Zika virus infection in French Polynesia

Laboratory Evaluation of Infants with Possible Congenital Zika Virus Infection

Our understanding of the effects of maternal Zika virus infection on the newborn continues to evolve. First discovered in 1947 in the Zika Forest in Uganda, the world became more aware of the virus in 2015, with reports of hundreds of cases of microcephaly in Brazilian newborns whose mothers reported symptoms related to Zika viral infection during pregnancy. This article reviews the current guidelines for laboratory evaluation of newborns with possible congenital Zika virus infection.

Does Zika Virus Cause Microcephaly - Applying the Bradford Hill Viewpoints

INTRODUCTION

Zika virus has been documented since 1952, but been associated with mild, self-limiting disease. Zika virus is classified as an arbovirus from a family of Flaviviridae and primarily spread by Aedes Aegypti mosquitos. However, in a large outbreak in Brazil in 2015, Zika virus has been associated with microcephaly.

METHODS

In this review we applied the Bradford-Hill viewpoints  to investigate the association between Zika virus and microcephaly. We examined historical studies, available data and also compared historical rates of microcephaly prior to the Zika virus outbreak. The available evidence was reviewed against the Bradford Hill viewpoints.

RESULTS

All  the nine criteria were met to varying degrees: strength of association, consistency of the association, specificity, temporality, plausibility, coherence, experimental evidence, biological gradient and analogy. Conclusion: Using the Bradford Hill Viewpoints as an evaluation framework for causation is highly suggestive that the association between Zika virus and microcephaly is causal. Further studies using animal models on the viewpoints which were not as strongly fulfilled would be helpful.

Zika Virus Disease and Associated Neurologic Complications

PURPOSE OF REVIEW

The purpose of this article is to review what is currently known about Zika virus (ZIKV) disease and associated neurologic complications.

RECENT FINDINGS

ZIKV is a mosquito-borne or sexually transmitted flavivirus rapidly spreading throughout the Americas. While ZIKV infection is usually asymptomatic, it may cause a non-specific illness with fever, rash, myalgia, headache, and/or non-purulent conjunctivitis. Additionally, ZIKV has been associated with a number of neurologic complications including microcephaly and other birth defects, Guillain-Barré syndrome, meningoencephalitis, myelitis, and various ophthalmologic abnormalities. Treatment for ZIKV disease is supportive. Those in ZIKV endemic areas should protect themselves from mosquito bites by wearing insect repellent, wearing long-sleeved shirts and pants when outdoors, and/or using air conditioning or window screens when indoors. Furthermore, unprotected sexual intercourse should be temporarily avoided by those who recently traveled to endemic areas. Suspected ZIKV disease cases should be reported to local, state, or territorial health departments.

Dengue and Zika viruses: lessons learned from the similarities between these Aedes mosquito-vectored arboviruses

The currently spreading arbovirus epidemic is having a severe impact on human health worldwide. The two most common flaviviruses, dengue virus (DENV) and Zika virus (ZIKV), are transmitted through the same viral vector, Aedes spp. mosquitoes. Since the discovery of DENV in 1943, this virus has been reported to cause around 390 million human infections per year, approximately 500,000 of which require hospitalization and over 20,000 of which are lethal. The present DENV epidemic is primarily concentrated in Southeast Asia. ZIKV, which was discovered in 1952, is another important arthropod-borne flavivirus. The neurotropic role of ZIKV has been reported in infected newborns with microcephaly and in adults with Guillain-Barre syndrome. Despite DENV and ZIKV sharing the same viral vector, their complex pathogenic natures are poorly understood, and the infections they cause do not have specific treatments or effective vaccines. Therefore, this review will describe what is currently known about the clinical characteristics, pathogenesis mechanisms, and transmission of these two viruses. Better understanding of the interrelationships between DENV and ZIKV will provide a useful perspective for developing an effective strategy for controlling both viruses in the future.

Zika Virus Disease

The Zika virus is an arbovirus belonging to the virus family Flaviviridae. The virus was isolated in 1947 from a rhesus monkey in the Zika Forest of Uganda. The virus causes sporadic mild human infections in Africa and later in Asia. However, by 2007 a major shift in its infection pattern was noticed and thousands of human infections were reported in the State of Yap and Federated States of Micronesia. In the last 3 years, major outbreaks have continued to occur and the virus has spread to several Pacific and American countries. These outbreaks were mostly asymptomatic; however, there were more severe clinical signs associated with the infections. Those signs included microcephaly and Guillain-Barre syndrome. It is believed that various species of mosquitoes can biologically transmit the virus. However, Aedes aegypti is most widely associated with the Zika virus. Recently, new modes of virus transmission have been reported, including mother-to-fetus, sexual, blood transfusion, animal bites, laboratory exposure and breast milk. Differential diagnosis is very important as some other arboviruses such as yellow fever virus, West Nile virus, dengue virus, and chikungunya virus have similar clinical manifestations to the Zika virus infection as well as relating serologically to some of these viruses. Established laboratory diagnostic tests to detect the Zika virus are limited, with reverse transcription polymerase chain reaction being the most widely used test. Taking into consideration the quickness of the spread of infection, size of the infected population and change of the infection severity pattern, the Zika virus infection merits collective efforts on all levels to prevent and control the disease. Limited research work and data, concurrent infection with other arboviruses, involvement of biological vectors, mass crowd events, human and trade movements and lack of vaccines are some of the challenges that we face in our efforts to prevent and control the Zika virus infection.

Zika Virus Infection as a Cause of Congenital Brain Abnormalities and Guillain-Barré Syndrome: Systematic Review

BACKGROUND

The World Health Organization (WHO) stated in March 2016 that there was scientific consensus that the mosquito-borne Zika virus was a cause of the neurological disorder Guillain-Barré syndrome (GBS) and of microcephaly and other congenital brain abnormalities based on rapid evidence assessments. Decisions about causality require systematic assessment to guide public health actions. The objectives of this study were to update and reassess the evidence for causality through a rapid and systematic review about links between Zika virus infection and (a) congenital brain abnormalities, including microcephaly, in the foetuses and offspring of pregnant women and (b) GBS in any population, and to describe the process and outcomes of an expert assessment of the evidence about causality.

METHODS AND FINDINGS

The study had three linked components. First, in February 2016, we developed a causality framework that defined questions about the relationship between Zika virus infection and each of the two clinical outcomes in ten dimensions: temporality, biological plausibility, strength of association, alternative explanations, cessation, dose-response relationship, animal experiments, analogy, specificity, and consistency. Second, we did a systematic review (protocol number CRD42016036693). We searched multiple online sources up to May 30, 2016 to find studies that directly addressed either outcome and any causality dimension, used methods to expedite study selection, data extraction, and quality assessment, and summarised evidence descriptively. Third, WHO convened a multidisciplinary panel of experts who assessed the review findings and reached consensus statements to update the WHO position on causality. We found 1,091 unique items up to May 30, 2016. For congenital brain abnormalities, including microcephaly, we included 72 items; for eight of ten causality dimensions (all except dose-response relationship and specificity), we found that more than half the relevant studies supported a causal association with Zika virus infection. For GBS, we included 36 items, of which more than half the relevant studies supported a causal association in seven of ten dimensions (all except dose-response relationship, specificity, and animal experimental evidence). Articles identified nonsystematically from May 30 to July 29, 2016 strengthened the review findings. The expert panel concluded that (a) the most likely explanation of available evidence from outbreaks of Zika virus infection and clusters of microcephaly is that Zika virus infection during pregnancy is a cause of congenital brain abnormalities including microcephaly, and (b) the most likely explanation of available evidence from outbreaks of Zika virus infection and GBS is that Zika virus infection is a trigger of GBS. The expert panel recognised that Zika virus alone may not be sufficient to cause either congenital brain abnormalities or GBS but agreed that the evidence was sufficient to recommend increased public health measures. Weaknesses are the limited assessment of the role of dengue virus and other possible cofactors, the small number of comparative epidemiological studies, and the difficulty in keeping the review up to date with the pace of publication of new research.

CONCLUSIONS

Rapid and systematic reviews with frequent updating and open dissemination are now needed both for appraisal of the evidence about Zika virus infection and for the next public health threats that will emerge. This systematic review found sufficient evidence to say that Zika virus is a cause of congenital abnormalities and is a trigger of GBS.

Zika virus from a Southeast Asian perspective

Phylogenic evidence suggests that the strain of Zika virus causing an unprecedented outbreak of disease in the Americas had its origin in Southeast Asia, where reports of isolated cases of Zika virus infection have occurred since 2010. Why there has been no large outbreak of Zika infection in Southeast Asia remains unclear and whether such an outbreak will occur in the future is a question of significant concern. This review looks at Zika virus from a Southeast Asian perspective and highlights some of the possible scenarios with regards to Zika virus in this part of the world as well as highlighting some of the research questions that need to be urgently addressed.

Zika virus infection induces mitosis abnormalities and apoptotic cell death of human neural progenitor cells

Zika virus (ZIKV) infection has been associated with severe complications both in the developing and adult nervous system. To investigate the deleterious effects of ZIKV infection, we used human neural progenitor cells (NPC), derived from induced pluripotent stem cells (iPSC). We found that NPC are highly susceptible to ZIKV and the infection results in cell death. ZIKV infection led to a marked reduction in cell proliferation, ultrastructural alterations and induction of autophagy. Induction of apoptosis of Sox2⁺ cells was demonstrated by activation of caspases 3/7, 8 and 9, and by ultrastructural and flow cytometry analyses. ZIKV-induced death of Sox2⁺ cells was prevented by incubation with the pan-caspase inhibitor, Z-VAD-FMK. By confocal microscopy analysis we found an increased number of cells with supernumerary centrosomes. Live imaging showed a significant increase in mitosis abnormalities, including multipolar spindle, chromosome laggards, micronuclei and death of progeny after cell division. FISH analysis for chromosomes 12 and 17 showed increased frequency of aneuploidy, such as monosomy, trisomy and polyploidy. Our study reinforces the link between ZIKV and abnormalities in the developing human brain, including microcephaly.

One year after the Zika virus outbreak in Brazil: from hypotheses to evidence

Zika virusis an arbovirus of the Flaviviridae family with two major strains, an Asian and an African strain. The main vectors involved in the transmission of Zika virus are the Aedes aegypti and Aedes albopictus mosquitoes. Despite its identification, discovered in 1947 in the Zika forest in Uganda, only isolated and sporadic occurrences of human infection were reported within a largely asymptomatic proportion of individuals. The first reported outbreak occurred in 2007 in the Yap Island, which belongs to the Federated States of Micronesia in the Pacific Ocean, and in French Polynesia, where high attack rates occurred and the first cases of associated Guillain-Barré syndrome were reported. From November 2014 to early 2015, the Northeast states of Brazil reported the first outbreaks of Zika virus infection, with laboratory confirmation of Zika virus circulation in April 2015. In the second quarter of 2015, the association between Zika virus infection and neurological symptoms was confirmed in adults. Moreover, in October 2015 a novel suspicion was raised based on clinical and epidemiological observations: that an association between Zika virus infection and neonatal microcephaly may exist. A year after the first reports on Zika virus in Brazil, many hypotheses and much evidence on the patterns of involvement of the disease and its complications have been produced, both in this country and others; other hypotheses still need to be clarified. This review is a synthesis of a new chapter in the history of medicine; it outlines the main results produced.

Association between Zika virus infection and microcephaly in Brazil, January to May, 2016: preliminary report of a case-control study

BACKGROUND

The microcephaly epidemic, which started in Brazil in 2015, was declared a Public Health Emergency of International Concern by WHO in 2016. We report the preliminary results of a case-control study investigating the association between microcephaly and Zika virus infection during pregnancy.

METHODS

We did this case-control study in eight public hospitals in Recife, Brazil. Cases were neonates with microcephaly. Two controls (neonates without microcephaly), matched by expected date of delivery and area of residence, were selected for each case. Serum samples of cases and controls and cerebrospinal fluid samples of cases were tested for Zika virus-specific IgM and by quantitative RT-PCR. Laboratory-confirmed Zika virus infection during pregnancy was defined as detection of Zika virus-specific IgM or a positive RT-PCR result in neonates. Maternal serum samples were tested by plaque reduction neutralisation assay for Zika virus and dengue virus. We estimated crude odds ratios (ORs) and 95% CIs using a median unbiased estimator for binary data in an unconditional logistic regression model. We estimated ORs separately for cases with and without radiological evidence of brain abnormalities.

FINDINGS

Between Jan 15, 2016, and May 2, 2016, we prospectively recruited 32 cases and 62 controls. 24 (80%) of 30 mothers of cases had Zika virus infection compared with 39 (64%) of 61 mothers of controls (p=0·12). 13 (41%) of 32 cases and none of 62 controls had laboratory-confirmed Zika virus infection; crude overall OR 55·5 (95% CI 8·6-∞); OR 113·3 (95% CI 14·5-∞) for seven cases with brain abnormalities; and OR 24·7 (95% CI 2·9-∞) for four cases without brain abnormalities.

INTERPRETATION

Our data suggest that the microcephaly epidemic is a result of congenital Zika virus infection. We await further data from this ongoing study to assess other potential risk factors and to confirm the strength of association in a larger sample size.

FUNDING

Brazilian Ministry of Health, Pan American Health Organization, and Enhancing Research Activity in Epidemic Situations.

The inevitable colonisation of Singapore by Zika virus

Singapore is endemic for Dengue virus, with approximately 10,000 to 20,000 annual cases reported in recent years. In 2012, Chikungunya was introduced, although the numbers of cases reported is much fewer. The current Zika virus pandemic originating in Brazil represents a threat to all regions with Aedes mosquitoes, particularly those well connected by travellers. In this respect, it was felt inevitable that Singapore would eventually realise its third endemic flavivirus. In late August 2016, a primary care practitioner observed a cluster of geographically linked patients attending with fever and rash. This resulted in the first identification of locally transmitted Zika in Singapore on August 27, 2016. This prompted a robust response in an attempt to stop further spread, which continued for approximately 10 days until a large number of laboratory-confirmed cases were found as a result of active case finding. Surprisingly, the strain was later identified to be of Asian lineage and distinct from that originating in the Americas, prompting speculation over the epidemiology of this under recognised virus in Asia.

Neurological manifestations of Zika virus infection

Zika virus (ZIKV) is a flavivirus (Flaviviridae family) transmitted mainly by Aedes mosquitoes. The virus was restricted to the African continent until its spread to south-east Asia in the 1980's, the Micronesia in 2007, the French Polynesia in 2013 and, more recently in the Americas in 2015, where, up to date, the World Health Organization (WHO) has estimated about 3-4 million total cases of ZIKV infection. During outbreaks in the French Polynesia and Brazil in 2013 and 2015, respectively, national health authorities reported potential neurological complications of ZIKV disease, chiefly an upsurge in Guillain-Barré syndrome, which coincided with ZIKV outbreaks. On the other hand, the emergence of ZIKV in Brazil has been associated with a striking increase in the number of reported cases of microcephaly in fetus and newborns, twenty times higher than in that reported in previous years. While investigations are currently assessing whether there is an actual association between neurological complications and ZIKV infections, the evidence was enough worrisome for WHO to declare a public health emergency of international concern. Here we present an updated review addressing what is currently known about the possible association between ZIKV infection and the development of severe neurological disorders.

Zika mosquito vectors: the jury is still out

After a 40-year hiatus, the International Congress of Entomology (ICE 2016) convened in Orlando, Florida (September 25-30, 2016). One of the symposia at ICE 2016, the Zika Symposium, covered multiple aspects of the Zika epidemic, including epidemiology, sexual transmission, genetic tools for reducing transmission, and particularly vector competence. While there was a consensus among participants that the yellow fever mosquito, Aedes aegypti, is a vector of the Zika virus, there is growing evidence indicating that the range of mosquito vectors might be wider than anticipated. In particular, three independent groups from Canada, China, and Brazil presented and discussed laboratory and field data strongly suggesting that the southern house mosquito, Culex quinquefasciatus, also known as the common mosquito, is highly likely to be a vector in certain environments.

Available Evidence of Association between Zika Virus and Microcephaly

OBJECTIVE

To clarify the possible association between the Zika virus (ZIKV) and microcephaly and understand where we are in terms of research and the debate on the causation between mild maternal clinical features and severe fetal microcephaly.

DATA SOURCES

We did a comprehensive literature review with the keywords "zika" and/or "microcephaly" from inception to May 27, 2016, with PubMed.

STUDY SELECTION

Studies were included and analyzed if they met all of the following criteria: "probable or confirmed infant microcephaly" and "probable or confirmed ZIKV infection among mothers or infants".

RESULTS

We emphasize the diagnosis of ZIKV infection, including maternal clinical manifestations, maternal and fetal laboratory confirmation, and possible autopsy if need. Other confounders that may lead to microcephaly should be excluded from the study. We presented the results from clinical manifestations of ZIKV infection, testing methods evolving but the mechanism of microcephaly uncertain, flexible definition challenging the diagnosis of microcephaly, and limited causal reference on pregnant women. We made analog comparison of severe acute respiratory syndrome and chikungunya virus in terms of DNA mutation and global movement to provide further research recommendation. The chance of catch-up growth may decrease the number of pervious "diagnosed" microcephaly.

CONCLUSIONS

There are some evidence available through mice models and direct isolation of ZIKV in affected pregnancies on kindly causal relationship but not convincible enough. We analyzed and presented the weakness or limitation of published reports with the desire to shed light to further study directions.

Zika Virus: Pathology From the Pandemic

CONTEXT

-As the number of Zika virus (ZIKV) infections continues to grow, so, too, does the spectrum of recognized clinical disease, in both adult and congenital infections. Defining the tissue pathology associated with the various disease manifestations provides insight into pathogenesis and diagnosis, and potentially future prevention and treatment, of ZIKV infections.

OBJECTIVE

-To summarize the syndromes and pathology associated with ZIKV infection, the implications of pathologic findings in the pathogenesis of ZIKV disease, and the use of pathology specimens for diagnosis of ZIKV infection.

DATA SOURCES

-The major sources of information for this review were published articles obtained from PubMed and pathologic findings from cases submitted to the Infectious Diseases Pathology Branch at the Centers for Disease Control and Prevention.

CONCLUSIONS

-Pathologic findings associated with ZIKV infection are characteristic but not specific. In congenital Zika syndrome, tissue pathology is due to direct viral infection of neural structures, whereas in Guillain-Barré syndrome, pathology is likely due to a postviral, aberrant host-directed immune response. Both fetal and placental pathology specimens are useful for ZIKV diagnosis by molecular and immunohistochemical assays; however, the implications of ZIKV detection in placentas from second- and third-trimester normal live births are unclear, as the potential postnatal effects of late gestational exposure remain to be seen.

Pathology of congenital Zika syndrome in Brazil: a case series

BACKGROUND

Zika virus is an arthropod-borne virus that is a member of the family Flaviviridae transmitted mainly by mosquitoes of the genus Aedes. Although usually asymptomatic, infection can result in a mild and self-limiting illness characterised by fever, rash, arthralgia, and conjunctivitis. An increase in the number of children born with microcephaly was noted in 2015 in regions of Brazil with high transmission of Zika virus. More recently, evidence has been accumulating supporting a link between Zika virus and microcephaly. Here, we describe findings from three fatal cases and two spontaneous abortions associated with Zika virus infection.

METHODS

In this case series, formalin-fixed paraffin-embedded tissue samples from five cases, including two newborn babies with microcephaly and severe arthrogryposis who died shortly after birth, one 2-month-old baby, and two placentas from spontaneous abortions, from Brazil were submitted to the Infectious Diseases Pathology Branch at the US Centers for Disease Control and Prevention (Atlanta, GA, USA) between December, 2015, and March, 2016. Specimens were assessed by histopathological examination, immunohistochemical assays using a mouse anti-Zika virus antibody, and RT-PCR assays targeting the NS5 and envelope genes. Amplicons of RT-PCR positive cases were sequenced for characterisation of strains.

FINDINGS

Viral antigens were localised to glial cells and neurons and associated with microcalcifications in all three fatal cases with microcephaly. Antigens were also seen in chorionic villi of one of the first trimester placentas. Tissues from all five cases were positive for Zika virus RNA by RT-PCR, and sequence analyses showed highest identities with Zika virus strains isolated from Brazil during 2015.

INTERPRETATION

These findings provide strong evidence of a link between Zika virus infection and different congenital central nervous system malformations, including microcephaly as well as arthrogryposis and spontaneous abortions.

FUNDING

None.

Imaging of congenital Zika virus infection: the route to identification of prognostic factors

Zika virus (ZIKV) has recently emerged as a novel teratogenic agent associated with severe neurological complications. The risk associated with maternal infection remains to be exactly defined but appears to be significant. Like other TORCH agents (toxoplasmosis, other agents, rubella, cytomegalovirus and herpes simplex), it is unlikely that all affected fetuses will be symptomatic at birth. It is therefore urgent to better define the spectrum of anomalies observed in infected fetuses to provide adequate parental counseling. In this review, we provide a comprehensive analysis of major cases described to date and highlight specific prenatal and postnatal radiological findings of congenital ZIKV infection. A total of 19 reports were included in our analysis. ZIKV seemed to harbor a specific tropism for the central nervous system, and anomalies were mostly limited to the brain. Major radiological findings were ventriculomegaly, diffuse calcifications and signs of abnormal gyration as well as cortical development. In addition, a significant number of fetuses suffered from intra uterine growth restriction. Based on these findings, we provide recommendations for adequate radiological monitoring of at-risk pregnancies. © 2016 John Wiley & Sons, Ltd.

Zika virus: from pathogenesis to disease control

Zika virus is a mosquito-borne flavivirus discovered in Uganda in 1947. The virus has emerged in recent years and spread in the Pacific Area and the Americas, where it has caused large human outbreaks. The factors involved in the virus's emergence are still unknown, but probably include its introduction in naïve environments characterised by the presence of high densities of competent Aedes spp. mosquitoes and susceptible human hosts in urban areas. Unique features of Zika virus infection are sexual and transplacental transmission and associated neurological morbidities, i.e. Guillain-Barré syndrome and fetal microcephaly. Diagnosis relies on the detection of viral nucleic acids in biological samples, while detection of a specific antibody response may be inconclusive because of the broad cross-reactivity of antibodies among flaviviruses. Experimental studies have clarified some mechanisms of Zika virus pathogenesis and have identified potential targets for antiviral drugs. In animal models, the virus can infect and efficiently replicate in the placenta and in the brain, and induce fetal demise or neural damage, recapitulating human diseases. These animal models have been used to evaluate candidate vaccines and promising results have been obtained.

Non-vector-borne transmission of Zika virus: A systematic review

BACKGROUND

Increasing numbers of confirmed cases of Zika virus (ZIKV) infection resulting from non-mosquito-borne transmission have been reported.

METHODS

We performed a systematic literature review (PRISMA guidelines) on intrauterine, intrapartum, sexual and animal bite ZIKV transmission. The presence of the virus in breast milk, urine, saliva and blood transfusions was also reviewed.

RESULTS

The search resulted in 285 papers of possible relevance, of which we included 53 in the systematic review. Mother-to-child transmission was most frequently described with adverse infant outcomes including microcephaly, intracranial calcification and fetal death. Zika virus RNA has been detected in amniotic fluid, breast milk, seminal fluid, saliva, urine and blood. Semen and blood products have proved to be infectious. Male-to-female and male-to-male ZIKV transmission is documented. There are contradictory results concerning the infectiousness of breast milk and urine and data on saliva, animal bites, transplantation, needlestick injury and laboratory work are inconclusive.

CONCLUSIONS

Our systematic analysis shows that non-vector-borne ZIKV transmission plays a role in the spread of ZIKV and has great societal impact. It has important public health implications for the prevention and control of ZIKV globally and will be a basis for policy and further research.

Emerging Role of Zika Virus in Adverse Fetal and Neonatal Outcomes

The rapid spread of the Zika virus (ZIKV) in the Americas and its potential association with thousands of suspected cases of microcephaly in Brazil and higher rates of Guillain-Barré syndrome meet the conditions for a Public Health Emergency of International Concern, as stated by the World Health Organization in February 2016. Two months later, the Centers for Disease Control and Prevention (CDC) announced that the current available evidence supports the existence of a causal relationship between prenatal Zika virus infection and microcephaly and other serious brain anomalies. Microcephaly can be caused by several factors, and its clinical course and prognosis are difficult to predict. Other pathogens with proven teratogenicity have been identified long before the current ZIKV epidemic. Despite the growing number of cases with maternal signs of infection and/or presence of ZIKV in tissues of affected newborns or fetuses, it is currently difficult to assess the magnitude of increase of microcephaly prevalence in Brazil, as well as the role of other factors in the development of congenital neurological conditions. Meanwhile, health agencies and medical organizations have issued cautious guidelines advising health care practitioners and expectant couples traveling to, returning from, or living in affected areas. Analogous to dengue virus (DENV) epidemics, ZIKV has the potential to become endemic in all countries infested by Aedes mosquitoes, while new mutations could impact viral replication in humans, leading to increased virulence and consequently heightened chances of viral transmission to additional naive mosquito vectors. Studies are urgently needed to answer the questions surrounding ZIKV and its role in congenital neurological conditions.

Scoping Review of the Zika Virus Literature

The global primary literature on Zika virus (ZIKV) (n = 233 studies and reports, up to March 1, 2016) has been compiled using a scoping review methodology to systematically identify and characterise the literature underpinning this broad topic using methods that are documented, updateable and reproducible. Our results indicate that more than half the primary literature on ZIKV has been published since 2011. The articles mainly covered three topic categories: epidemiology of ZIKV (surveillance and outbreak investigations) 56.6% (132/233), pathogenesis of ZIKV (case symptoms/ outcomes and diagnosis) 38.2% (89/233) and ZIKV studies (molecular characterisation and in vitro evaluation of the virus) 18.5% (43/233). There has been little reported in the primary literature on ZIKV vectors (12/233), surveillance for ZIKV (13/233), diagnostic tests (12/233) and transmission (10/233). Three papers reported on ZIKV prevention/control strategies, one investigated knowledge and attitudes of health professionals and two vector mapping studies were reported. The majority of studies used observational study designs, 89.7% (209/233), of which 62/233 were case studies or case series, while fewer (24/233) used experimental study designs. Several knowledge gaps were identified by this review with respect to ZIKV epidemiology, the importance of potential non-human primates and other hosts in the transmission cycle, the burden of disease in humans, and complications related to human infection with ZIKV. Historically there has been little research on ZIKV; however, given its current spread through Australasia and the Americas, research resources are now being allocated to close many of the knowledge gaps identified in this scoping review. Future updates of this project will probably demonstrate enhanced evidence and understanding of ZIKV and its impact on public health.

Zika crisis in Brazil: challenges in research and development

Infection with the Zika virus (ZIKV) usually causes a mild acute illness, but two major severe syndromes have been described during the epidemic in Brazil: microcephaly and the Guillain-Barré Syndrome. There is now much evidence to show that ZIKV can infect and damage neuronal cells in vitro. In experimental animals, ZIKV has significant neurotropism and can cause brain damage. At present, diagnosis is still a challenge in the field and there is no treatment available. Another major challenge is that one must devise therapies for pregnant women, at all stages of pregnancy. Devising adequate treatment for ZIKV infections represents a challenge that will only be met by the joint effort of the research community.

[Zika virus infection during pregnancy]

A Zika virus epidemic is currently ongoing in the Americas. This virus is linked to congenital infections with potential severe neurodevelopmental dysfunction. However, incidence of fetal infection and whether this virus is responsible of other fetal complications are still unknown. National and international public health authorities recommend caution and several prevention measures. Declaration of Zika virus infection is now mandatory in France. Given the available knowledge on Zika virus, we suggest here a review of the current recommendations for management of pregnancy in case of suspicious or infection by Zika virus in a pregnant woman.

Zika Virus: Implications for Public Health

The World Health Organization has declared the current Zika virus (ZIKV) epidemic a public health emergency of international concern. Lack of vaccines and reliable diagnostic tests, broad geographical distribution of mosquito species that can transmit the virus, and absence of population immunity in newly affected countries are causes for concern. Although most infected persons are asymptomatic, ZIKV has been associated with a rise in cases of neurological complications and fetal central nervous system malformations. This defines such an arbovirus as something whose transmission should be prevented. This review summarizes the current understanding of ZIKV biology and epidemiology, as well as possible interventions to prevent contagion and transmission.