Association between Zika virus and fetopathy: a prospective cohort study in French Guiana

Association of Prenatal Ultrasonographic Findings With Adverse Neonatal Outcomes Among Pregnant Women With Zika Virus Infection in Brazil

IMPORTANCE

Congenital Zika virus infection causes a spectrum of adverse birth outcomes, including severe birth defects of the central nervous system. The association of prenatal ultrasonographic findings with adverse neonatal outcomes, beyond structural anomalies such as microcephaly, has not been described to date.

OBJECTIVE

To determine whether prenatal ultrasonographic examination results are associated with abnormal neonatal outcomes in Zika virus-affected pregnancies.

DESIGN, SETTING, AND PARTICIPANTS

A prospective cohort study conducted at a single regional referral center in Rio de Janeiro, Brazil, from September 1, 2015, to May 31, 2016, among 92 pregnant women diagnosed during pregnancy with Zika virus infection by reverse-transcription polymerase chain reaction, who underwent subsequent prenatal ultrasonographic and neonatal evaluation.

EXPOSURES

Prenatal ultrasonography.

MAIN OUTCOMES AND MEASURES

The primary outcome measure was composite adverse neonatal outcome (perinatal death, abnormal finding on neonatal examination, or abnormal finding on postnatal neuroimaging). Secondary outcomes include association of specific findings with neonatal outcomes.

RESULTS

Of 92 mother-neonate dyads (mean [SD] maternal age, 29.4 [6.3] years), 55 (60%) had normal results and 37 (40%) had abnormal results on prenatal ultrasonographic examinations. The median gestational age at delivery was 38.6 weeks (interquartile range, 37.9-39.3). Of the 45 neonates with composite adverse outcome, 23 (51%) had normal results on prenatal ultrasonography. Eleven pregnant women (12%) had a Zika virus-associated finding that was associated with an abnormal result on neonatal examination (adjusted odds ratio [aOR], 11.6; 95% CI, 1.8-72.8), abnormal result on postnatal neuroimaging (aOR, 6.7; 95% CI, 1.1-38.9), and composite adverse neonatal outcome (aOR, 27.2; 95% CI, 2.5-296.6). Abnormal results on middle cerebral artery Doppler ultrasonography were associated with neonatal examination abnormalities (aOR, 12.8; 95% CI, 2.6-63.2), postnatal neuroimaging abnormalities (aOR, 8.8; 95% CI, 1.7-45.9), and composite adverse neonatal outcome (aOR, 20.5; 95% CI, 3.2-132.6). There were 2 perinatal deaths. Abnormal findings on prenatal ultrasonography had a sensitivity of 48.9% (95% CI, 33.7%-64.2%) and a specificity of 68.1% (95% CI, 52.9%-80.1%) for association with composite adverse neonatal outcomes. For a Zika virus-associated abnormal result on prenatal ultrasonography, the sensitivity was lower (22.2%; 95% CI, 11.2%-37.1%) but the specificity was higher (97.9%; 95% CI, 88.7%-99.9%).

CONCLUSIONS AND RELEVANCE

Abnormal results on prenatal ultrasonography were associated with adverse outcomes in congenital Zika infection. The absence of abnormal findings on prenatal ultrasonography was not associated with a normal neonatal outcome. Comprehensive evaluation is recommended for all neonates with prenatal Zika virus exposure.

Maternal-fetal transmission and adverse perinatal outcomes in pregnant women infected with Zika virus: prospective cohort study in French Guiana

OBJECTIVES

To estimate the rates of maternal-fetal transmission of Zika virus, adverse fetal/neonatal outcomes, and subsequent rates of asymptomatic/symptomatic congenital Zika virus infections up to the first week of life.

DESIGN

Cohort study with prospective data collection and subsequent review of fetal/neonatal outcomes.

SETTINGS

Referral centre for prenatal diagnosis of the French Guiana Western Hospital.

PARTICIPANTS

Pregnant women at any stage of pregnancy with a laboratory confirmed symptomatic or asymptomatic Zika virus infection during the epidemic period in western French Guiana. The cohort enrolled 300 participants and prospectively followed their 305 fetuses/newborns.

MAIN OUTCOME MEASURES

Rate of maternal-fetal transmission of Zika virus (amniotic fluid, fetal and neonatal blood, urine, cerebrospinal fluid, and placentas); clinical, biological, and radiological outcomes (blindly reviewed); and adverse outcomes defined as moderate signs potentially related to congenital Zika syndrome (CZS), severe complications compatible with CZS, or fetal loss. Associations between a laboratory confirmed congenital Zika virus infection and adverse fetal/neonatal outcomes were evaluated.

RESULTS

Maternal-fetal transmission was documented in 26% (76/291) of fetuses/newborns with complete data. Among the Zika virus positive fetuses/newborns, 45% (34/76) presented with no signs/complications at birth, 20% (15/76) with moderate signs potentially related to CZS, 21% (16/76) with severe complications compatible with CZS, and 14% (11/76) with fetal loss. Compared with the Zika virus positive fetuses/neonates, those that were identified as negative for Zika virus (215/291) were less likely to present with severe complications (5%; 10/215) or fetal loss (0.5%; 1/215; relative risk 6.9, 95% confidence interval 3.6 to 13.3). Association between a positive Zika virus test and any adverse fetal/neonatal outcome was also significant (relative risk 4.4, 2.9 to 6.6). The population attributable fraction estimates that a confirmed congenital Zika virus infection contributes to 47% of adverse outcomes and 61% of severe adverse outcomes observed.

CONCLUSION

In cases of a known maternal Zika virus infection, approximately a quarter of fetuses will become congenitally infected, of which a third will have severe complications at birth or fetal loss. The burden of CZS might be lower than initially described in South America and may not differ from other congenital infections.

Animal Models of Zika Virus Infection during Pregnancy

Zika virus (ZIKV) emerged suddenly in the Americas in 2015 and was associated with a widespread outbreak of microcephaly and other severe congenital abnormalities in infants born to mothers infected during pregnancy. Vertical transmission of ZIKV in humans was confirmed when viral RNA was detected in fetal and placental tissues, and this outcome has been recapitulated experimentally in animals. Unlike other flaviviruses, ZIKV is both arthropod- and sexually-transmitted, and has a broad tissue tropism in humans, including multiple tissues of the reproductive tract. The threats posed by ZIKV have prompted the development of multiple in vivo models to better understand the pathogenesis of ZIKV, particularly during pregnancy. Here, we review the progress on animal models of ZIKV infection during pregnancy. These studies have generated a foundation of insights into the biology of ZIKV, and provide a means for evaluating vaccines and therapeutics.

A clinical and histopathological study of malformations observed in fetuses infected by the Zika virus

BACKGROUND

The recent outbreak of Zika virus (ZIKV) infection and the associated increased prevalence of microcephaly in Brazil underline the impact of viral infections on embryo fetal development. The aim of the present study is to provide a detailed clinical and histopathological study of the fetal disruption caused by the ZIKV, with a special focus on the associated neuropathological findings.

METHODS

A detailed feto-placental examination, as well as neuropathological and neurobiological studies were performed on three fetuses collected after pregnancy termination between 22 and 25 weeks of gestation (WG), because brain malformations associated with a maternal and fetal ZIKV infection was diagnosed.

RESULTS

In all three cases, the maternal infection occurred during the first trimester of pregnancy. A small head was observed on the ultrasound examination of the second trimester of pregnancy and led to the diagnosis of ZIKV fetopathy and pregnancy termination. The fetal histopathological examination was unremarkable on the viscera but showed on the testis an interstitial lymphocytic infiltrate. The placenta contained a Hofbauer cells hyperplasia with signs of inflammation. Neuropathological findings included a meningoencephalitis and an ex vacuo hydrocephalus. Immunohistochemical studies showed the presence of T lymphocytic and histiocytic meningitis associated with an abundant cerebral astroglial and macrophagic reaction. In situ hybridization demonstrated, abundant ZIKV particles within the cerebral parenchyma mainly in the ventricular/subventricular zone and in the cortical plate. In addition massive cells death and endoplasmic reticulum damage were present.

CONCLUSION

The present study reports on the clinical and histopathological findings observed in three fetuses infected by the ZIKV. It emphasizes the severity of brain damages and the minimal visceral and placental changes observed upon ZIKV infection. This confirms the selective neurotropism of ZIKV. Finally, it allows us to describe the cascade of multifactorial developmental defects leading to microcephaly.

Congenital Zika virus syndrome…what else? Two case reports of severe combined fetal pathologies

BACKGROUND

Zika virus (ZIKV) has recently emerged as a teratogenic infectious agent associated with severe fetal cerebral anomalies. Other microorganisms (TORCH agents) as well as genetic disorders and toxic agents may lead to similar anomalies. In case of fetal anomalies, the exact etiology might be difficult to establish, especially in ZIKV endemic countries. As the risks associated with maternal infection remain unclear adequate parental counseling is difficult.

CASE PRESENTATION

We present two cases of severe fetal pathologies managed in our multidisciplinary center during the ZIKV outbreak in Martinique, a French Caribbean Island. Both fetuses had congenital ZIKV infection confirmed by RT-PCR. While one case presented with significant cerebral anomalies, the other one presented with hydrops fetalis. A complete analysis revealed that the fetal lesions observed resulted from a combination of ZIKV congenital infection and a genetic disorder (trisomy 18) in case 1 or congenital Parvovirus B19 infection in case 2.

CONCLUSIONS

We highlight the difficulties related to adequate diagnosis in case of suspected ZIKV congenital syndrome. Additional factors may contribute to or cause fetal pathology, even in the presence of a confirmed ZIKV fetal infection. An exact diagnosis is mandatory to draw definitive conclusions. We further emphasize that, similarly to other congenital infections, it is very likely that not all infected fetuses will become symptomatic.

Prevalence of asymptomatic Zika virus infection: a systematic review

Objective

To conduct a systematic review to estimate the prevalence of asymptomatic Zika virus infection in the general population and in specific population groups.

Methods

We searched PubMed®, Embase® and LILACS online databases from inception to 26 January 2018. We included observational epidemiological studies where laboratory testing was used to confirm positive exposure of participants to Zika virus and in which Zika virus symptom status was also recorded. We excluded studies in which having symptoms of Zika virus was a criterion for inclusion. The main outcome assessed was percentage of all Zika virus-positive participants who were asymptomatic. We used a quality-effects approach and the double arcsine transformation for the meta-analysis.

Findings

We assessed 753 studies for inclusion, of which 23 were included in the meta-analysis, totalling 11 305 Zika virus-positive participants. The high degree of heterogeneity in the studies (I² = 99%) suggests that the pooled prevalence of asymptomatic Zika virus-positive participants was probably not a robust estimate. Analysis based on subgroups of the population (general population, returned travellers, blood donors, adults with Guillain–Barré syndrome, pregnant women and babies with microcephaly) was not able to explain the heterogeneity. Funnel and Doi plots showed major asymmetry, suggesting selection bias or true heterogeneity.

Conclusion

Better-quality research is needed, using standardized methods, to determine the true prevalence of asymptomatic Zika virus and whether it varies between populations or over time.

Zika Virus in the Male Reproductive Tract

Arthropod-borne viruses (arboviruses) are resurging across the globe. Zika virus (ZIKV) has caused significant concern in recent years because it can lead to congenital malformations in babies and Guillain-Barré syndrome in adults. Unlike other arboviruses, ZIKV can be sexually transmitted and may persist in the male reproductive tract. There is limited information regarding the impact of ZIKV on male reproductive health and fertility. Understanding the mechanisms that underlie persistent ZIKV infections in men is critical to developing effective vaccines and therapies. Mouse and macaque models have begun to unravel the pathogenesis of ZIKV infection in the male reproductive tract, with the testes and prostate gland implicated as potential reservoirs for persistent ZIKV infection. Here, we summarize current knowledge regarding the pathogenesis of ZIKV in the male reproductive tract, the development of animal models to study ZIKV infection at this site, and prospects for vaccines and therapeutics against persistent ZIKV infection.

Zika virus infection in a pregnant Canadian traveler with congenital fetal malformations noted by ultrasonography at 14-weeks gestation

BACKGROUND

Following emergence of Zika virus in the Americas, a devastating new congenital syndrome has been documented, leading to significant morbidity among Zika-infected fetuses and neonates.

CASE PRESENTATION

A 29-year-old pregnant woman infected with Zika virus at 9-weeks gestation in Trinidad presented with one-month of fever, headache, and myalgia with persistent viremia. Significant fetal abnormalities were identified at 14-week ultrasound, which is the earliest ultrasound to describe a severely affected fetus following Zika virus infection to our knowledge.

CONCLUSIONS

We discuss the implications of prolonged maternal viremia and the spectrum of congenital Zika syndrome detectable by fetal ultrasound.

Clinical assessment and brain findings in a cohort of mothers, fetuses and infants infected with ZIKA virus

BACKGROUND

Congenital Zika virus (ZIKV) infection can be detected in both the presence and absence of microcephaly and manifests as a number of signs and symptoms that are detected clinically and by neuroimaging. However, to date, qualitative and quantitative measures for the purpose of diagnosis and prognosis are limited.

OBJECTIVES

Main objectives of this study conducted on fetuses and infants with confirmed congenital Zika virus infection and detected brain abnormalities were (1) to assess the prevalence of microcephaly and the frequency of the anomalies that include a detailed description based on ultrasound and magnetic resonance imaging in fetuses and ultrasound, magnetic resonance imaging, and computed tomography imaging postnatally, (2) to provide quantitative measures of fetal and infant brain findings by magnetic resonance imaging with the use of volumetric analyses and diffusion-weighted imaging, and (3) to obtain additional information from placental and fetal histopathologic assessments and postnatal clinical evaluations.

STUDY DESIGN

This is a longitudinal cohort study of Zika virus-infected pregnancies from a single institution in Colombia. Clinical and imaging findings of patients with laboratory-confirmed Zika virus infection and fetal brain anomalies were the focus of this study. Patients underwent monthly fetal ultrasound scans, neurosonography, and a fetal magnetic resonance imaging. Postnatally, infant brain assessment was offered by the use of ultrasound imaging, magnetic resonance imaging, and/or computed tomography. Fetal head circumference measurements were compared with different reference ranges with <2 or <3 standard deviations below the mean for the diagnosis of microcephaly. Fetal and infant magnetic resonance imaging images were processed to obtain a quantitative brain volumetric assessment. Diffusion weighted imaging sequences were processed to assess brain microstructure. Anthropometric, neurologic, auditory, and visual assessments were performed postnatally. Histopathologic assessment was included if patients opted for pregnancy termination.

RESULTS

All women (n=214) had been referred for Zika virus symptoms during pregnancy that affected themselves or their partners or if fetal anomalies that are compatible with congenital Zika virus syndrome were detected. A total of 12 pregnant patients with laboratory confirmation of Zika virus infection were diagnosed with fetal brain malformations. Most common findings that were assessed by prenatal and postnatal imaging were brain volume loss (92%), calcifications (92%), callosal anomalies (100%), cortical malformations (89%), and ventriculomegaly (92%). Results from fetal brain volumetric assessment by magnetic resonance imaging showed that 1 of the most common findings associated with microcephaly was reduced supratentorial brain parenchyma and increased subarachnoid cerebrospinal fluid. Diffusion weighted imaging analyses of apparent diffusion coefficient values showed microstructural changes. Microcephaly was present in 33.3-58.3% of the cases at referral and was present at delivery in 55.6-77.8% of cases. At birth, most of the affected neonates (55.6-77.8%) had head circumference measurements >3 standard deviations below the mean. Postnatal imaging studies confirmed brain malformations that were detected prenatally. Auditory screening results were normal in 2 cases that were assessed. Visual screening showed different anomalies in 2 of the 3 cases that were examined. Pathologic results that were obtained from 2 of the 3 cases who opted for termination showed similar signs of abnormalities in the central nervous system and placental analyses, including brain microcalcifications.

CONCLUSION

Congenital microcephaly is not an optimal screening method for congenital Zika virus syndrome, because it may not accompany other evident and preceding brain findings; microcephaly could be an endpoint of the disease that results from progressive changes that are related to brain volume loss. Long-term studies are needed to understand the clinical and developmental relevance of these findings.

Pregnancy Outcomes after ZIKV Infection in French Territories in the Americas

BACKGROUND

The risk of congenital neurologic defects related to Zika virus (ZIKV) infection has ranged from 6 to 42% in various reports. The aim of this study was to estimate this risk among pregnant women with symptomatic ZIKV infection in French territories in the Americas.

METHODS

From March 2016 through November 2016, we enrolled in this prospective cohort study pregnant women with symptomatic ZIKV infection that was confirmed by polymerase-chain-reaction (PCR) assay. The analysis included all data collected up to April 27, 2017, the date of the last delivery in the cohort.

RESULTS

Among the 555 fetuses and infants in the 546 pregnancies included in the analysis, 28 (5.0%) were not carried to term or were stillborn, and 527 were born alive. Neurologic and ocular defects possibly associated with ZIKV infection were seen in 39 fetuses and infants (7.0%; 95% confidence interval, 5.0 to 9.5); of these, 10 were not carried to term because of termination of pregnancy for medical reasons, 1 was stillborn, and 28 were live-born. Microcephaly (defined as head circumference more than 2 SD below the mean for sex and gestational age) was detected in 32 fetuses and infants (5.8%), of whom 9 (1.6%) had severe microcephaly (more than 3 SD below the mean). Neurologic and ocular defects were more common when ZIKV infection occurred during the first trimester (24 of 189 fetuses and infants [12.7%]) than when it occurred during the second trimester (9 of 252 [3.6%]) or third trimester (6 of 114 [5.3%]) (P=0.001).

CONCLUSIONS

Among pregnant women with symptomatic, PCR-confirmed ZIKV infection, birth defects possibly associated with ZIKV infection were present in 7% of fetuses and infants. Defects occurred more frequently in fetuses and infants whose mothers had been infected early in pregnancy. Longer-term follow-up of infants is required to assess any manifestations not detected at birth. (Funded by the French Ministry of Health and others; ClinicalTrials.gov number, NCT02916732 .).

Zika virus and pregnancy in Brazil: What happened?

The recent epidemic of Zika virus (ZIKV) infection in Central and South America is one of the most serious global public health emergencies since the Ebola outbreak in West Africa. In Brazil, especially in the north, northeast, and southeast parts of the country, the ZIKV outbreak is a cause of concern for pregnant women because ZIKV intrauterine infection has been found to be associated with multiple brain malformations and microcephaly. In Brazil, the number of newborns with confirmed microcephaly per year recorded during the ZIKV outbreak, has been approximately 15 times greater than previously reported. Considering that the infection is self-limiting and symptomatic, it is usually diagnosed at the time of routine prenatal scan, especially in the third trimester. In other cases, the disease is detected after childbirth through neuroimaging. This study provides an insight into the history and evolution of ZIKV in Brazil, including current knowledge concerning the transmission, diagnosis, and pathogenesis of the infection. In addition, this review describes the pre- and postnatal neuroimaging findings obtained using ultrasound, magnetic resonance imaging, and computed tomography.

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

Background. The Zika virus (ZIKV) outbreak in the Americas has caused international concern due to neurological sequelae linked to the infection, such as microcephaly and Guillain-Barré syndrome (GBS). The World Health Organization stated that there is “sufficient evidence to conclude that Zika virus is a cause of congenital abnormalities and is a trigger of GBS”. This conclusion was based on a systematic review of the evidence published until 30.05.2016. Since then, the body of evidence has grown substantially, leading to this update of that systematic review with new evidence published from 30.05.2016 – 18.01.2017, update 1.

Methods. We review evidence on the causal link between ZIKV infection and adverse congenital outcomes and the causal link between ZIKV infection and GBS or immune-mediated thrombocytopaenia purpura. We also describe the transition of the review into a living systematic review, a review that is continually updated.

Results. Between 30.05.2016 and 18.01.2017, we identified 2413 publications, of which 101 publications were included. The evidence added in this update confirms the conclusion of a causal association between ZIKV and adverse congenital outcomes. New findings expand the evidence base in the dimensions of biological plausibility, strength of association, animal experiments and specificity. For GBS, the body of evidence has grown during the search period for update 1, but only for dimensions that were already populated in the previous version. There is still a limited understanding of the biological pathways that potentially cause the occurrence of autoimmune disease following ZIKV infection.

Conclusions. This systematic review confirms previous conclusions that ZIKV is a cause of congenital abnormalities, including microcephaly, and is a trigger of GBS. The transition to living systematic review techniques and methodology provides a proof of concept for the use of these methods to synthesise evidence about an emerging pathogen such as ZIKV.

Cerebral injuries associated with Zika virus in utero exposure in children without birth defects in French Guiana: Case report

RATIONALE

A major epidemic of Zika virus (ZIKV) infection occurred in French Guiana and West Indies. French national epidemiological surveillance estimated that 1650 pregnant women contracted the ZIKV during epidemic period from January 2016 to October 2016 in French Guiana.

PATIENT CONCERNS

ZIKV infection during pregnancy is a cause of microcephaly and birth defects.

DIAGNOSES

In this report, we describe 2 children with proven in utero ZIKV exposure. Their mothers were both symptomatic and ZIKV infection occurred early in pregnancy. Ultrasonography monitoring in utero did not show any abnormality for both patient. They were born at full-term, healthy, without any birth defects and no sign of congenital ZIKV infection.

INTERVENTIONS

ZIKV was neither found on placenta fragments nor children blood and urine at birth. Their neurodevelopment outcomes in early-life fitted the expectations. As recommended in national guidelines, we performed cerebral MRIs at 2 months old, showing severe brain abnormalities, especially of white matter areas. After a large screening, we did not find any differential diagnosis for their brain lesions.

OUTCOMES

We concluded it was due to their in utero ZIKV exposure.

LESSONS

In this report, pathogenicity of ZIKV may involve mother's immunological response or metabolic disorder during the infection.

High Zika Virus Seroprevalence in Salvador, Northeastern Brazil Limits the Potential for Further Outbreaks

During 2015 to 2016, Brazil reported more Zika virus (ZIKV) cases than any other country, yet population exposure remains unknown. Serological studies of ZIKV are hampered by cross-reactive immune responses against heterologous viruses. We conducted serosurveys for ZIKV, dengue virus (DENV), and Chikungunya virus (CHIKV) in 633 individuals prospectively sampled during 2015 to 2016, including microcephaly and non-microcephaly pregnancies, HIV-infected patients, tuberculosis patients, and university staff in Salvador in northeastern Brazil using enzyme-linked immunosorbent assays (ELISAs) and plaque reduction neutralization tests. Sera sampled retrospectively during 2013 to 2015 from 277 HIV-infected patients were used to assess the spread of ZIKV over time. Individuals were georeferenced, and sociodemographic indicators were compared between ZIKV-positive and -negative areas and areas with and without microcephaly cases. Epidemiological key parameters were modeled in a Bayesian framework. ZIKV seroprevalence increased rapidly during 2015 to 2016, reaching 63.3% by 2016 (95% confidence interval [CI], 59.4 to 66.8%), comparable to the seroprevalence of DENV (75.7%; CI, 69.4 to 81.1%) and higher than that of CHIKV (7.4%; CI, 5.6 to 9.8%). Of 19 microcephaly pregnancies, 94.7% showed ZIKV IgG antibodies, compared to 69.3% of 257 non-microcephaly pregnancies (P = 0.017). Analyses of sociodemographic data revealed a higher ZIKV burden in low socioeconomic status (SES) areas. High seroprevalence, combined with case data dynamics allowed estimates of the basic reproduction number R0 of 2.1 (CI, 1.8 to 2.5) at the onset of the outbreak and an effective reproductive number Reff of <1 in subsequent years. Our data corroborate ZIKV-associated congenital disease and an association of low SES and ZIKV infection and suggest that population immunity caused cessation of the outbreak. Similar studies from other areas will be required to determine the fate of the American ZIKV outbreak.IMPORTANCE The ongoing American Zika virus (ZIKV) outbreak involves millions of cases and has a major impact on maternal and child health. Knowledge of infection rates is crucial to project future epidemic patterns and determine the absolute risk of microcephaly upon maternal ZIKV infection during pregnancy. For unknown reasons, the vast majority of ZIKV-associated microcephaly cases are concentrated in northeastern Brazil. We analyzed different subpopulations from Salvador, a Brazilian metropolis representing one of the most affected areas during the American ZIKV outbreak. We demonstrate rapid spread of ZIKV in Salvador, Brazil, and infection rates exceeding 60%. We provide evidence for the link between ZIKV and microcephaly, report that ZIKV predominantly affects geographic areas with low socioeconomic status, and show that population immunity likely caused cessation of the outbreak. Our results enable stakeholders to identify target populations for vaccination and for trials on vaccine efficacy and allow refocusing of research efforts and intervention strategies.

Impact of Zika virus for infertility specialists: current literature, guidelines, and resources

In the past 2 years, Zika virus has emerged from obscurity onto the world stage-traversing and transcending clinical specialties, basic science disciplines, and public health efforts. The spread of Zika virus has serious implications for the specialty of reproductive endocrinology and infertility. Our patients, practices, and labs-worldwide and specifically in the USA-have been impacted by this teratogenic, sexually transmitted, largely asymptomatic virus. While the World Health Organization's Public Emergency of International Concern designation has lapsed as major epidemics have subsided and understanding of risks is in part clarified, the acute and long-term threat to pregnant patients is not over. The risk of wider spread in the USA is not insignificant, the subtler and long-ranging consequences beyond microcephaly are not fully known, large geographic areas of risk still contain naïve populations, and whether Zika will continue to be an intermittent risk in endemic areas is uncertain. Staying up to date with the burgeoning research on Zika virus is an important objective for the infertility specialist. Here, we review in detail the most relevant recent developments, discuss applicable guidelines, and propose strategies for contributing to a reduction in the risk and burden of Zika virus.

Microcephaly Prevalence in Infants Born to Zika Virus-Infected Women: A Systematic Review and Meta-Analysis

Zika virus is an emergent flavivirus transmitted by Aedes genus mosquitoes that recently reached the Americas and was soon implicated in an increase of microcephaly incidence. The objective of the present study is to systematically review the published data and perform a meta-analysis to estimate the prevalence of microcephaly in babies born to Zika virus-infected women during pregnancy. We searched PubMed and Cochrane databases, included cohort studies, and excluded case reports and case series publications. We extracted sample sizes and the number of microcephaly cases from eight studies, which permitted a calculation of prevalence rates that are pooled in a random-effects model meta-analysis. We estimated the prevalence of microcephaly of 2.3% (95% CI = 1.0–5.3%) among all pregnancies. Limitations include mixed samples of women infected at different pregnancy times, since it is known that infection at the first trimester is associated with higher risk to congenital anomalies. The estimates are deceptively low, given the devastating impact the infection causes over children and their families. We hope our study contributes to public health knowledge to fight Zika virus epidemics to protect mothers and their newborns.

Mosquito-borne and sexual transmission of Zika virus: Recent developments and future directions

Zika virus (ZIKV; Genus Flavivirus, Family Flaviviridae) has recently emerged in Asia and the Americas to cause large outbreaks of human disease. The outbreak has been characterized by high attack rates, birth defects in infants and severe neurological complications in adults. ZIKV is transmitted to humans by Aedes mosquitoes, but recent evidence implicates sexual transmission as playing an important role as well. This review highlights the transmission of ZIKV in humans, with a focus on both mosquito and sexually-transmitted routes and their outcomes. We also discuss critical directions for future research.

Serial Head and Brain Imaging of 17 Fetuses With Confirmed Zika Virus Infection in Colombia, South America

OBJECTIVE

To evaluate fetal ultrasound and magnetic resonance imaging findings among a series of pregnant women with confirmed Zika virus infection to evaluate the signs of congenital Zika syndrome with respect to timing of infection.

METHODS

We conducted a retrospective case series of pregnant women referred to two perinatal clinics in Barranquilla and Ibagué, Colombia, who had findings consistent with congenital Zika syndrome and Zika virus infection confirmed in maternal, fetal, or neonatal samples. Serial ultrasound measurements, fetal magnetic resonance imaging results, laboratory results, and perinatal outcomes were evaluated.

RESULTS

We describe 17 cases of confirmed prenatal maternal Zika virus infection with adverse fetal outcomes. Among the 14 symptomatic women, the median gestational age for maternal Zika virus symptoms was 10 weeks (range 7-14 weeks of gestation). The median time between Zika virus symptom onset and microcephaly (head circumference less than 3 standard deviations below the mean) was 18 weeks (range 15-24 weeks). The earliest fetal head circumference measurement consistent with microcephaly diagnosis was at 24 weeks of gestation. The earliest sign of congenital Zika syndrome was talipes equinovarus, which in two patients was noted first at 19 weeks of gestation. Common findings on fetal magnetic resonance imaging were microcephaly, ventriculomegaly, polymicrogyria, and calcifications.

CONCLUSION

Our analysis suggests a period of at least 15 weeks between maternal Zika virus infection in pregnancy and development of microcephaly and highlights the importance of serial and detailed neuroimaging.

Ultrasound imaging for identification of cerebral damage in congenital Zika virus syndrome: a case series

BACKGROUND

Zika virus is a novel teratogenic agent associated with cerebral anomalies. Because of the challenges associated with assessment of antenatal diagnosis and prognosis in fetuses, screening for other congenital infections mostly relies on ultrasound. We aimed to assess whether a similar approach might be adequate for Zika virus congenital syndrome provided that early markers of infection and adequate timing for screening are established.

METHODS

For this case series we reviewed all pregnant women who had a laboratory-confirmed Zika virus infection in their first trimester or early second trimester and abnormal fetal ultrasound findings who were managed at the Pluridisciplinary Center for Prenatal Diagnosis of Martinique during the Zika virus epidemic (Jan 1, 2016, to Nov 10, 2016) in Martinique, a French Caribbean island. Ultrasound imaging was done with GE Healthcare Voluson E10 and E8 machines with abdominal and vaginal probes.

FINDINGS

We analysed 14 cases of pregnant women with confirmed Zika virus infection and fetal abnormalities of the brain, and 31 ultrasound imaging results. Between 16 and 20 weeks of gestation, four (33%) of 12 fetuses had an abnormal ultrasound examination. Anomalies were detected in nine (90%) of the ten fetuses from whom ultrasound images were obtained between 20 and 24 weeks of gestation. All five remaining fetuses at 24-28 weeks of gestation, and all four after 28 weeks, had severe anomalies. Major anomalies identified were ventriculomegaly (12 fetuses, 86%), cortical atrophy (11, 79%), calcifications (ten, 71%; particularly located at the corticosubcortical junction), and anomalies of the corpus callosum (ten, 71%). Prenatal assessment of head circumference measurement by imaging was not an effective screening tool for congenital Zika virus infection, with microcephaly only identified in nine (64%) fetuses.

INTERPRETATION

Ultrasound monitoring appears to be a good screening strategy to monitor Zika virus-exposed pregnancies. Public health efforts should focus on scanning at 22-26 weeks of gestation. Identification of ventriculomegaly, cortical atrophy, calcifications, and anomalies of the corpus callosum should prompt laboratory screening for Zika virus.

FUNDING

None.