika-virus-related adverse outcomes, and the diagnostic sensitivity of markers of congenital infection. We allowed for variation between studies in these parameters and used information from women in comparison groups with no PCR-confirmed infection, where available.

FINDINGS

The estimated mean risk of vertical transmission was 47% (95% credible interval 26 to 76) following maternal infection in the first trimester, 28% (15 to 46) in the second, and 25% (13 to 47) in the third. 9% (4 to 17) of deliveries following infections in the first trimester had symptoms consistent with congenital Zika syndrome, 3% (1 to 7) in the second, and 1% (0 to 3) in the third. We estimated that in infections during the first, second, and third trimester, respectively, 13% (2 to 27), 3% (-5 to 14), and 0% (-7 to 11) of pregnancies had adverse outcomes attributable to Zika virus infection. Diagnostic sensitivity of markers of congenital infection was lowest in the first trimester (42% [18 to 72]), but increased to 85% (51 to 99) in trimester two, and 80% (42 to 99) in trimester three. There was substantial between-study variation in the risks of vertical transmission and congenital Zika syndrome.

INTERPRETATION

This preliminary analysis recovers the causal effects of Zika virus from disparate study designs. Higher transmission in the first trimester is unusual with congenital infections but accords with laboratory evidence of decreasing susceptibility of placental cells to infection during pregnancy.

FUNDING

European Union Horizon 2020 programme.

Three-Year Clinical Follow-Up of Children Intrauterine Exposed to Zika Virus

Congenital Zika virus (ZIKV) infection may present with a broad spectrum of clinical manifestations. Some sequelae, particularly neurodevelopmental problems, may have a later onset. We conducted a prospective cohort study of 799 high-risk pregnant women who were followed up until delivery. Eighty-three women and/or newborns were considered ZIKV exposed and/or infected. Laboratory diagnosis was made by polymerase chain reaction in the pregnant mothers and their respective newborns, as well as Dengue virus, Chikungunya virus, and ZIKV serology. Serology for toxoplasmosis, rubella, cytomegalovirus, herpes simplex virus, and syphilis infections were also performed in microcephalic newborns. The newborns included in the study were followed up until their third birthday. Developmental delay was observed in nine patients (13.2%): mild cognitive delay in three patients, speech delay in three patients, autism spectrum disorder in two patients, and severe neurological abnormalities in one microcephalic patient; sensorineural hearing loss, three patients and dysphagia, six patients. Microcephaly due to ZIKV occurred in three patients (3.6%). Clinical manifestations can appear after the first year of life in children infected/exposed to ZIKV, emphasizing the need for long-term follow-up.

Zika-related adverse outcomes in a cohort of pregnant women with rash in Pernambuco, Brazil

Background

While Zika virus (ZIKV) is now widely recognized as a teratogen, the frequency and full spectrum of adverse outcomes of congenital ZIKV infection remains incompletely understood.

Methods

Participants in the MERG cohort of pregnant women with rash, recruited from the surveillance system from December/2015-June/2017. Exposure definition was based on a combination of longitudinal data from molecular, serologic (IgM and IgG3) and plaque reduction neutralization tests for ZIKV. Children were evaluated by a team of clinical specialists and by transfontanelle ultrasound and were classified as having microcephaly and/or other signs/symptoms consistent with congenital Zika syndrome (CZS). Risks of adverse outcomes were quantified according to the relative evidence of a ZIKV infection in pregnancy.

Findings

376 women had confirmed and suspected exposure to ZIKV. Among evaluable children born to these mothers, 20% presented with an adverse outcome compatible with exposure to ZIKV during pregnancy. The absolute risk of microcephaly was 2.9% (11/376), of calcifications and/or ventriculomegaly was 7.2% (13/180), of additional neurologic alterations was 5.3% (13/245), of ophthalmologic abnormalities was 7% (15/214), and of dysphagia was 1.8% (4/226). Less than 1% of the children experienced abnormalities across all of the domains simultaneously. Interpretation: Although approximately one-fifth of children with confirmed and suspected exposure to ZIKV in pregnancy presented with at least one abnormality compatible with CZS, the manifestations presented more frequently in isolation than in combination. Due to the rare nature of some outcomes and the possibility of later manifestations, large scale individual participant data meta-analysis and the long-term evaluation of children are imperative to identify the full spectrum of this syndrome and to plan actions to reduce damages.

The ability to meaningfully quantify the absolute and relative risks of Congenital Zika Syndrome is contingent on the accurate identification of ZIKV infections in pregnant women and the long-term follow-up of children at risk. This study builds on the evidence base on ZIKV in pregnancy by not only examining pregnancy and birth outcomes, but also considering later onset manifestations of Congenital Zika Syndrome, conducting a deep and standardized investigation of infant outcomes. In addition, it used unprecedented repeated testing and the use of multiple diagnostic platforms, including qRT-PCR, IgM and IgG3 ELISAs, and PRNTs to identify ZIKV cases. The absolute risk of microcephaly was 2.9%, of calcifications and/or ventriculomegaly was 7.2%, of additional neurologic alterations was 5.3%, of ophthalmologic abnormalities was 7% and of dysphagia was 1.8%. The manifestations presented more frequently in isolation than in combination (i.e., less than 1% of the children experienced abnormalities across all of the domains simultaneously). Although approximately one-fifth of children with confirmed and suspected exposure to ZIKV in pregnancy presented with at least one abnormality compatible with CZS, the manifestations presented more frequently in isolation than in combination

Zika Virus Neutralizing Antibody Kinetics in Antenatally Exposed Infants

BACKGROUND

Zika virus (ZIKV) is associated with severe congenital abnormalities and laboratory diagnosis of antenatal infection is difficult. Here we evaluated ZIKV neutralizing antibody (Nab) kinetics in infants born to mothers with PCR-confirmed ZIKV infection during pregnancy.

METHODS

Neonates (n=98) had serum specimens tested repeatedly for ZIKV Nab over the first two years of life using virus neutralization test (VNT). ZIKV neonatal infection was confirmed by RT-PCR in blood or urine and/or presence of ZIKV IgM antibodies, and results were correlated with infant clinical features.

RESULTS

Postnatal laboratory evidence of ZIKV vertical transmission was obtained for 60.2% of children, while 32.7% exhibited clinical abnormalities. Congenital abnormalities were found in 37.3% of children with confirmed ZIKV infection and 31.0% of children without confirmed infection (p=0.734). All but one child displayed a physiologic decline in ZIKV Nab, reflecting maternal antibody decay, despite an early ZIKV-IgM response in 1/3 of infants.

CONCLUSIONS

Infants with antenatal ZIKV exposure do not develop ZIKV Nab despite an early IgM response. Therefore, ZIKV VNT in children is not useful for diagnosis of congenital infection. In light of these findings, it remains to be determined if children infected in utero are potentially susceptible to reinfection.

Zika virus infection in pregnancy: a protocol for the joint analysis of the prospective cohort studies of the ZIKAlliance, ZikaPLAN and ZIKAction consortia

INTRODUCTION

Zika virus (ZIKV) infection in pregnancy has been associated with microcephaly and severe neurological damage to the fetus. Our aim is to document the risks of adverse pregnancy and birth outcomes and the prevalence of laboratory markers of congenital infection in deliveries to women experiencing ZIKV infection during pregnancy, using data from European Commission-funded prospective cohort studies in 20 centres in 11 countries across Latin America and the Caribbean.

METHODS AND ANALYSIS

We will carry out a centre-by-centre analysis of the risks of adverse pregnancy and birth outcomes, comparing women with confirmed and suspected ZIKV infection in pregnancy to those with no evidence of infection in pregnancy. We will document the proportion of deliveries in which laboratory markers of congenital infection were present. Finally, we will investigate the associations of trimester of maternal infection in pregnancy, presence or absence of maternal symptoms of acute ZIKV infection and previous flavivirus infections with adverse outcomes and with markers of congenital infection. Centre-specific estimates will be pooled using a two-stage approach.

ETHICS AND DISSEMINATION

Ethical approval was obtained at each centre. Findings will be presented at international conferences and published in peer-reviewed open access journals and discussed with local public health officials and representatives of the national Ministries of Health, Pan American Health Organization and WHO involved with ZIKV prevention and control activities.

Zika Virus Infection in a Cohort of Pregnant Women with Exanthematic Disease in Manaus, Brazilian Amazon

The epidemic transmission of Zika virus (ZIKV) in Brazil has been identified as a cause of microcephaly and other neurological malformations in the babies of ZIKV-infected women. The frequency of adverse outcomes of Zika virus infection (ZIKVi) in pregnancy differs depending on the characteristics of exposure to infection, the time of recruitment of research participants, and the outcomes to be observed. This study provides a descriptive analysis—from the onset of symptoms to delivery—of a cohort registered as having maternal ZIKVi in pregnancy, from November 2015 to December 2016. Suspected cases were registered at a referral center for infectious and tropical diseases in Manaus, in the Amazonian region of Brazil. Of 834 women notified, 762 women with confirmed pregnancies were enrolled. Reverse-transcriptase polymerase chain reaction (RT-PCR) confirmed ZIKVi in 42.3% of the cohort. In 35.2% of the cohort, ZIKV was the sole infection identified. Severe adverse pregnancy outcomes (miscarriage, stillbirth, or microcephaly) were observed in both RT-PCR ZIKV-positive (5.0%) and ZIKV-negative (1.8%) cases (RR 3.1; 95% IC 1.4–7.3; p < 0.05), especially during the first trimester of pregnancy (RR 6.2, 95% IC 2.3–16.5; p < 0.001). Although other infectious rash diseases were observed in the pregnant women in the study, having confirmed maternal ZIKVi was the most important risk factor for serious adverse pregnancy events.

Can Zika Virus Infection in High Risk Pregnant Women Be Differentiated on the Basis of Symptoms?

Zika virus (ZIKV) infection in pregnancy is associated with congenital neurological abnormalities. Our understanding of the full clinical spectrum of ZIKV infection is incomplete. Using data from this prospective cohort study consisting of 650 women attending a high-risk pregnancy clinic during the Zika virus outbreak in Brazil, we investigated the extent to which specific symptoms can be utilized to differentiate ZIKV-infected pregnant women from those with other pregnancy-related problems. All were tested for ZIKV in urine by RT-qPCR. Demographic and clinical data including physical symptoms during follow-up were recorded and analyzed with respect to Zika virus exposure status. Forty-eight (7.4%) women were positive for ZIKV by RT-qPCR. The majority (70.8%) were asymptomatic, and only four ZIKV-positive women (8.3%) reported symptoms during pregnancy that met the WHO case definition. Zika-positive and -negative women reported similar frequencies of ZIKV-like symptoms (as per the WHO definition): fever (16.7% vs. 13.6%), arthralgia/arthritis (10.4% vs. 11.3%), rash (4.2% vs. 5.3%), and conjunctivitis (2.1% vs. 3.2%). Most pregnant women positive for ZIKV in urine are asymptomatic and do not deliver a baby with microcephaly. Physical symptoms alone did not differentiate between high-risk pregnant women positive or negative for ZIKV.

Speech-language disorders in children with congenital Zika virus syndrome: A systematic review

INTRODUCTION

Having verified the true association between the Zika virus and the occurrence of microcephaly, studies were conducted to evaluate the effects of the infection on fetal development. Congenital Zika virus syndrome is a currently known condition but little addressed regarding speech, language, and hearing disorders in children.

OBJECTIVE

To conduct a systematic review of speech, language, and hearing disorders in children with congenital Zika virus syndrome.

METHODS

This systematic review followed the PRISMA instructions and the Joanna Briggs Institute guidelines, and it was registered in PROSPERO (CRD42018111764). The databases consulted were Cochrane, SciELO, PubMed, LILACS, Scopus, Web of Science, and ScienceDirect. OpenGrey and OpenThesis were used to partially capture the "grey literature". Observational studies of children with microcephaly due to congenital Zika virus syndrome were included. The risk of bias was analyzed using the 2017 Joanna Briggs Institute.

RESULTS

707 records were obtained and, after excluding the duplicates, 644 studies remained. After applying the inclusion criteria, 24 articles were considered eligible. Children with congenital Zika virus syndrome presented abnormal persistence of primitive reflexes (94.7%), impaired cognitive development (95.1%), delayed neuropsychomotor development (between 92.8 and 100%), hypertonia (between 74.7% and 90.1%), impaired language development (between 68.42% and 100%), retrognathia (38.6%), craniofacial disproportion (between 32.9% and 95.8%), altered tongue frenulum (between 30% and 36.36%), the absence of stapedial reflexes (27.3%), dysphagia (between 14% and 88.9%), and hearing changes (between 5.8% and 68.42%).

CONCLUSION

Children with congenital Zika virus syndrome may have speech, language, and hearing disorders such as hearing loss, dysphagia, alteration in the tongue frenulum, and delays in neuropsychomotor and language development.

Postnatal symptomatic Zika virus infections in children and adolescents: A systematic review

BACKGROUND

Recent Zika virus (ZIKV) outbreaks in the Pacific and the Americas have highlighted clinically significant congenital neurological abnormalities resulting from ZIKV infection in pregnancy. However, little is known about ZIKV infections in children and adolescents, a group that is potentially vulnerable to ZIKV neurovirulence.

METHODS

We conducted a systematic review on the clinical presentation and complications of children and adolescents aged 0 to 18 years with a robust diagnosis of ZIKV infection. We searched PubMed, Web of Science, LILACs, and EMBASE until 13 February 2020 and screened reference lists of eligible articles. We assessed the studies' risk of bias using pre-specified criteria.

FINDINGS

Our review collated the evidence from 2543 pediatric ZIKV cases representing 17 countries and territories, identified in 1 cohort study, 9 case series and 22 case reports. The most commonly observed signs and symptoms of ZIKV infection in children and adolescents were mild and included fever, rash, conjunctivitis and arthralgia. The frequency of neurological complications was reported only in the largest case series (identified in 1.0% of cases) and in an additional 14 children identified from hospital-based surveillance studies and case reports. ZIKV-related mortality was primarily accompanied by co-morbidity and was reported in one case series (<0.5% of cases) and three case reports. One death was attributed to complications of Guillain-Barré Syndrome secondary to ZIKV infection.

CONCLUSIONS AND RELEVANCE

Based on the current evidence, the clinical presentation of ZIKV infection in children and adolescents appears to be primarily mild and similar to the presentation in adults, with rare instances of severe complications and/or mortality. However, reliable estimation of the risks of ZIKV complications in these age groups is limited by the scarcity and quality of published data. Additional prospective studies are needed to improve understanding of the relative frequency of the signs, symptoms, and complications associated with pediatric ZIKV infections and to investigate any potential effects of early life ZIKV exposure on neurodevelopment.

Early Growth Parameters as Predictors of Developmental Delay Among Children Conceived During the 2015-2016 Zika Virus Outbreak in Northeastern Brazil

Background: Identifying infants with congenital infection for early intervention will likely be challenging in future Zika virus outbreaks. We investigated indicators of risk for developmental delay among children born with and without obvious manifestations of congenital Zika virus infection. Methods: We evaluated 120 children conceived during the 2015−2016 Zika virus outbreak in Paraíba, Brazil. We analyzed data from children at birth; ages 1−7 months and approximately 24 months, using medical records (i.e., anthropometric measurements diagnoses), medical evaluation (i.e., Zika/other laboratory tests, dysmorphic features), and parent report (seizures, developmental delay). We used a Bayesian modeling approach to identify predictors of developmental delay. Results: Head circumference (HC) and length at birth and rates of growth for HC and length at follow-up were consistent across domains of developmental delay; (e.g., for every 1 cm per month decrease in HC growth rate; there was a corresponding decrease in the gross motor z-score). Modeling results indicated that HC and length at birth, and follow-up HC and length rates of growth, were predictive of developmental delay. Conclusion: These findings suggest that accurate measurement and frequent monitoring of HC and length, especially in the first few months of life, may be useful for identifying children possibly congenitally exposed to Zika virus who could benefit from early intervention services.

Normal Hearing Function in Children Prenatally Exposed to Zika Virus

Introduction  The association between prenatal Zika virus infection and hearing alterations in offspring has been the object of some studies, although few have assessed children without microcephaly. However, a current trend to include prenatal Zika virus exposure in the group of risk indicators for hearing loss is noted. Objective  To present a series of 27 children prenatally exposed to the Zika virus submitted to multiple hearing assessments over time. Methods  A cohort of children born to symptomatic mothers with laboratorial Zika virus infection confirmation during pregnancy was submitted to an otoacoustic emission test, auditory brainstem response test (automated, neurodiagnostic and frequency-specific), audiometry, and imitanciometry over a period of 36 months since birth. The hearing assessment was performed independently of the presence of microcephaly or other apparent signs of congenital Zika syndrome. Results  The hearing tests presented predominantly normal results. Some children had signs of middle ear pathology. The only microcephalic child had normal electrophysiological tests, as well as preserved audiometric thresholds, but presented altered motor responses to sound. Conclusion  Prenatal exposure to Zika virus does not always determine hearing impairment. This risk seems to be more associated to the severity of the central nervous system damage. Hearing screening and follow-ups of the affected children are important, as well as further research in this area.

Functional Outcomes among a Cohort of Children in Northeastern Brazil Meeting Criteria for Follow-Up of Congenital Zika Virus Infection

Following the large outbreak of Zika virus in the Western Hemisphere, many infants have been born with congenital Zika virus infection. It is important to describe the functional outcomes seen with congenital infections to allow for their recognition and appropriate interventions. We evaluated 120 children conceived during the 2015-2016 Zika virus outbreak in Paraíba, Brazil, who were approximately 24 months old, to assess functional outcomes. All children met either anthropometric criteria or laboratory criteria suggestive of possible congenital Zika virus infection. We collected results of previous medical evaluations, interviewed parents, and performed physical examinations and functional assessments, for example, the Hammersmith Infant Neurological Examination (HINE). We compared patterns of neurologic outcomes and developmental delay at age 24 months by whether children met anthropometric or laboratory criteria, or both. Among children meeting both criteria, 60% (26/43) were multiply affected (had severe motor impairment, severe developmental delay, and suboptimal HINE scores), compared with 5% (3/57) meeting only laboratory criteria and none (0/20) meeting only anthropometric criteria. Of the remaining 91 children, 49% (45) had developmental delay, with more severe delay seen in children meeting both criteria. Although children meeting physical and laboratory criteria for potential congenital Zika virus infection were more severely affected, we did identify several children with notable adverse neurologic outcomes and developmental delay with no physical findings but potential laboratory evidence of Zika virus infection. Given this, all children who were potentially exposed in utero to Zika virus should be monitored in early childhood for deficits to allow for early intervention.

Flavivirus Infection Associated with Cerebrovascular Events

Arthropod-borne viruses (arboviruses) of the genus Flavivirus are distributed globally and cause significant human disease and mortality annually. Flavivirus infections present a spectrum of clinical manifestations, ranging from asymptomatic to severe manifestations, including hemorrhage, encephalitis and death. Herein, we describe 3 case reports of cerebrovascular involvement in patients infected by dengue and Zika viruses in Sao Jose do Rio Preto, São Paulo State, Brazil, a hyperendemic area for arbovirus circulation, including dengue, yellow fever, chikungunya and Saint Louis encephalitis viruses. Our findings highlight the potential threat that unusual clinical manifestations may pose to arbovirus disease management and recovery.

Challenges in Dengue Vaccines Development: Pre-existing Infections and Cross-Reactivity

Dengue is one of the most frequently transmitted mosquito-borne diseases in the world, which creates a significant public health concern globally, especially in tropical and subtropical countries. It is estimated that more than 390 million people are infected with dengue virus each year and around 96 million develop clinical pathologies. Dengue infections are not only a health problem but also a substantial economic burden. To date, there are no effective antiviral therapies and there is only one licensed dengue vaccine that only demonstrated protection in the seropositive (Immune), naturally infected with dengue, but not dengue seronegative (Naïve) vaccines. In this review, we address several immune components and their interplay with the dengue virus. Additionally, we summarize the literature pertaining to current dengue vaccine development and advances. Moreover, we review some of the factors affecting vaccine responses, such as the pre-vaccination environment, and provide an overview of the significant challenges that face the development of an efficient/protective dengue vaccine including the presence of multiple serotypes, antibody-dependent enhancement (ADE), as well as cross-reactivity with other flaviviruses. Finally, we discuss targeting T follicular helper cells (Tfh), a significant cell population that is essential for the production of high-affinity antibodies, which might be one of the elements needed to be specifically targeted to enhance vaccine precision to dengue regardless of dengue serostatus.

Clinical Outcomes of a Zika Virus Mother-Child Pair Cohort in Spain

Background: Zika virus (ZIKV) infection has been associated with congenital microcephaly and other neurodevelopmental abnormalities. There is little published research on the effect of maternal ZIKV infection in a non-endemic European region. We aimed to describe the outcomes of pregnant travelers diagnosed as ZIKV-infected in Spain, and their exposed children. Methods: This prospective observational cohort study of nine referral hospitals enrolled pregnant women (PW) who travelled to endemic areas during their pregnancy or the two previous months, or those whose sexual partners visited endemic areas in the previous 6 months. Infants of ZIKV-infected mothers were followed for about two years. Results: ZIKV infection was diagnosed in 163 PW; 112 (70%) were asymptomatic and 24 (14.7%) were confirmed cases. Among 143 infants, 14 (9.8%) had adverse outcomes during follow-up; three had a congenital Zika syndrome (CZS), and 11 other potential Zika-related outcomes. The overall incidence of CZS was 2.1% (95%CI: 0.4–6.0%), but among infants born to ZIKV-confirmed mothers, this increased to 15.8% (95%CI: 3.4–39.6%). Conclusions: A nearly 10% overall risk of neurologic and hearing adverse outcomes was found in ZIKV-exposed children born to a ZIKV-infected traveler PW. Longer-term follow-up of these children is needed to assess whether there are any later-onset manifestations.

The frequency and clinical presentation of Zika virus coinfections: a systematic review

BACKGROUND

There is limited knowledge on the influence of concurrent coinfections on the clinical presentation of Zika virus (ZIKV) disease.

METHODS

To better understand the types, frequencies and clinical manifestations of ZIKV coinfections, we did a systematic review of four databases (PubMed, Embase, Web of Science, LILACS) without restrictions for studies on ZIKV coinfections confirmed by nucleic acid (quantitative real-time-PCR) testing of ZIKV and coinfecting pathogens. The review aimed to identify cohort, cross-sectional, case series and case report studies that described frequencies and/or clinical signs and symptoms of ZIKV coinfections. Conference abstracts, reviews, commentaries and studies with imprecise pathogen diagnoses and/or no clinical evaluations were excluded.

RESULTS

The search identified 34 articles from 10 countries, comprising 2 cohort, 10 cross-sectional, 8 case series and 14 case report studies. Coinfections were most frequently reported to have occurred with other arthropod-borne viruses (arboviruses); out of the 213 coinfections described, ZIKV infections co-occurred with chikungunya in 115 cases, with dengue in 68 cases and with both viruses in 19 cases. Other coinfecting agents included human immunodeficiency, Epstein-Barr, human herpes and Mayaro viruses, Leptospira spp, Toxoplasma gondii and Schistosoma mansoni. ZIKV-coinfected cases primarily presented with mild clinical features, typical of ZIKV monoinfection; however, 9% of cases in cohort and cross-sectional studies were reported to experience complications.

CONCLUSION

Based on the evidence collated in this review, coinfections do not appear to strongly influence the clinical manifestations of uncomplicated ZIKV infections. Further research is needed to confirm whether risk of severe complications is altered when ZIKV infection co-occurs with other infections.

PROSPERO REGISTRATION NUMBER

CRD42018111023.

Single cell immune profiling of dengue virus patients reveals intact immune responses to Zika virus with enrichment of innate immune signatures

The genus Flavivirus contains many mosquito-borne human pathogens of global epidemiological importance such as dengue virus, West Nile virus, and Zika virus, which has recently emerged at epidemic levels. Infections with these viruses result in divergent clinical outcomes ranging from asymptomatic to fatal. Myriad factors influence infection severity including exposure, immune status and pathogen/host genetics. Furthermore, pre-existing infection may skew immune pathways or divert immune resources. We profiled immune cells from dengue virus-infected individuals by multiparameter mass cytometry (CyTOF) to define functional status. Elevations in IFNβ were noted in acute patients across the majority of cell types and were statistically elevated in 31 of 36 cell subsets. We quantified response to in vitro (re)infection with dengue or Zika viruses and detected a striking pattern of upregulation of responses to Zika infection by innate cell types which was not noted in response to dengue virus. Significance was discovered by statistical analysis as well as a neural network-based clustering approach which identified unusual cell subsets overlooked by conventional manual gating. Of public health importance, patient cells showed significant enrichment of innate cell responses to Zika virus indicating an intact and robust anti-Zika response despite the concurrent dengue infection.

Researching Zika in pregnancy: lessons for global preparedness

Our understanding of congenital infections is based on prospective studies of women infected during pregnancy. The EU has funded three consortia to study Zika virus, each including a prospective study of pregnant women. Another multi-centre study has been funded by the US National Institutes of Health. This Personal View describes the study designs required to research Zika virus, and questions whether funding academics in the EU and USA to work with collaborators in outbreak areas is an effective strategy. 3 years after the 2015-16 Zika virus outbreaks, these collaborations have taught us little about vertical transmission of the virus. In the time taken to approve funding, agree contracts, secure ethics approval, and equip laboratories, Zika virus had largely disappeared. By contrast, prospective studies based on local surveillance and standard-of-care protocols have already provided valuable data. Threats to fetal and child health pose new challenges for global preparedness requiring support for the design and implementation of locally appropriate protocols. These protocols can answer the key questions earlier than externally designed studies and at lower cost. Local protocols can also provide a framework for recruitment of unexposed controls that are required to study less specific outcomes. Other priorities include accelerated development of non-invasive tests, and longer-term storage of neonatal and antenatal samples to facilitate retrospective reconstruction of cohort studies.

A neonatal nonhuman primate model of gestational Zika virus infection with evidence of microencephaly, seizures and cardiomyopathy

Zika virus infection during pregnancy is associated with miscarriage and with a broad spectrum of fetal and neonatal developmental abnormalities collectively known as congenital Zika syndrome (CZS). Symptomology of CZS includes malformations of the brain and skull, neurodevelopmental delay, seizures, joint contractures, hearing loss and visual impairment. Previous studies of Zika virus in pregnant rhesus macaques (Macaca mulatta) have described injury to the developing fetus and pregnancy loss, but neonatal outcomes following fetal Zika virus exposure have yet to be characterized in nonhuman primates. Herein we describe the presentation of rhesus macaque neonates with a spectrum of clinical outcomes, including one infant with CZS-like symptoms including cardiomyopathy, motor delay and seizure activity following maternal infection with Zika virus during the first trimester of pregnancy. Further characterization of this neonatal nonhuman primate model of gestational Zika virus infection will provide opportunities to evaluate the efficacy of pre- and postnatal therapeutics for gestational Zika virus infection and CZS.

Cross-Reactive Antibodies during Zika Virus Infection: Protection, Pathogenesis, and Placental Seeding

Humoral immunity is an essential component of the protective immune response to flavivirus infection. Typically, primary infection generates a robust neutralizing antibody response that mediates viral control and protection. It is becoming increasingly apparent that secondary infection with a closely related flavivirus strain can result in immunological cross-reactivity; however, the consequences to infection outcome remain controversial. Since its introduction to Brazil in 2015, Zika virus (ZIKV) has caused an epidemic of fetal congenital malformations within the Americas. Because ZIKV is a mosquito-borne flavivirus with a high degree of sequence and structural homology to Dengue virus (DENV), the role of immunological cross-reactivity in ZIKV and DENV infections has become a great concern. In this review, we highlight contemporary findings that implicate a role for flavivirus antibodies in mediating protection, contributing to pathogenesis, and seeding the human placenta.

Maternal Zika Virus Infection: Association With Small-for-Gestational-Age Neonates and Preterm Birth

OBJECTIVE

To evaluate whether antenatal Zika virus infection is associated with risk of having a small-for-gestational-age (SGA) neonate, risk of preterm birth, and lower mean birth weight of term neonates.

METHODS

For this retrospective observational study, we linked birth record data for women who delivered liveborn singleton neonates in New York City in 2016 to data for pregnant women with Zika virus infection reported to the New York City Health Department. We restricted the analysis to nonsmoking, nonwhite women and adjusted for maternal characteristics. Among women with antenatal Zika virus infection, we used modified Poisson regression to assess risks of having an SGA neonate and of delivering preterm, and linear regression to assess the association of infection with mean birth weight of term neonates.

RESULTS

Of 116,034 deliveries of singleton neonates in New York City in 2016, 251 (0.2%) were to women with antenatal Zika virus infection. A higher percentage of women with Zika virus infection delivered an SGA neonate compared with those without (11.2% vs 5.8%; adjusted relative risk [RR] 1.8; 95% CI 1.3-2.6). There was no difference in preterm birth prevalence for women with and without Zika virus infection (adjusted RR 1.0; 95% CI 0.69-1.6). Mean birth weight of term neonates born to women with Zika virus infection was 47 g less (95% CI -105 to 11 g); this difference was not statistically significant in crude or adjusted analyses.

CONCLUSION

For a cohort of New York City women, antenatal Zika virus infection was associated with an increased risk of having an SGA neonate, but not preterm birth or lower mean birth weight of term neonates. This supports a putative association between Zika virus infection during pregnancy and SGA.

Subclinical in utero Zika virus infection is associated with interferon alpha sequelae and sex-specific molecular brain pathology in asymptomatic porcine offspring

Zika virus (ZIKV) infection during human pregnancy may lead to severe fetal pathology and debilitating impairments in offspring. However, the majority of infections are subclinical and not associated with evident birth defects. Potentially detrimental life-long health outcomes in asymptomatic offspring evoke high concerns. Thus, animal models addressing sequelae in offspring may provide valuable information. To induce subclinical infection, we inoculated selected porcine fetuses at the mid-stage of development. Inoculation resulted in trans-fetal virus spread and persistent infection in the placenta and fetal membranes for two months. Offspring did not show congenital Zika syndrome (e.g., microcephaly, brain calcifications, congenital clubfoot, arthrogryposis, seizures) or other visible birth defects. However, a month after birth, a portion of offspring exhibited excessive interferon alpha (IFN-α) levels in blood plasma in a regular environment. Most affected offspring also showed dramatic IFN-α shutdown during social stress providing the first evidence for the cumulative impact of prenatal ZIKV exposure and postnatal environmental insult. Other eleven cytokines tested before and after stress were not altered suggesting the specific IFN-α pathology. While brains from offspring did not have histopathology, lesions, and ZIKV, the whole genome expression analysis of the prefrontal cortex revealed profound sex-specific transcriptional changes that most probably was the result of subclinical in utero infection. RNA-seq analysis in the placenta persistently infected with ZIKV provided independent support for the sex-specific pattern of in utero-acquired transcriptional responses. Collectively, our results provide strong evidence that two hallmarks of fetal ZIKV infection, altered type I IFN response and molecular brain pathology can persist after birth in offspring in the absence of congenital Zika syndrome.

A number of studies showed that Zika virus (ZIKV) can cause severe abnormalities in fetuses, e.g., brain lesions, and subsequently life-long developmental and cognitive impairment in children. However, the majority of infections in pregnant women are subclinical and are not associated with developmental abnormalities in fetuses and newborns. It is known that disruptions to the in utero environment during fetal development can program increased risks for disease in adulthood. For this reason, children affected in utero even by mild ZIKV infection can appear deceptively healthy at birth but develop immune dysfunction and brain abnormalities during postnatal development. Here, we used the porcine model of subclinical fetal ZIKV infection to determine health sequelae in offspring which did not show apparent signs of the disease. We demonstrated that subclinical fetal infection was associated with abnormal immunological responses in apparently healthy offspring under normal environmental conditions and during social stress. We also showed silent sex-specific brain pathology as represented by altered gene expression. Our study provides new insights into potential outcomes of subclinical in utero ZIKV infection. It also emphasizes that further attempts to better understand silent pathology and develop alleviative interventions in ZIKV-affected offspring should take into account interactions of host factors, like sex, and environmental insults, like social stress.

Detection of Zika virus in paired urine and amniotic fluid samples from symptomatic and asymptomatic women and their babies during a disease outbreak: association with neurological symptoms in newborns

Paired maternal and newborn urine and amniotic fluid from 138 subjects collected during a Zika virus (ZIKV) outbreak was analyzed for ZIKV by gene amplification (RT-qPCR), and the findings were correlated with clinical symptoms and neurological anomalies in the babies. ZIKV was detected in 1 of 9 symptomatic women (11.1%) and in 19 of 129 asymptomatic women (14.7%). Neurological manifestations were present in 19 babies (13.7%), 10 of 20 (50%) positive and 9 of 119 (7.6%) negative (p < 0.001) for ZIKV. Twelve (8.6%) urines collected during gestation were ZIKV-positive; only 2 remained positive for ZIKV postpartum. Six (4.1%) newborn urines collected within 1 day of delivery were ZIKV-positive cases. In 3 of these cases, ZIKV was detected in mother’s urine pre- and postpartum and in both mother’s urine and babies’ urine. Four of the amniotic fluid samples (2.9%) were ZIKV-positive. Among ZIKV-negative babies with neurological sequel, 87.5% were female; in contrast, 72.7% ZIKV-positive babies with neurological abnormalities were male (p = 0.019). We conclude that during a ZIKV outbreak, clinical symptoms and ZIKV detection in biological fluids are poor predictors of infection and adverse neurologic sequel in newborns.

Zika virus infection as a cause of congenital brain abnormalities and Guillain-Barré syndrome: A living systematic review

Background: The Zika virus (ZIKV) caused a large outbreak in the Americas leading to the declaration of a Public Health Emergency of International Concern in February 2016. A causal relation between infection and adverse congenital outcomes such as microcephaly was declared by the World Health Organization (WHO) informed by a systematic review structured according to a framework of ten dimensions of causality, based on the work of Bradford Hill. Subsequently, the evidence has continued to accumulate, which we incorporate in regular updates of the original work, rendering it a living systematic review.

Methods: We present an update of our living systematic review on the causal relation between ZIKV infection and adverse congenital outcomes and between ZIKV and GBS for four dimensions of causality: strength of association, dose-response, specificity, and consistency. We assess the evidence published between January 18, 2017 and July 1, 2019.

Results: We found that the strength of association between ZIKV infection and adverse outcomes from case-control studies differs according to whether exposure to ZIKV is assessed in the mother (OR 3.8, 95% CI: 1.7-8.7, I ²=19.8%) or the foetus/infant (OR 37.4, 95% CI: 11.0-127.1, I ²=0%). In cohort studies, the risk of congenital abnormalities was 3.5 times higher after ZIKV infection (95% CI: 0.9-13.5, I ²=0%). The strength of association between ZIKV infection and GBS was higher in studies that enrolled controls from hospital (OR: 55.8, 95% CI: 17.2-181.7, I ²=0%) than in studies that enrolled controls at random from the same community or household (OR: 2.0, 95% CI: 0.8-5.4, I ²=74.6%). In case-control studies, selection of controls from hospitals could have biased results.

Conclusions: The conclusions that ZIKV infection causes adverse congenital outcomes and GBS are reinforced with the evidence published between January 18, 2017 and July 1, 2019.

Delayed childhood neurodevelopment and neurosensory alterations in the second year of life in a prospective cohort of ZIKV-exposed children

We report neurodevelopmental outcomes in 216 infants followed since the time of PCR-confirmed maternal Zika virus (ZIKV) infection in pregnancy during the Rio de Janeiro epidemic of 2015-2016 (refs. 1,2). Neurodevelopment was assessed by Bayley Scales of Infant and Toddler Development, third edition (Bayley-III; cognitive, language and motor domains) in 146 children and through neurodevelopment questionnaires/neurological examinations in 70 remaining children. Complete eye exams (n = 137) and hearing assessments (n = 114) were also performed. Below-average neurodevelopment and/or abnormal eye or hearing assessments were noted in 31.5% of children between 7 and 32 months of age. Among children assessed by Bayley-III, 12% scored below -2 s.d. (score <70; a score of 100 ± 2 s.d. is the range) in at least one domain; and 28% scored between -1 and -2 s.d. in any domain (scores <85-70). Language function was most affected, with 35% of 146 children below average. Improved neurodevelopmental outcomes were noted in female children, term babies, children with normal eye exams and maternal infection later in pregnancy (P = 0.01). We noted resolution of microcephaly with normal neurodevelopment in two of eight children, development of secondary microcephaly in two other children and autism spectrum disorder in three previously healthy children in the second year of life.

Auditory findings associated with Zika virus infection: an integrative review

Introduction

Possible associations between Zika virus infection and hearing loss were observed during the epidemic in the Americas.

Objective

To describe the auditory alterations, pathogenesis and recommendations for follow-up in individuals with prenatal or acquired Zika virus infection.

Methods

Bibliographic research conducted in March/2018–April/2019 at the main available databases. Article selection, data extraction and quality evaluation were carried out by two independent reviewers. Studies containing auditory evaluation of patients with congenital or acquired Zika virus infection; and/or hypotheses or evidences on the pathophysiology of auditory impairment associated with Zika virus; and/or recommendations on screening and follow-up of patients with auditory impairment by Zika virus were included.

Results

A total of 27 articles were selected. Sensorineural and transient hearing loss were reported in six adults with acquired Zika virus infection. Of the 962 studied children, 482 had microcephaly and 145 had diagnostic confirmation of Zika virus; 515 of the 624 children with auditory evaluation performed only screening tests with otoacoustic emissions testing and/or automated click-stimuli auditory brainstem response testing. Studies in prenatally exposed children were very heterogeneous and great variations in the frequency of altered otoacoustic emissions and automated click-stimuli auditory brainstem response occurred across the studies. Altered otoacoustic emissions varied from 0% to 75%, while altered automated click-stimuli auditory brainstem response varied from 0% to 29.2%. Sensorineural, retrocochlear or central origin impairment could not be ruled out. One study with infected mice found no microscopic damage to cochlear hair cells. Studies on the pathogenesis of auditory changes in humans are limited to hypotheses and recommendations still include points of controversy.

Conclusion

The available data are still insufficient to understand the full spectrum of the involvement of the auditory organs by Zika virus, the pathogenesis of this involvement or even to confirm the causal association between auditory involvement and virus infection. The screening and follow-up recommendations still present points of controversy.

Cross-Protection Against Four Serotypes of Dengue Virus in Mice Conferred by a Zika DNA Vaccine

Both Zika virus (ZIKV) and four serotypes of dengue virus (DENV1–4) are antigenically related mosquito-borne flaviviruses that co-circulate in overlapping geographic distributions. The considerable amino acid sequence homology and structural similarities between ZIKV and DENV1–4 may be responsible for the complicated immunological cross-reactivity observed for these viruses. Thus, a successful Zika vaccine needs to not only confer protection from ZIKV infection but must also be safe during secondary exposures with other flavivirus, especially DENVs. In this study, we used a Zika DNA vaccine candidate (pV-ZME) expressing the ZIKV premembrane and envelop proteins to immunize BALB/c mice and evaluated the potential cross-reactive immune responses to DENV1–4. We observed that three doses of the pV-ZME vaccine elicited the production of cross-reactive antibodies, cytokines and CD8⁺ T cell responses and generated cross-protection against DENV1–4. Our results demonstrate a novel approach for design and development of safe Zika and/or dengue vaccines.

Children Born to Mothers with Rash During Zika Virus Epidemic in Brazil: First 18 Months of Life

OBJECTIVE

To better understand the clinical spectrum and course of congenital Zika syndrome (CZS) during the first 18 months of life of children whose mothers had rash during pregnancy.

METHODS

This longitudinal observational study evaluated the clinical progress from birth until 18 months of life of children of mothers who developed rash during or up to 3 months before gestation. Maternal rash occurred from November 2015 to May 2017. The study subjects were divided into three groups: children whose mothers tested positive by RT-qPCR for Zika virus (ZIKV) (Group 1), children whose mothers tested negative by RT-qPCR for ZIKV (Group 2), and children whose mothers did not undergo any testing for ZIKV (Group 3) but tested negative for other congenital infections.

RESULTS

Between April 2016 and July 2018, we studied 108 children: 43 in Group 1, 26 in Group 2 and 39 in Group 3. The majority of children were admitted into the study within 6 months of life. CZS was diagnosed in 26 children, equally distributed in Groups 1 and 3. Of 18 children with microcephaly, 6 were in Group 1 (1 postnatal) and 12 were in Group 3 (5 postnatal). Maternal rash frequency was 10 times higher during the first trimester than in the other trimesters (OR: 10.35; CI 95%: 3.52-30.41). CZS was diagnosed during the follow-up period in 14 (54%) cases. Developmental delays and motor abnormalities occurred in all children and persisted up to 18 months. Epilepsy occurred in 18 (69%) of the cases.

CONCLUSIONS

Infants born of mothers exposed to ZIKV during pregnancy showed progression of developmental, motor and neurologic abnormalities even if they were born asymptomatic. Continued postnatal monitoring of such newborns is necessary to preclude disability-associated complications.

Impact of preexisting dengue immunity on Zika virus emergence in a dengue endemic region

The clinical outcomes associated with Zika virus (ZIKV) in the Americas have been well documented, but other aspects of the pandemic, such as attack rates and risk factors, are poorly understood. We prospectively followed a cohort of 1453 urban residents in Salvador, Brazil, and, using an assay that measured immunoglobulin G3 (IgG3) responses against ZIKV NS1 antigen, we estimated that 73% of individuals were infected during the 2015 outbreak. Attack rates were spatially heterogeneous, varying by a factor of 3 within a community spanning 0.17 square kilometers. Preexisting high antibody titers to dengue virus were associated with reduced risk of ZIKV infection and symptoms. The landscape of ZIKV immunity that now exists may affect the risk for future transmission.