Zika Virus and the Guillain-Barré Syndrome - Case Series from Seven Countries

Neurological manifestations of congenital Zika virus infection

INTRODUCTION

In 2015, it was observed a rise in the number of microcephalic newborns associated with a history of non-specific febrile sickness and rash during pregnancy in Brazil. Since then, microcephaly has emerged as a public health concern. A few months after, the causal relation between congenital microcephaly and the Zika virus was discovered. Zika virus, an arbovirus, is a new TORCH member that leads to congenital infection through vertical transmission and harms the developing brain, disrupting synaptogenesis, and causing other central nervous system lesions.

OBJECTIVE

The purpose of this article is to report the congenital Zika syndrome (CZS) and to emphasize the need for follow-up of the affected children to better know the evolutionary history of this new agent and to optimize the provision of healthcare and improve the quality of life of these patients.

METHODS

We review the most relevant literature about clinical manifestations and neuroimaging findings related to neurotropism of Zika virus to characterize the congenital Zika syndrome and suggest the systematization of some exams and procedures to evaluate children exposed to ZIKV with or without microcephaly, according to the author's own experience.

CONCLUSIONS

Vertical ZIKV infection can cause a wide spectrum of neurological manifestations that go beyond microcephaly, and even the non-microcephalic child should be followed during the first years of life, because infection may be asymptomatic or lead to neuropsicomotor delay, epilepsy, and visual abnormalities. The appropriate prospective multidisciplinary follow-up of these patients aims to understand the natural history of this new agent and to provide a better development and quality of life for them and their families.

History and Emergence of Zika Virus

Zika virus was discovered in East Africa in 1947 by the Rockefeller Foundation during investigations on the ecology of yellow fever. Although it was subsequently shown to have widespread distribution in Africa and Asia, it was not known to cause epidemics until 2007. This paper describes the history of the virus discovery, emergence and evolution as an epidemic virus, and the its evolving clinical spectrum.

Quantifying Zika: Advancing the Epidemiology of Zika With Quantitative Models

When Zika virus (ZIKV) emerged in the Americas, little was known about its biology, pathogenesis, and transmission potential, and the scope of the epidemic was largely hidden, owing to generally mild infections and no established surveillance systems. Surges in congenital defects and Guillain-Barré syndrome alerted the world to the danger of ZIKV. In the context of limited data, quantitative models were critical in reducing uncertainties and guiding the global ZIKV response. Here, we review some of the models used to assess the risk of ZIKV-associated severe outcomes, the potential speed and size of ZIKV epidemics, and the geographic distribution of ZIKV risk. These models provide important insights and highlight significant unresolved questions related to ZIKV and other emerging pathogens.

Infection via mosquito bite alters Zika virus tissue tropism and replication kinetics in rhesus macaques

Mouse and nonhuman primate models now serve as useful platforms to study Zika virus (ZIKV) pathogenesis, candidate therapies, and vaccines, but they rely on needle inoculation of virus: the effects of mosquito-borne infection on disease outcome have not been explored in these models. Here we show that infection via mosquito bite delays ZIKV replication to peak viral loads in rhesus macaques. Importantly, in mosquito-infected animals ZIKV tissue distribution was limited to hemolymphatic tissues, female reproductive tract tissues, kidney, and liver, potentially emulating key features of human ZIKV infections, most of which are characterized by mild or asymptomatic disease. Furthermore, deep sequencing analysis reveals that ZIKV populations in mosquito-infected monkeys show greater sequence heterogeneity and lower overall diversity than in needle-inoculated animals. This newly developed system will be valuable for studying ZIKV disease because it more closely mimics human infection by mosquito bite than needle-based inoculations.

Vector saliva can affect infectivity and pathogenesis of vector-borne viruses, but this hasn’t been studied for Zika virus infection. Here, Dudley et al. show that mosquito-mediated Zika infection of macaques results in altered replication kinetics and greater sequence heterogeneity.

Experimental Zika Virus Inoculation in a New World Monkey Model Reproduces Key Features of the Human Infection

A monkey model of Zika virus (ZIKV) infection is urgently needed to better understand transmission and pathogenesis, given its proven association with fetal brain defects in pregnant women and acute neurological illness. Here we experimentally infected 4 male marmosets with ZIKV (prototype 1947 African strain) and monitored them clinically with sampling of various body fluids and tissues for nearly 3 months. We show that the course of acute infection with ZIKV in these New World monkeys resembles the human illness in many respects, including (1) lack of apparent clinical symptoms in most cases, (2) persistence of the virus in body fluids such as semen and saliva for longer periods of time than in serum, and (3) generation of neutralizing antibodies as well as an antiviral immunological host response. Importantly, ZIKV-infected saliva samples (in addition to serum) were found to be infectious, suggesting potential capacity for viral transmission by the oral route. Re-challenge of a previously infected marmoset with a contemporary outbreak strain SPH2015 from Brazil resulted in continued protection against infection, no viral shedding, and boosting of the immune response. Given the key similarities to human infection, a marmoset model of ZIKV infection may be useful for testing of new drugs and vaccines.

First evidence of Zika virus venereal transmission in Aedes aegypti mosquitoes

BACKGROUND

Aedes aegypti is considered the main Zika virus (ZIKV) vector, and is thought to be responsible for the 2015-2016 outbreak in Brazil. Zika positive Ae. aegypti males collected in the field suggest that vertical and/or venereal transmission of ZIKV may occur.

OBJECTIVES

In this study, we aimed to demonstrate that venereal transmission of ZIKV by Ae. aegypti can occur under laboratory conditions.

METHODS

Ae. aegypti collected in the city of Manaus, confirmed as negative for Zika, Dengue and Chikungunya virus by reverse transcription real-time polymerase chain reaction (RT-qPCR) (AaM3V- strain), were reared under laboratory conditions and used for the experiments. The ZIKV used in this study was isolated from a patient presenting with symptoms; ZIKV was confirmed by RT-qPCR. Experiment 1: virgin male mosquitoes of AaM3V- strain were intrathoracically inoculated with a ZIKV suspension; four days after injection, they were transferred to a cage containing virgin females of AaM3V- strain and left to copulate for five days. Experiment 2: virgin female mosquitoes of AaM3V- strain were orally infected with a ZIKV suspension by blood feeding membrane assay; nine days after blood feeding, they were placed in cages with Ae. aegypti AaM3V- virgin males and left to copulate for four days. After copulation, all mosquitoes were individually evaluated for viral infection by RT-qPCR.

FINDINGS

The mean infection rate in Experiment 1 and Experiment 2 was 45% and 35%, respectively. In both experiments, cycle threshold values ranged from 13 to 35, indicating the presence of viral genomes.

MAIN CONCLUSION

Ae. aegypti males intrathoracically inoculated with a ZIKV suspension are infected and can transmit the virus to uninfected females by mating. Moreover, Ae. aegypti females orally infected with a ZIKV suspension can transmit the virus to uninfected males by copulation. This study shows that ZIKV infection of Ae. aegypti mosquitoes occurs not only during blood feeding, but also during copulation.

Detecting Local Zika Virus Transmission in the Continental United States: A Comparison of Surveillance Strategies

Introduction:

The 2015-2017 Zika virus (ZIKV) epidemic in the Americas has driven efforts to strengthen surveillance systems and to develop interventions, testing, and travel recommendations. In the continental U.S. and Hawaii, where limited transmission has been observed, detecting local transmission is a key public health objective. We assessed the effectiveness of three general surveillance strategies for this situation: testing all pregnant women twice during pregnancy, testing blood donations, and testing symptomatic people who seek medical care in an emergency department (ED).

Methods:

We developed a simulation model for each surveillance strategy and simulated different transmission scenarios with varying population sizes and infection rates. We then calculated the probability of detecting transmission, the number of tests needed, and the number of false positive test results.

Results:

The probability of detecting ZIKV transmission was highest for testing ED patients with Zika symptoms, followed by pregnant women and blood donors, in that order. The magnitude of the difference in probability of detection between strategies depended on the incidence of infection. Testing ED patients required fewer tests and resulted in fewer false positives than surveillance among pregnant women. The optimal strategy identified was to test ED patients with at least two Zika virus disease symptoms. This case definition resulted in a high probability of detection with relatively few tests and false positives.

Discussion:

In the continental U.S. and Hawaii, where local ZIKV transmission is rare, optimizing the probability of detecting infections while minimizing resource usage is particularly important. Local surveillance strategies will be influenced by existing public health system infrastructure, but should also consider the effectiveness of different approaches. This analysis demonstrated differences across strategies and indicated that testing symptomatic ED patients is generally a more efficient strategy for detecting transmission than routine testing of pregnant women or blood donors.

Behavioral, climatic, and environmental risk factors for Zika and Chikungunya virus infections in Rio de Janeiro, Brazil, 2015-16

The burden of arboviruses in the Americas is high and may result in long-term sequelae with infants disabled by Zika virus infection (ZIKV) and arthritis caused by infection with Chikungunya virus (CHIKV). We aimed to identify environmental drivers of arbovirus epidemics to predict where the next epidemics will occur and prioritize municipalities for vector control and eventual vaccination. We screened sera and urine samples (n = 10,459) from residents of 48 municipalities in the state of Rio de Janeiro for CHIKV, dengue virus (DENV), and ZIKV by molecular PCR diagnostics. Further, we assessed the spatial pattern of arbovirus incidence at the municipal and neighborhood scales and the timing of epidemics and major rainfall events. Lab-confirmed cases included 1,717 infections with ZIKV (43.8%) and 2,170 with CHIKV (55.4%) and only 29 (<1%) with DENV. ZIKV incidence was greater in neighborhoods with little access to municipal water infrastructure (r = -0.47, p = 1.2x10^-8). CHIKV incidence was weakly correlated with urbanization (r = 0.2, p = 0.02). Rains began in October 2015 and were followed one month later by the largest wave of ZIKV epidemic. ZIKV cases markedly declined in February 2016, which coincided with the start of a CHIKV outbreak. Rainfall predicted ZIKV and CHIKV with a lead time of 3 weeks each time. The association between rainfall and epidemics reflects vector ecology as the larval stages of Aedes aegypti require pools of water to develop. The temporal dynamics of ZIKV and CHIKV may be explained by the shorter incubation period of the viruses in the mosquito vector; 2 days for CHIKV versus 10 days for ZIKV.

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.

Zika virus in French Polynesia 2013-14: anatomy of a completed outbreak

The Zika virus crisis exemplified the risk associated with emerging pathogens and was a reminder that preparedness for the worst-case scenario, although challenging, is needed. Herein, we review all data reported during the unexpected emergence of Zika virus in French Polynesia in late 2013. We focus on the new findings reported during this outbreak, especially the first description of severe neurological complications in adults and the retrospective description of CNS malformations in neonates, the isolation of Zika virus in semen, the potential for blood-transfusion transmission, mother-to-child transmission, and the development of new diagnostic assays. We describe the effect of this outbreak on health systems, the implementation of vector-borne control strategies, and the line of communication used to alert the international community of the new risk associated with Zika virus. This outbreak highlighted the need for careful monitoring of all unexpected events that occur during an emergence, to implement surveillance and research programmes in parallel to management of cases, and to be prepared to the worst-case scenario.

An update on Zika virus infection

The epidemic history of Zika virus began in 2007, with its emergence in Yap Island in the western Pacific, followed in 2013-14 by a larger epidemic in French Polynesia, south Pacific, where the first severe complications and non-vector-borne transmission of the virus were reported. Zika virus emerged in Brazil in 2015 and was declared a national public health emergency after local researchers and physicians reported an increase in microcephaly cases. In 2016, WHO declared the recent cluster of microcephaly cases and other neurological disorders reported in Brazil a global public health emergency. Similar clusters of microcephaly cases were also observed retrospectively in French Polynesia in 2014. In 2015-16, Zika virus continued its spread to cause outbreaks in the Americas and the Pacific, and the first outbreaks were reported in continental USA, Africa, and southeast Asia. Non-vector-borne transmission was confirmed and Zika virus was established as a cause of severe neurological complications in fetuses, neonates, and adults. This Review focuses on important updates and gaps in the knowledge of Zika virus as of early 2017.

After the epidemic: Zika virus projections for Latin America and the Caribbean

Background

Zika is one of the most challenging emergent vector-borne diseases, yet its future public health impact remains unclear. Zika was of little public health concern until recent reports of its association with congenital syndromes. By 3 August 2017 ∼217,000 Zika cases and ∼3,400 cases of associated congenital syndrome were reported in Latin America and the Caribbean. Some modelling exercises suggest that Zika virus infection could become endemic in agreement with recent declarations from the The World Health Organisation.

Methodology/Principal findings

We produced high-resolution spatially-explicit projections of Zika cases, associated congenital syndromes and monetary costs for Latin America and the Caribbean now that the epidemic phase of the disease appears to be over. In contrast to previous studies which have adopted a modelling approach to map Zika potential, we project case numbers using a statistical approach based upon reported dengue case data as a Zika surrogate. Our results indicate that ∼12.3 (0.7–162.3) million Zika cases could be expected across Latin America and the Caribbean every year, leading to ∼64.4 (0.2–5159.3) thousand cases of Guillain-Barré syndrome and ∼4.7 (0.0–116.3) thousand cases of microcephaly. The economic burden of these neurological sequelae are estimated to be USD ∼2.3 (USD 0–159.3) billion per annum.

Conclusions/Significance

Zika is likely to have significant public health consequences across Latin America and the Caribbean in years to come. Our projections inform regional and federal health authorities, offering an opportunity to adapt to this public health challenge.

In February 2016 the World Health Organisation (WHO) declared Zika virus infection in the Americas as a Public Health Emergency of International Concern (PHEIC). By November 2016, Zika was declared a long-term public health challenge. This change of status implies that Zika is likely to become an endemic problem in the region. Due to the PHEIC status of Zika, most current research has rightly focused on the epidemic stage of the disease; however, it is timely and critical to consider the public health consequences after such epidemic phase. We used one of the largest and most spatially diverse panels of epidemiological surveillance data comprising 12 years of dengue case observations from Brazil and Mexico, and covering an area of over ten million km². State-of-the-art statistical models, and high-resolution (0.5 × 0.5 degrees) climate and demographic data were used to produce spatially-explicit projections of Zika infection for Latin America and the Caribbean. Model projections were then used to estimate the number of cases with neurological sequelae and their economic cost. Our findings indicate that the potential health and economic burden of Zika could be considerably large for the region should it become endemic. The estimated burden of Zika under an endemic state highlights the need for health authorities in the countries at risk to promote preventive and control measures.

Acute Zika Virus Infection as a Risk Factor for Guillain-Barré Syndrome in Puerto Rico

This case-control study conducted during the Zika virus epidemic in Puerto Rico estimates the association between preceding Zika virus infection and subsequent Guillain-Barré syndrome.

Prolonged Zika virus viremia in a patient with Guillain-Barré syndrome in Trinidad and Tobago

An emerging mosquito-borne flavivirus, Zika virus (ZIKV) is a significant public health concern because of the syndromes associated with the infection. In addition, ZIKV is considered a major problem due to large-scale spread of the disease and the possible clinical complications for the central nervous system, especially Guillain-Barré syndrome (GBS) and microcephaly. Since the introduction of ZIKV in the Caribbean, molecular detection of the viral RNA has been utilized as a more specific and sensitive approach to demonstrating acute infection. However, it is generally accepted that the virus has a short viremic period, generally less than 5 days. Serologic testing has the inconvenience of strong cross-reactivity among flaviviruses, such as dengue and yellow fever. As part of the laboratory surveillance activities for Zika and other arboviruses at the Caribbean Public Health Agency, in 2016 a sample from a male who was clinically diagnosed with GBS tested positive for Zika virus by real-time polymerase chain reaction (rRT-PCR). The serum sample had been taken on day 21 after the onset of symptoms. The case had initially been characterized as a typical ZIKV infection (mild fever with a generalized maculopapular rash). Later, weakness of limbs and other peripheral neurological symptoms appeared. Enzyme-linked immunoassay (ELISA) showed that the sample was negative for IgM antibodies against Zika, Chikungunya, and dengue viruses. The plaque reduction neutralization test was positive for ZIKV. This indicated parallel development of viremia and immune response against ZIKV. Recent reports have demonstrated a longer duration of the viremia in ZIKV infections. However, our report is the first one that links the infection with extended viremia and the development in parallel of a GBS case.

Incidence of Guillain-Barré syndrome at a secondary centre during the 2016 zika outbreak

INTRODUCTION

Although Guillain-Barré syndrome is rare, a marked increase in incidence was observed during the 2016 Zika outbreak in the Americas, with no direct causal relationship being apparent in all cases.

METHODS

Cases of febrile exanthematous disease and acute flaccid paralysis were reviewed during the period from 1 August to 15 December, 2016; clinical and biochemical assessment was performed for each case to identify Zika-related Guillain-Barré syndrome.

RESULTS

During the study period, we identified 8 patients (6 men and 2 women) with Zika-related Guillain-Barré syndrome, with the most affected age group being 50-59 years. The highest incidence was in the month of September, with 7 cases. The most frequent symptoms were rash and conjunctivitis, followed by fever. The most common presentation was symmetrical ascending paralysis, present in 7 cases. Cranial nerve VII was the most frequently involved nerve. Only 2 patients presented albuminocytologic dissociation. RT-PCR returned negative results for Zika virus in all patients. All patients received intravenous immunoglobulin and all had a good prognosis. None warranted mechanical ventilation. No deaths were recorded. The cumulative incidence rate was 3.9%, monthly incidence was between 0.04 and 2 cases/month.

CONCLUSIONS

Cases of Guillain-Barré syndrome increased during the Zika outbreak, with an increase in incidence and number of cases per month; however, a direct causal relationship between the 2 conditions could not be demonstrated.

Host genetic background influences diverse neurological responses to viral infection in mice

Infection by Theiler's murine encephalomyelitis virus (TMEV) is a model for neurological outcomes caused by virus infection because it leads to diverse neurological conditions in mice, depending on the strain infected. To extend knowledge on the heterogeneous neurological outcomes caused by TMEV and identify new models of human neurological diseases associated with antecedent infections, we analyzed the phenotypic consequences of TMEV infection in the Collaborative Cross (CC) mouse population. We evaluated 5 different CC strains for outcomes of long-term infection (3 months) and acute vs. early chronic infection (7 vs. 28 days post-infection), using neurological and behavioral phenotyping tests and histology. We correlated phenotypic observations with haplotypes of genomic regions previously linked to TMEV susceptibility to test the hypothesis that genomic diversity within CC mice results in variable disease phenotypes in response to TMEV. None of the 5 strains analyzed had a response identical to that of any other CC strain or inbred strain for which prior data are available, indicating that strains of the CC can produce novel models of neurological disease. Thus, CC strains can be a powerful resource for studying how viral infection can cause different neurological outcomes depending on host genetic background.

Zika virus disease-associated Guillain-Barré syndrome-Barranquilla, Colombia 2015-2016

BACKGROUND

An outbreak of Guillain-Barré syndrome (GBS), a disorder characterized by acute, symmetric limb weakness with decreased or absent deep-tendon reflexes, was reported in Barranquilla, Colombia, after the introduction of Zika virus in 2015. We reviewed clinical data for GBS cases in Barranquilla and performed a case-control investigation to assess the association of suspect and probable Zika virus disease with GBS.

METHODS

We used the Brighton Collaboration Criteria to confirm reported GBS patients in Barranquilla during October 2015-April 2016. In April 2016, two neighborhood and age range-matched controls were selected for each confirmed GBS case-patient. We obtained demographics and antecedent symptoms in the 2-month period before GBS onset for case-patients and the same period for controls. Sera were collected for Zika virus antibody testing. Suspected Zika virus disease was defined as a history of rash and ≥2 other Zika-related symptoms (fever, arthralgia, myalgia, or conjunctivitis). Probable Zika virus disease was defined as suspected Zika virus disease with laboratory evidence of a recent Zika virus or flavivirus infection. Conditional logistic regression adjusted for sex and race/ethnicity was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

We confirmed 47 GBS cases. Incidence increased with age (10-fold higher in those ≥60years versus those <20years). We interviewed 40 case-patients and 79 controls. There was no significant difference in laboratory evidence of recent Zika virus or flavivirus infection between case-patients and controls (OR: 2.2; 95% CI: 0.9-5.1). GBS was associated with having suspected (OR: 3.0, 95% CI: 1.1-8.6) or probable Zika virus disease (OR: 4.6, CI: 1.1-19.0).

CONCLUSIONS

Older individuals and those with suspected and probable Zika virus disease had higher odds of developing GBS.

KEY POINTS

We confirmed a Guillain-Barré syndrome (GBS) outbreak in Barranquilla, Colombia, during October 2015-April 2016. A case-control investigation using neighborhood controls showed an association of suspected and probable Zika virus disease with GBS.

Increased rates of Guillain-Barré syndrome associated with Zika virus outbreak in the Salvador metropolitan area, Brazil

In mid-2015, Salvador, Brazil, reported an outbreak of Guillain-Barré syndrome (GBS), coinciding with the introduction and spread of Zika virus (ZIKV). We found that GBS incidence during April–July 2015 among those ≥12 years of age was 5.6 cases/100,000 population/year and increased markedly with increasing age to 14.7 among those ≥60 years of age. We conducted interviews with 41 case-patients and 85 neighborhood controls and found no differences in demographics or exposures prior to GBS-symptom onset. A higher proportion of case-patients (83%) compared to controls (21%) reported an antecedent illness (OR 18.1, CI 6.9–47.5), most commonly characterized by rash, headache, fever, and myalgias, within a median of 8 days prior to GBS onset. Our investigation confirmed an outbreak of GBS, particularly in older adults, that was strongly associated with Zika-like illness and geo-temporally associated with ZIKV transmission, suggesting that ZIKV may result in severe neurologic complications.

Shortly following the introduction of Zika virus (ZIKV), a type of flavivirus transmitted by mosquitoes, into Brazil in early 2015, the Brazil Ministry of Health began receiving increased reports of a paralyzing condition known as Guillain-Barré syndrome (GBS). The areas with the greatest number of GBS cases appeared to correlate geographically and temporally with the areas reporting the highest rate of ZIKV infections. This association had been previously observed during a ZIKV outbreak in French Polynesia, however, this had not been systematically examined in a case-control investigation for the ZIKV outbreak in South America. In this investigation, the authors found that the occurrence of GBS in the affected population was nearly four times higher than would be expected, and the risk for GBS was particularly elevated among older adults. GBS was associated with ZIKV-like symptoms and with a combination of ZIKV-like symptoms plus laboratory evidence of a recent flavivirus infection. Taken together, these findings provide strong support for and greater understanding of the link between ZIKV and GBS.

Vaccines for emerging infectious diseases: Lessons from MERS coronavirus and Zika virus

The past decade and a half has been characterized by numerous emerging infectious diseases. With each new threat, there has been a call for rapid vaccine development. Pathogens such as the Middle East Respiratory Syndrome coronavirus (MERS-CoV) and the Zika virus represent either new viral entities or viruses emergent in new geographic locales and characterized by novel complications. Both serve as paradigms for the global spread that can accompany new pathogens. In this paper, we review the epidemiology and pathogenesis of MERS-CoV and Zika virus with respect to vaccine development. The challenges in vaccine development and the approach to clinical trial design to test vaccine candidates for disease entities with a changing epidemiology are discussed.

Zika Virus Promotes Neuronal Cell Death in a Non-Cell Autonomous Manner by Triggering the Release of Neurotoxic Factors

Zika virus (ZIKV) has recently caused a worldwide outbreak of infections associated with severe neurological complications, including microcephaly in infants born from infected mothers. ZIKV exhibits high neurotropism and promotes neuroinflammation and neuronal cell death. We have recently demonstrated that N-methyl-d-aspartate receptor (NMDAR) blockade by memantine prevents ZIKV-induced neuronal cell death. Here, we show that ZIKV induces apoptosis in a non-cell autonomous manner, triggering cell death of uninfected neurons by releasing cytotoxic factors. Neuronal cultures infected with ZIKV exhibit increased levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and glutamate. Moreover, infected neurons exhibit increased expression of GluN2B and augmented intracellular Ca²⁺ concentration. Blockade of GluN2B-containing NMDAR by ifenprodil normalizes Ca²⁺ levels and rescues neuronal cell death. Notably, TNF-α and IL-1β blockade decreases ZIKV-induced Ca²⁺ flux through GluN2B-containing NMDARs and reduces neuronal cell death, indicating that these cytokines might contribute to NMDAR sensitization and neurotoxicity. In addition, ZIKV-infected cultures treated with ifenprodil exhibits increased activation of the neuroprotective pathway including extracellular signal-regulated kinase and cAMP response element-binding protein, which may underlie ifenprodil-mediated neuroprotection. Together, our data shed some light on the neurotoxic mechanisms triggered by ZIKV and begin to elucidate how GluN2B-containing NMDAR blockade can prevent neurotoxicity.

Zika Virus: What Have We Learnt Since the Start of the Recent Epidemic?

Zika is a viral disease transmitted mainly by mosquitoes of the genus Aedes. In recent years, it has expanded geographically, changing from an endemic mosquito-borne disease across equatorial Asia and Africa, to an epidemic disease causing large outbreaks in several areas of the world. With the recent Zika virus (ZIKV) outbreaks in the Americas, the disease has become a focus of attention of public health agencies and of the international research community, especially due to an association with neurological disorders in adults and to the severe neurological and ophthalmological abnormalities found in fetuses and newborns of mothers exposed to ZIKV during pregnancy. A large number of studies have been published in the last 3 years, revealing the structure of the virus, how it is transmitted and how it affects human cells. Many different animal models have been developed, which recapitulate several features of ZIKV disease and its neurological consequences. Moreover, several vaccine candidates are now in active preclinical development, and three of them have already entered phase I clinical trials. Likewise, many different compounds targeting viral and cellular components are being tested in in vitro and in experimental animal models. This review aims to discuss the current state of this rapidly growing literature from a multidisciplinary perspective, as well as to present an overview of the public health response to Zika and of the perspectives for the prevention and treatment of this disease.

Neurological Presentation of Zika Virus Infection Beyond the Perinatal Period

PURPOSE OF REVIEW

Our purpose was to summarize the current knowledge about the neurological presentation of Zika virus infection after the perinatal period. Other Flaviviruses infections, such as West Nile virus (WNV) or Japanese encephalitis virus (JEV), can result in neuro-invasive disease such as myelitis, encephalitis, or meningitis. We aimed at describing the specificities of ZV neurological infection.

RECENT FINDINGS

The recent outbreaks demonstrated clearly the neurotropism of ZV. However, by contrast with other Flaviviruses, the most frequent neurological presentation of ZV infection beyond the perinatal period was Guillain-Barré syndrome, especially the demyelination form of GBS. Encephalitis and myelitis seem to occur less frequently after ZV infection than after WNV or JEV infection. The pathophysiology of neurological ZV infections is still poorly understood and no specific treatment is available. Moreover, no data is available about long-term persisting symptoms and possible impairment of patients after the acute clinical episode.

Zika Virus: Obstetric and Pediatric Anesthesia Considerations

As of November 2016, the Florida Department of Health (FDH) and the Centers for Disease Control and Prevention have confirmed more than 4000 travel-related Zika virus (ZIKV) infections in the United States with >700 of those in Florida. There have been 139 cases of locally acquired infection, all occurring in Miami, Florida. Within the US territories (eg, Puerto Rico, US Virgin Islands), >30,000 cases of ZIKV infection have been reported. The projected number of individuals at risk for ZIKV infection in the Caribbean and Latin America approximates 5 million. Similar to Dengue and Chikungunya viruses, ZIKV is spread to humans by infected Aedes aegypti mosquitoes, through travel-associated local transmission, via sexual contact, and through blood transfusions. South Florida is an epicenter for ZIKV infection in the United States and the year-round warm climate along with an abundance of mosquito vectors that can harbor the flavivirus raise health care concerns. ZIKV infection is generally mild with clinical manifestations of fever, rash, conjunctivitis, and arthralgia. Of greatest concern, however, is growing evidence for the relationship between ZIKV infection of pregnant women and increased incidence of abnormal pregnancies and congenital abnormalities in the newborn, now medically termed ZIKA Congenital Syndrome. Federal health officials are observing 899 confirmed Zika-positive pregnancies and the FDH is currently monitoring 110 pregnant women with evidence of Zika infection. The University of Miami/Jackson Memorial Hospital is uniquely positioned just north of downtown Miami and within the vicinity of Liberty City, Little Haiti, and Miami Beach, which are currently "hot spots" for Zika virus exposure and transmissions. As the FDH works fervently to prevent a Zika epidemic in the region, health care providers at the University of Miami and Jackson Memorial Hospital prepare for the clinical spectrum of ZIKV effects as well as the safe perioperative care of the parturients and their affected newborns. In an effort to meet anesthetic preparedness for the care of potential Zika-positive patients and perinatal management of babies born with ZIKA Congenital Syndrome, this review highlights the interim guidelines from the Centers for Disease Control and Prevention and also suggest anesthetic implications and recommendations. In addition, this article reviews guidance for the evaluation and anesthetic management of infants with congenital ZIKV infection. To better manage the perioperative care of affected newborns, this article also reviews the comparative anesthetic implications of babies born with related congenital malformations.

Rapid, Point-of-Care, Paper-Based Plasmonic Biosensor for Zika Virus Diagnosis

Zika virus (ZIKV) is an increasing global health challenge. There is an urgent need for rapid, low-cost, and accurate diagnostic tests that can be broadly distributed and applied in pandemic regions. Here, an innovative, adaptable, and rapidly deployable bioplasmonic paper-based device (BPD) is demonstrated for the detection of ZIKV infection, via quantification of serum anti-ZIKV-nonstructural protein 1 (NS1) IgG and IgM. BPD is based on ZIKV-NS1 protein as a capture element and gold nanorods as plasmonic nanotransducers. The BPD displays excellent sensitivity and selectivity to both anti-ZIKV-NS1 IgG and IgM in human serum. In addition, excellent stability of BPDs at room and even elevated temperature for one month is achieved by metal-organic framework (MOF)-based biopreservation. MOF-based preservation obviates the need for device refrigeration during transport and storage, thus enabling their use in point-of-care and resource-limited settings for ZIKV surveillance. Furthermore, the versatile design (interchangeable recognition element) of BPDs more generally enables their ready adaptation to diagnose other emerging infectious diseases.

Clinical Impact of Non-Congenital Zika Virus Infection in Infants and Children

PURPOSE OF REVIEW

While the Zika virus (ZIKV) has been noted for its distinct neurotropism and identified as a significant cause for a congenital infection syndrome, there has been increased recognition of the importance to better understand the clinical impact of non-congenital ZIKV infection in infants and children. This article reviews reports of perinatal and breast milk transmission of ZIKV and summarizes current clinical outcome data of pediatric non-congenital ZIKV infection.

RECENT FINDINGS

Perinatal transmission and presence of infective ZIKV particles in breast milk have been reported. Most symptomatic non-congenital ZIKV infection in infants and children is mild and self-limited, but long-term follow-up studies are lacking. The mechanism and impact of perinatal and breast milk transmission is unclear. The current WHO infant feeding guidelines in areas of ZIKV transmission support breastfeeding. Unless any scientific data raise concern regarding transmission via breastfeeding, the current guidelines should continue to be followed. Prospective population-based cohort studies to investigate maternal, perinatal, infant, and child outcomes are needed.

Zika Virus Infection

In less than 2 years since entry into the Americas, we have witnessed the emergent spread of Zika virus into large subsets of immunologically naïve human populations and then encountered the devastating effects of microcephaly and brain anomalies that can arise from in utero infection with the virus. Diagnostic evaluation and management of affected infants continues to evolve as our understanding of Zika virus rapidly advances. The development of a safe and effective vaccine holds the potential to attenuate the spread of infection and limit the impact of congenital infection.

Oropharyngeal mucosal transmission of Zika virus in rhesus macaques

Zika virus is present in urine, saliva, tears, and breast milk, but the transmission risk associated with these body fluids is currently unknown. Here we evaluate the risk of Zika virus transmission through mucosal contact in rhesus macaques. Application of high-dose Zika virus directly to the tonsils of three rhesus macaques results in detectable plasma viremia in all animals by 2 days post-exposure; virus replication kinetics are similar to those observed in animals infected subcutaneously. Three additional macaques inoculated subcutaneously with Zika virus served as saliva donors to assess the transmission risk from contact with oral secretions from an infected individual. Seven naive animals repeatedly exposed to donor saliva via the conjunctivae, tonsils, or nostrils did not become infected. Our results suggest that there is a risk of Zika virus transmission via the mucosal route, but that the risk posed by oral secretions from individuals with a typical course of Zika virus infection is low.

Zika virus (ZIKV) is present in body fluids, including saliva, but transmission risk through mucosal contact is not well known. Here, the authors show that oropharyngeal mucosal infection of macaques with a high ZIKV dose results in viremia, but that transmission risk from saliva of infected animals is low.

Zika in the Americas, year 2: What have we learned? What gaps remain? A report from the Global Virus Network

In response to the outbreak of Zika virus (ZIKV) infection in the Western Hemisphere and the recognition of a causal association with fetal malformations, the Global Virus Network (GVN) assembled an international taskforce of virologists to promote basic research, recommend public health measures and encourage the rapid development of vaccines, antiviral therapies and new diagnostic tests. In this article, taskforce members and other experts review what has been learned about ZIKV-induced disease in humans, its modes of transmission and the cause and nature of associated congenital manifestations. After describing the make-up of the taskforce, we summarize the emergence of ZIKV in the Americas, Africa and Asia, its spread by mosquitoes, and current control measures. We then review the spectrum of primary ZIKV-induced disease in adults and children, sites of persistent infection and sexual transmission, then examine what has been learned about maternal-fetal transmission and the congenital Zika syndrome, including knowledge obtained from studies in laboratory animals. Subsequent sections focus on vaccine development, antiviral therapeutics and new diagnostic tests. After reviewing current understanding of the mechanisms of emergence of Zika virus, we consider the likely future of the pandemic.

Progress and Works in Progress: Update on Flavivirus Vaccine Development

Most areas of the globe are endemic for at least one flavivirus, putting billions at risk for infection. This diverse group of viral pathogens causes a range of manifestations in humans from asymptomatic infection to hemorrhagic fever to encephalitis to birth defects and even death. Many flaviviruses are transmitted by mosquitos and have expanded in geographic distribution in recent years, with dengue virus being the most prevalent, infecting approximately 400 million people each year. The explosive emergence of Zika virus in Latin America in 2014 refocused international attention on this medically important group of viruses. Meanwhile, yellow fever has caused major outbreaks in Africa and South America since 2015 despite a reliable vaccine. There is no vaccine for Zika yet, and the only licensed dengue vaccine performs suboptimally in certain contexts. Further lessons are found when considering the experience with Japanese encephalitis virus, West Nile virus, and tickborne encephalitis virus, all of which now have protective vaccination in human or veterinary populations. Thus, vaccination is a mainstay of public health strategy for combating flavivirus infections; however, numerous challenges exist along the path from development to delivery of a tolerable and effective vaccine. Nevertheless, intensification of investment and effort in this area holds great promise for significantly reducing the global burden of disease attributable to flavivirus infection.

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.

Risk of bias and confounding of observational studies of Zika virus infection: A scoping review of research protocols

Introduction

Given the severity and impact of the current Zika virus (ZIKV) outbreak in the Americas, numerous countries have rushed to develop research studies to assess ZIKV and its potential health consequences. In an effort to ensure that studies are comprehensive, both internally and externally valid, and with reliable results, the World Health Organization, the Pan American Health Organization, Institut Pasteur, the networks of Fiocruz, the Consortia for the Standardization of Influenza Seroepidemiology (CONSISE) and the International Severe Acute Respiratory and Emerging Infection Consortium (ISARIC) have generated six standardized clinical and epidemiological research protocols and questionnaires to address key public health questions on ZIKV.

Methods

We conducted a systematic search of ongoing study protocols related to ZIKV research. We analyzed the content of protocols of 32 cohort studies and 13 case control studies for systematic bias that could produce erroneous results. Additionally we aimed to characterize the risks of bias and confounding in observational studies related to ZIKV and to propose ways to minimize them, including the use of six newly standardized research protocols.

Results

Observational studies of ZIKV face an array of challenges, including measurement of exposure and outcomes (microcephaly and Guillain-Barré Syndrome). Potential confounders need to be measured where known and controlled for in the analysis. Selection bias due to non-random selection is a significant issue, particularly in the case-control design, and losses to follow-up is equally important for the cohort design.

Conclusion

Observational research seeking to answer key questions on the ZIKV should consider these restrictions and take precautions to minimize bias in an effort to provide reliable and valid results. Utilization of the standardized research protocols developed by the WHO, PAHO, Institut Pasteur, and CONSISE will harmonize the key methodological aspects of each study design to minimize bias at different stages of the study. Biases need to be considered by researchers implementing the standardized protocols as well as by users of observational epidemiological studies of ZIKV.

Impact of the 2016 Ecuador Earthquake on Zika Virus Cases

OBJECTIVES

To evaluate the impact of the April 2016 7.8-magnitude earthquake in Ecuador on the incidence of Zika virus (ZIKV) cases.

METHODS

We used the national public health surveillance system for reportable transmissible conditions and included suspected and laboratory-confirmed ZIKV cases. We compared the number of cases before and after the earthquake in areas closer to and farther from the epicenter.

RESULTS

From January to July 2016, 2234 patients suspected of having ZIKV infection were reported in both affected and control areas. A total of 1110 patients had a reverse transcription-polymerase chain reaction assay, and 159 were positive for ZIKV. The cumulative incidence of ZIKV in the affected area was 11.1 per 100 000 after the earthquake. The odds ratio of having ZIKV infection in those living in the affected area was 8.0 (95% CI = 4.4, 14.6; P < .01) compared with the control area and adjusted for age, gender, province population, and number of government health care facilities.

CONCLUSIONS

A spike in ZIKV cases occurred after the earthquake. Patients in the area closest to the epicenter had a delay in seeking care.

Biphasic Zika Illness With Rash and Joint Pain

During the current Zika virus (ZIKV) outbreak, acute symptomatic ZIKV infection in adults appears to be a mild-to-moderate, self-limited illness. We present a case of ZIKV rash illness that improved and then relapsed without repeat exposure to ZIKV. Clinicians should be alert for relapses in patients with ZIKV infection.

Zika Virus as an Emerging Neuropathogen: Mechanisms of Neurovirulence and Neuro-Immune Interactions

Zika virus (ZIKV) is an emerging arbovirus of the genus Flaviviridae, which causes a febrile illness and has spread from across the Pacific to the Americas in a short timeframe. Convincing evidence has implicated the ZIKV to incident cases of neonatal microcephaly and a set of neurodevelopmental abnormalities referred to as the congenital Zika virus syndrome. In addition, emerging data points to an association with the ZIKV and the development of the so-called Guillain-Barre syndrome, an acute autoimmune polyneuropathy. Accumulating knowledge suggests that neurovirulent strains of the ZIKV have evolved from less pathogenic lineages of the virus. Nevertheless, mechanisms of neurovirulence and host-pathogen neuro-immune interactions remain incompletely elucidated. This review provides a critical discussion of genetic and structural alterations in the ZIKV which could have contributed to the emergence of neurovirulent strains. In addition, a mechanistic framework of neuro-immune mechanisms related to the emergence of neuropathology after ZIKV infection is discussed. Recent advances in knowledge point to avenues for the development of a putative vaccine as well as novel therapeutic strategies. Nevertheless, there are unique unmet challenges that need to be addressed in this regard. Finally, a research agenda is proposed.

Preventive and therapeutic challenges in combating Zika virus infection: are we getting any closer?

The neuroteratogenic nature of Zika Virus (ZIKV) infection has converted what would have been a tropical disease into a global threat. Zika is transmitted vertically via infected placental cells especially in the first and second trimesters. In the developing central nervous system (CNS), ZIKV can infect and induce apoptosis of neural progenitor cells subsequently causing microcephaly as well as other neuronal complications in infants. Its ability to infect multiple cell types (placental, dermal, and neural) and increased environmental stability as compared to other flaviviruses (FVs) has broadened the transmission routes for ZIKV infection from vector-mediated to transmitted via body fluids. To further complicate the matters, it is genetically similar (about 40%) with the four serotypes of dengue virus (DENV), so much so that it can almost be called a fifth DENV serotype. This homology poses the risk of causing cross-reactive immune responses and subsequent antibody-dependent enhancement (ADE) of infection in case of secondary infections or for immunized individuals. All of these factors complicate the development of a single preventive vaccine candidate or a pharmacological intervention that will completely eliminate or cure ZIKV infection. We discuss all of these factors in detail in this review and conclude that a combinatorial approach including immunization and treatment might prove to be the winning strategy.

Quasispecies composition and evolution of a typical Zika virus clinical isolate from Suriname

The arthropod-borne Zika virus (ZIKV) is currently causing a major international public health threat in the Americas. This study describes the isolation of ZIKV from the plasma of a 29-year-old female traveler that developed typical symptoms, like rash, fever and headache upon return from Suriname. The complete genome sequence including the 5′ and 3′ untranslated regions was determined and phylogenetic analysis showed the isolate clustering within the Asian lineage, close to other viruses that have recently been isolated in the Americas. In addition, the viral quasispecies composition was analyzed by single molecule real time sequencing, which suggested a mutation frequency of 1.4 × 10⁻⁴ for this ZIKV isolate. Continued passaging of the virus in cell culture led to the selection of variants with mutations in NS1 and the E protein. The latter might influence virus binding to cell surface heparan sulfate.

Pericarditis Associated With Acute Zika Virus Infection in a Returning Traveler

Despite the widespread outbreak, few cases of Zika virus associated with cardiac manifestations have been described. We present a case of pericarditis in the setting of an acute, symptomatic Zika virus infection in a traveler returning from St. Thomas. Clinicians should be alert for this potential complication of Zika virus infection.

Zika Virus Persistence in the Central Nervous System and Lymph Nodes of Rhesus Monkeys

Zika virus (ZIKV) is associated with severe neuropathology in neonates as well as Guillain-Barré syndrome and other neurologic disorders in adults. Prolonged viral shedding has been reported in semen, suggesting the presence of anatomic viral reservoirs. Here we show that ZIKV can persist in cerebrospinal fluid (CSF) and lymph nodes (LN) of infected rhesus monkeys for weeks after virus has been cleared from peripheral blood, urine, and mucosal secretions. ZIKV-specific neutralizing antibodies correlated with rapid clearance of virus in peripheral blood but remained undetectable in CSF for the duration of the study. Viral persistence in both CSF and LN correlated with upregulation of mechanistic target of rapamycin (mTOR), proinflammatory, and anti-apoptotic signaling pathways, as well as downregulation of extracellular matrix signaling pathways. These data raise the possibility that persistent or occult neurologic and lymphoid disease may occur following clearance of peripheral virus in ZIKV-infected individuals.

Zika infection and the development of neurological defects

Starting with the outbreak in Brazil, Zika virus (ZIKV) infection has been correlated with severe syndromes such as congenital Zika syndrome and Guillain-Barré syndrome. Here, we review the status of Zika virus pathogenesis in the central nervous system (CNS). One of the main concerns about ZIKV exposure during pregnancy is abnormal brain development, which results in microcephaly in newborns. Recent advances in in vitro research show that ZIKV can infect and obliterate cells from the CNS, such as progenitors, neurons, and glial cells. Neural progenitor cells seem to be the main target of the virus, with infection leading to less cell migration, neurogenesis impairment, cell death and, consequently, microcephaly in newborns. The downsizing of the brain can be directly associated with defective development of the cortical layer. In addition, in vivo investigations in mice reveal that ZIKV can cross the placenta and migrate to fetuses, but with a significant neurotropism, which results in brain damage for the pups. Another finding shows that hydrocephaly is an additional consequence of ZIKV infection, being detected during embryonic and fetal development in mouse, as well as after birth in humans. In spite of the advances in ZIKV research in the last year, the mechanisms underlying ZIKV infection in the CNS require further investigation particularly as there are currently no treatments or vaccines against ZIKV infection.

Severe Thrombocytopenia after Zika Virus Infection, Guadeloupe, 2016

Severe thrombocytopenia during or after the course of Zika virus infection has been rarely reported. We report 7 cases of severe thrombocytopenia and hemorrhagic signs and symptoms in Guadeloupe after infection with this virus. Clinical course and laboratory findings strongly suggest a causal link between Zika virus infection and immune-mediated thrombocytopenia.

Animal Models of Zika Virus Infection, Pathogenesis, and Immunity

Zika virus (ZIKV) is an emerging mosquito-transmitted flavivirus that now causes epidemics affecting millions of people on multiple continents. The virus has received global attention because of some of its unusual epidemiological and clinical features, including persistent infection in the male reproductive tract and sexual transmission, an ability to cross the placenta during pregnancy and infect the developing fetus to cause congenital malformations, and its association with Guillain-Barré syndrome in adults. This past year has witnessed an intensive effort by the global scientific community to understand the biology of ZIKV and to develop pathogenesis models for the rapid testing of possible countermeasures. Here, we review the recent advances in and utility and limitations of newly developed mouse and nonhuman primate models of ZIKV infection and pathogenesis.

Protective efficacy of Zika vaccine in AG129 mouse model

Zika virus (ZIKV) is a mosquito-borne flavivirus that causes asymptomatic infection or presents only mild symptoms in majority of those infected. However, vaccination for ZIKV is a public health priority due to serious congenital and neuropathological abnormalities observed as a sequelae of the virus infection in the recent epidemics. We have developed an inactivated virus vaccine with the African MR 766 strain. Here we show that two doses of the vaccine provided 100% efficacy against mortality and disease following challenge with homotypic MR 766 and the heterotypic FSS 13025 ZIKV strains in the Type I and Type II interferon deficient AG129 mice. Two doses of the vaccine elicited high titer of neutralizing antibodies in Balb/c mice, and the vaccine antisera conferred protection against virus challenge in passively immunized mice. The studies were useful to rationalize vaccine doses for protective efficacy. Furthermore, the vaccine antisera neutralized the homotypic and heterotypic ZIKV strains in vitro with equivalent efficiency. Our study suggests a single ZIKV serotype, and that the development of an effective vaccine may not be limited by the choice of virus strain.

Are anti-ganglioside antibodies associated with proventricular dilatation disease in birds?

The identification of Parrot bornaviruses (PaBV) in psittacine birds with proventricular dilatation disease (PDD) has not been sufficient to explain the pathogenesis of this fatal disease, since not all infected birds develop clinical signs. Although the most accepted theory indicates that PaBV directly triggers an inflammatory response in this disease, another hypothesis suggests the disease is triggered by autoantibodies targeting neuronal gangliosides, and PDD might therefore resemble Guillain-Barré Syndrome (GBS) in its pathogenesis. Experimental inoculation of pure gangliosides and brain-derived ganglioside extracts were used in two different immunization studies. The first study was performed on 17 healthy chickens (Gallus gallus domesticus): 11 chickens were inoculated with a brain ganglioside extract in Freund’s complete adjuvant (FCA) and six chickens inoculated with phosphate-buffered saline. A second study was performed five healthy quaker parrots (Myiopsitta monachus) that were divided into three groups: Two quaker parrots received purified gangliosides in FCA, two received a crude brain extract in FCA, and one control quaker parrot received FCA alone. One chicken developed difficult in walking. Histologically, only a mild perivascular and perineural lymphocytic infiltrate in the proventriculus. Two quaker parrots (one from each treatment group) had mild lymphoplasmacytic encephalitis and myelitis. However, none of the quaker parrots developed myenteric ganglioneuritis, suggesting that autoantibodies against gangliosides in birds are not associated with a condition resembling PDD.

Incidence and clinical characteristics of Guillain-Barré syndrome before the introduction of Zika virus in Puerto Rico

BACKGROUND

Zika virus has been associated with increases in Guillain-Barré syndrome (GBS) incidence. A GBS incidence estimation and clinical description was performed to assess baseline GBS epidemiology before the introduction of Zika virus in Puerto Rico.

METHODS

Hospitalization administrative data from an island-wide insurance claims database and U.S. Census Bureau population estimates provided a crude GBS incidence for 2013. This estimate was adjusted using the proportion of GBS cases meeting Brighton criteria for confirmed GBS from nine reference hospitals. Characteristics of confirmed GBS cases in the same nine hospitals during 2012-2015 are described.

RESULTS

A total of 136 GBS hospitalization claims were filed in 2013 (crude GBS incidence was 3.8 per 100,000 population). The adjusted GBS incidence was 1.7 per 100,000 population. Of 67 confirmed GBS cases during 2012-2015, 66% had an antecedent illness. Median time from antecedent illness to GBS onset was 7days. Most cases (67%) occurred during July-September.

CONCLUSIONS

Puerto Rico's GBS incidence for 2013 was estimated using a combination of administrative data and medical records review; this method could be employed in other regions to monitor GBS incidence before and after the introduction of GBS infectious triggers.