Outbreak of Neurologic Enterovirus Type 71 Disease: A Diagnostic Challenge

New potent EV-A71 antivirals targeting capsid

The enterovirus is a genus of single-stranded, highly diverse positive-sense RNA viruses, including Human Enterovirus A-D and Human Rhinovirus A-C species. They are responsible for numerous diseases and some infections can progress to life-threatening complications, particularly in children or immunocompromised patients. To date, there is no treatment against enteroviruses on the market, except for polioviruses (vaccine) and EV-A71 (vaccine in China). Following a decrease in enterovirus infections during and shortly after the (SARS-Cov2) lockdown, enterovirus outbreaks were once again detected, notably in young children. This reemergence highlights on the need to develop broad-spectrum treatment against enteroviruses. Over the last year, our research team has identified a new class of small-molecule inhibitors showing anti-EV activity. Targeting the well-known hydrophobic pocket in the viral capsid, these compounds show micromolar activity against EV-A71 and a high selectivity index (SI) (5h: EC50, MRC-5 = 0.57 μM, CC50, MRC-5 >20 μM, SI > 35; EC50, RD = 4.38 μM, CC50, RD > 40 μM, SI > 9; 6c: EC50, MRC-5 = 0.29 μM, CC50, MRC-5 >20 μM, SI > 69; EC50, RD = 1.66 μM, CC50, RD > 40 μM, SI > 24; Reference: Vapendavir EC50, MRC-5 = 0.36 μM, CC50, MRC-5 > 20 μM, EC50, RD = 0.53 μM, CC50, RD > 40 μM, SI > 63). The binding mode of these compounds in complex with enterovirus capsids was analyzed and showed a series of conserved interactions. Consequently, 6c and its derivatives are promising candidates for the treatment of enterovirus infections.

Square the Circle: Diversity of Viral Pathogens Causing Neuro-Infectious Diseases

Neuroinfections rank among the top ten leading causes of child mortality globally, even in high-income countries. The crucial determinants for successful treatment lie in the timing and swiftness of diagnosis. Although viruses constitute the majority of infectious neuropathologies, diagnosing and treating viral neuroinfections remains challenging. Despite technological advancements, the etiology of the disease remains undetermined in over half of cases. The identification of the pathogen becomes more difficult when the infection is caused by atypical pathogens or multiple pathogens simultaneously. Furthermore, the modern surge in global passenger traffic has led to an increase in cases of infections caused by pathogens not endemic to local areas. This review aims to systematize and summarize information on neuroinvasive viral pathogens, encompassing their geographic distribution and transmission routes. Emphasis is placed on rare pathogens and cases involving atypical pathogens, aiming to offer a comprehensive and structured catalog of viral agents with neurovirulence potential.

Central nervous system infection in a pediatric population in West Java

Central nervous system (CNS) viral infections are critical causes of morbidity and mortality in children; however, comprehensive data on etiology is lacking in developing countries such as Indonesia. To study the etiology of CNS infections in a pediatric population, 50 children admitted to two hospitals in Bandung, West Java, during 2017-2018 were enrolled in a CNS infection study. Cerebrospinal fluid and serum specimens were tested using molecular, serological, and virus isolation platforms for a number of viral and bacteriological agents. Causal pathogens were identified in 10 out of 50 (20%) and included cytomegalovirus (n = 4), Streptococcus pneumoniae (n = 2), tuberculosis (n = 2), Salmonella serotype Typhi (n = 1) and dengue virus (n = 1). Our study highlights the importance of using a wide range of molecular and serological detection methods to identify CNS pathogens, as well as the challenges of establishing the etiology of CNS infections in pediatric populations of countries with limited laboratory capacity.

Emerging trends and insights in acute flaccid myelitis: a comprehensive review of neurologic manifestations

Acute Flaccid Myelitis (AFM) is a neurological condition in the anterior portion of the spinal cord and can be characterised as paraplegia (paralysis of the lower limbs), and cranial nerve dysfunction. These lesions are caused by the infection due to Enterovirus 68 (EV-D68); a member of the Enterovirus (EV) family belongs to the Enterovirus species within the Picornavirus family and a Polio-like virus. In many cases, the facial, axial, bulbar, respiratory, and extraocular muscles were affected, hence reducing the overall quality of the patient's life. Moreover, severe pathological conditions demand hospitalisation and can cause mortality in a few cases. The data from previous case studies and literature suggest that the prevalence is high in paediatric patients, but careful clinical assessment and management can decrease the risk of mortality and paraplegia. Moreover, the clinical and laboratory diagnosis can be performed by Magnetic resonance imaging (MRI) of the spinal cord followed by Reverse transcription polymerase chain reaction (rRT-PCR) and VP1 seminested PCR assay of the cerebrospinal fluid (CSF), stool, and serum samples can reveal the disease condition to an extent. The primary measure to control the outbreak is social distancing as advised by public health administrations, but more effective ways are yet to discover. Nonetheless, vaccines in the form of the whole virus, live attenuated, sub-viral particles, and DNA vaccines can be an excellent choice to treat these conditions. The review discusses a variety of topics, such as epidemiology, pathophysiology, diagnosis/clinical features, hospitalisation/mortality, management/treatment, and potential future developments.

State of the Art: Acute Encephalitis

Encephalitis is a devastating neurologic disease often complicated by prolonged neurologic deficits. Best practices for the management of adult patients include universal testing for a core group of etiologies, including herpes simplex virus (HSV)-1, varicella zoster virus (VZV), enteroviruses, West Nile virus, and anti-N-methyl-D-aspartate receptor (anti-NMDAR) antibody encephalitis. Empiric acyclovir therapy should be started at presentation and in selected cases continued until a second HSV-1 polymerase chain reaction test is negative. Acyclovir dose can be increased for VZV encephalitis. Supportive care is necessary for other viral etiologies. Patients in whom no cause for encephalitis is identified represent a particular challenge. Management includes repeat brain magnetic resonance imaging, imaging for occult malignancy, and empiric immunomodulatory treatment for autoimmune conditions. Next-generation sequencing (NGS) or brain biopsy should be considered. The rapid pace of discovery regarding autoimmune encephalitis and the development of advanced molecular tests such as NGS have improved diagnosis and outcomes. Research priorities include development of novel therapeutics.

Analysis of the epidemiological trends of enterovirus A in Asia and Europe

BACKGROUND

Enteroviruses have been in massive, cyclical epidemics worldwide. An in-depth understanding of the international epidemiological characteristics of Enterovirus A (EVA) is critical to determining its clinical significance and total disease burden. Although much research has been conducted on EVA epidemiology, there is still a lack of a comprehensive overview of EVA epidemiological characteristics and trends.

OBJECTIVE

EVA nucleic acid sequences from the NCBI virus database were used to summarize the epidemic time (based on the time of specimen collection), spatial and serotype distribution of EVA, and to analyze EVA isolated from cerebrospinal fluid specimens.

METHODS

EVA sequences were searched in NCBI Virus by keyword ("Enterovirus A″ or "EVA") to screen sequences released before December 2021 and sort them to analyze EVA by year, geographic region and serotype prevalence.

RESULTS

The results found 23,041 retrieved nucleic acid sequences with precise collection dates and geographical regions as of December 2021, with Asia accounting for 87%, Europe for 11% and Africa and the Americas for only 2%. Overall, EV-A71, CVA6 and CVA16 are a few of the main prevalent serotypes; and the prevalence characteristics of the different serotypes change over time from place to place.

CONCLUSION

The prevalence of different serotypes of EVA varies considerably over time and space, and we focused on analysing the epidemiological characteristics of EVAs in Asia and Europe and EVAs that invade the nervous system. This study will likely provide important clues for prevention, control and future research in virological surveillance, disease management and vaccine development.

Global emergence of Enterovirus 71: a systematic review

Background

Hand, foot, and mouth disease (HFMD) is a viral infection caused by a virus from the enterovirus genus of picornavirus family that majorly affects children. Though most cases of HFMD do not cause major problems, the outbreaks of Enterovirus 71 (EV71) can produce a high risk of neurological sequelae, including meningoencephalitis, lung difficulties, and mortality. In Asia, HFMD caused by EV71 has emerged as an acutely infectious disease of highly pathogenic potential, which demands the attention of the international medical community.

Main body of the abstract

Some online databases including NCBI, PubMed, Google Scholar, ProQuest, Scopus, and EBSCO were also accessed using keywords relating to the topic for data mining. The paid articles were accessed through the Centre Library facility of Siksha O Anusandhan University. This work describes the structure, outbreak, molecular epidemiology of Enterovirus 71 along with different EV71 vaccines. Many vaccines have been developed such as inactivated whole-virus live attenuated, subviral particles, and DNA vaccines to cure the patients. In Asia–Pacific nations, inactivated EV71 vaccination still confronts considerable obstacles in terms of vaccine standardization, registration, price, and harmonization of pathogen surveillance and measurements.

Short conclusion

HFMD has emerged as a severe health hazard in Asia–Pacific countries in recent decades. In Mainland China and other countries with high HFMD prevalence, the inactivated EV71 vaccination will be a vital tool in safeguarding children's health. When creating inactivated EV71 vaccines, Mainland China ensured maintaining high standards of vaccine quality. The Phase III clinical studies were used to confirm the safety and effectiveness of vaccinations.

Graphical Abstract

Diagnosis and analysis of unexplained cases of childhood encephalitis in Australia using metatranscriptomic sequencing

Encephalitis is most often caused by a variety of infectious agents identified through diagnostic tests utilizing cerebrospinal fluid. We investigated the clinical characteristics and potential aetiological agents of unexplained encephalitis through metagenomic sequencing of residual clinical samples from multiple tissue types and independent clinical review. Forty-three specimens were collected from 18 encephalitis cases with no cause identified by the Australian Childhood Encephalitis study. Samples were subjected to total RNA sequencing ('metatranscriptomics') to determine the presence and abundance of potential pathogens, and to describe the possible aetiologies of unexplained encephalitis. Using this protocol, we identified five RNA and two DNA viruses associated with human infection from both non-sterile and sterile sites, which were confirmed by PCR. These comprised two human rhinoviruses, two human seasonal coronaviruses, two polyomaviruses and one picobirnavirus. Human rhinovirus and seasonal coronaviruses may be responsible for five of the encephalitis cases. Immune-mediated encephalitis was considered likely in six cases and metatranscriptomics did not identify a possible pathogen in these cases. The aetiology remained unknown in nine cases. Our study emphasizes the importance of respiratory viruses in the aetiology of unexplained child encephalitis and suggests that non-central-nervous-system sampling in encephalitis clinical guidelines and protocols could improve the diagnostic yield.

Infectious Meningitis and Encephalitis

Infectious meningitis and encephalitis are associated with significant morbidity and mortality worldwide. Acute bacterial meningitis is rapidly fatal and early recognition and institution of therapy are imperative. Viral meningitis is typically a benign self-limited illness. Chronic meningitis (defined as presenting with >4 weeks of symptoms) is most often caused by tuberculosis and fungal infection. Because the diagnostic testing for tuberculous meningitis is insensitive and cultures often take weeks to grow, therapy is often initiated empirically when the diagnosis is suspected. Human simplex virus encephalitis is the most common cause of encephalitis and requires prompt treatment with intravenous acyclovir.

Susceptibility and cytokine responses of human neuronal cells to multiple circulating EV-A71 genotypes in India

Enterovirus-A71 (EV-A71) associated Hand, foot and mouth disease (HFMD) is a highly contagious viral infection affecting children in Asia–Pacific region and has become a major threat to public health. Although several EV-A71 genotypes (C, D, and G) were isolated in India in recent years, no recognizable outbreak of EV-A71 caused HFMD, Acute Flaccid paralysis (AFP) or encephalitis have been reported so far. It is essential to study the pathogenicity or cell tropism of these Indian isolates in order to understand their tendency to cause disease. We investigated the susceptibility and cytokine responses of indigenous EV-A71 genotypes (D and G) isolated from cases of AFP and genotype C viruses isolated from cases of HFMD and encephalitis, in human cells in-vitro. Although all three EV-A71 genotypes could infect and replicate in human muscle and neuronal cells, the genotype D virus showed a delayed response in human neuronal cells. Quantification of cytokine secretion in response to these isolates followed by confirmation with gene expression assays in human neuronal cells revealed significantly higher secretion of pro-inflammatory cytokines TNF-α IL-8, IL-6, IP-10 (p < 0.001) in G genotype infected cells as compared to pathogenic C genotypes whereas the genotype D virus could not induce any of the inflammatory cytokines. These findings will help to better understand the host response to indigenous EV-A71 genotypes for management of future EV-A71 outbreaks in India, if any.

Update on Viral Infections Involving the Central Nervous System in Pediatric Patients

Infections of the central nervous system (CNS) are mainly caused by viruses, and these infections can be life-threatening in pediatric patients. Although the prognosis of CNS infections is often favorable, mortality and long-term sequelae can occur. The aims of this narrative review were to describe the specific microbiological and clinical features of the most frequent pathogens and to provide an update on the diagnostic approaches and treatment strategies for viral CNS infections in children. A literature analysis showed that the most common pathogens worldwide are enteroviruses, arboviruses, parechoviruses, and herpesviruses, with variable prevalence rates in different countries. Lumbar puncture (LP) should be performed as soon as possible when CNS infection is suspected, and cerebrospinal fluid (CSF) samples should always be sent for polymerase chain reaction (PCR) analysis. Due to the lack of specific therapies, the management of viral CNS infections is mainly based on supportive care, and empiric treatment against herpes simplex virus (HSV) infection should be started as soon as possible. Some researchers have questioned the role of acyclovir as an empiric antiviral in older children due to the low incidence of HSV infection in this population and observed that HSV encephalitis may be clinically recognizable beyond neonatal age. However, the real benefit-risk ratio of selective approaches is unclear, and further studies are needed to define appropriate indications for empiric acyclovir. Research is needed to find specific therapies for emerging pathogens. Moreover, the appropriate timing of monitoring neurological development, performing neuroimaging evaluations and investigating the effectiveness of rehabilitation during follow-up should be evaluated with long-term studies.

First evidence of enterovirus A71 and echovirus 30 in Uruguay and genetic relationship with strains circulating in the South American region

Human enteroviruses (EVs) comprise more than 100 types of coxsackievirus, echovirus, poliovirus and numbered enteroviruses, which are mainly transmitted by the faecal-oral route leading to diverse diseases such as aseptic meningitis, encephalitis, and acute flaccid paralysis, among others. Since enteroviruses are excreted in faeces, wastewater-based epidemiology approaches are useful to describe EV diversity in a community. In Uruguay, knowledge about enteroviruses is extremely limited. This study assessed the diversity of enteroviruses through Illumina next-generation sequencing of VP1-amplicons obtained by RT-PCR directly applied to viral concentrates of 84 wastewater samples collected in Uruguay during 2011-2012 and 2017-2018. Fifty out of the 84 samples were positive for enteroviruses. There were detected 27 different types belonging to Enterovirus A species (CVA2-A6, A10, A16, EV-A71, A90), Enterovirus B species (CVA9, B1-B5, E1, E6, E11, E14, E21, E30) and Enterovirus C species (CVA1, A13, A19, A22, A24, EV-C99). Enterovirus A71 (EV-A71) and echovirus 30 (E30) strains were studied more in depth through phylogenetic analysis, together with some strains previously detected by us in Argentina. Results unveiled that EV-A71 sub-genogroup C2 circulates in both countries at least since 2011-2012, and that the C1-like emerging variant recently entered in Argentina. We also confirmed the circulation of echovirus 30 genotypes E and F in Argentina, and reported the detection of genotype E in Uruguay. To the best of our knowledge this is the first report of the EV-A71 C1-like emerging variant in South-America, and the first report of EV-A71 and E30 in Uruguay.

A Case Report of Acute Flaccid Paralysis Caused by Enterovirus D68 Infection: The Beginning of a Polio-Like Epidemic?

Enterovirus D68 (EV-D68) is a non-polio enterovirus that occasionally causes respiratory illnesses. EV-D68 infections have occurred over the last couple of years and have a high prevalence worldwide. This virus has recently been linked to acute flaccid paralysis and particularly affects children. We report the case of a young adult who presented with acute neurological manifestations along with respiratory involvement. EV-D68 was detected in the patient’s broncho-alveolar lavage and was followed by a prolonged recovery period. Clinicians should consider EV-D68 infection in the differential diagnosis of acute flaccid paralysis (AFP) and respiratory failure.

The role of antibody indexes in clinical virology

BACKGROUND

Serological techniques are an essential part of the diagnostic tools used in clinical virology. Among these techniques, antibody indexes are not novel, but do require specific expertise. Their niche has expanded substantially in recent years due to increasing evidence of their performance to diagnose viral infections.

OBJECTIVES

This narrative review describes the background and clinical applications of antibody indexes. The first objective is to provide an overview of the theoretical background, insights for implementation, limitations and pitfalls. The second objective is to review the available evidence for the diagnostic performance, with a specific focus on viral encephalitis and uveitis.

SOURCES

A comprehensive literature search was performed in PubMed, including original studies and reviews, with no time limit on the studies included. The following search terms were used: antibody index, Goldmann-Witmer coefficient, Reibergram, viral encephalitis, viral uveitis, herpes simplex virus, varicella zoster virus, cytomegalovirus, Epstein-Barr virus, rubella virus, measles virus, enterovirus, influenza virus, flaviviruses.

CONTENT

Antibody indexes can support the diagnosis of a spectrum of viral infections in immune privileged sites such as the central nervous system and the eye, through the demonstration of virus-specific intrathecal or intraocular antibody production. This is especially useful in situations where PCR has a lower positivity rate: infections with rapid viral clearance due to natural immunity or treatment and chronic stages of viral infections.

IMPLICATIONS

Antibody indexes expand the clinical microbiologist's diagnostic toolbox. Careful interpretation of the results of these assays is crucial and further standardization of methods is required to improve interchangeability of results between laboratories.

Causes and Clinical Features of Childhood Encephalitis: A Multicenter, Prospective Cohort Study

BACKGROUND

We aimed to determine the contemporary causes, clinical features, and short-term outcome of encephalitis in Australian children.

METHODS

We prospectively identified children (≤14 years of age) admitted with suspected encephalitis at 5 major pediatric hospitals nationally between May 2013 and December 2016 using the Paediatric Active Enhanced Disease Surveillance (PAEDS) Network. A multidisciplinary expert panel reviewed cases and categorized them using published definitions. Confirmed encephalitis cases were categorized into etiologic subgroups.

RESULTS

From 526 cases of suspected encephalitis, 287 children met criteria for confirmed encephalitis: 57% (95% confidence interval [CI], 52%-63%) had infectious causes, 10% enterovirus, 10% parechovirus, 8% bacterial meningoencephalitis, 6% influenza, 6% herpes simplex virus (HSV), and 6% Mycoplasma pneumoniae; 25% (95% CI, 20%-30%) had immune-mediated encephalitis, 18% acute disseminated encephalomyelitis, and 6% anti-N-methyl-d-aspartate receptor encephalitis; and 17% (95% CI, 13%-21%) had an unknown cause. Infectious encephalitis occurred in younger children (median age, 1.7 years [interquartile range {IQR}, 0.1-6.9]) compared with immune-mediated encephalitis (median age, 7.6 years [IQR, 4.6-12.4]). Varicella zoster virus encephalitis was infrequent following high vaccination coverage since 2007. Thirteen children (5%) died: 11 with infectious causes (2 influenza; 2 human herpesvirus 6; 2 group B Streptococcus; 2 Streptococcus pneumoniae; 1 HSV; 1 parechovirus; 1 enterovirus) and 2 with no cause identified. Twenty-seven percent (95% CI, 21%-31%) of children showed moderate to severe neurological sequelae at discharge.

CONCLUSIONS

Epidemic viral infections predominated as causes of childhood encephalitis in Australia. The leading causes include vaccine-preventable diseases. There were significant differences in age, clinical features, and outcome among leading causes. Mortality or short-term neurological morbidity occurred in one-third of cases.

Epidemiology and Sequence-Based Evolutionary Analysis of Circulating Non-Polio Enteroviruses

Enteroviruses (EVs) are positive-sense RNA viruses, with over 50,000 nucleotide sequences publicly available. While most human infections are typically associated with mild respiratory symptoms, several different EV types have also been associated with severe human disease, especially acute flaccid paralysis (AFP), particularly with endemic members of the EV-B species and two pandemic types—EV-A71 and EV-D68—that appear to be responsible for recent widespread outbreaks. Here we review the recent literature on the prevalence, characteristics, and circulation dynamics of different enterovirus types and combine this with an analysis of the sequence coverage of different EV types in public databases (e.g., the Virus Pathogen Resource). This evaluation reveals temporal and geographic differences in EV circulation and sequence distribution, highlighting recent EV outbreaks and revealing gaps in sequence coverage. Phylogenetic analysis of the EV genus shows the relatedness of different EV types. Recombination analysis of the EV-A species provides evidence for recombination as a mechanism of genomic diversification. The absence of broadly protective vaccines and effective antivirals makes human enteroviruses important pathogens of public health concern.

Neutralizing antibody against Enterovirus-A71 in Thai children: A longitudinal study from birth to age 4 years

Thailand is one of the countries in the Asia-pacific region that has been most affected by the Enterovirus-A71 (EV-A71) epidemic. An individual who is susceptible to EV-A71 may also be infected asymptomatically, thus, a serological assay is a useful tool to estimate the cumulative incidence of infection in the community and to provide guidance for vaccination scheduling. There have been several candidate EV-A71 vaccines, of which three have been approved and licensed in China. The population target for EV-A71 vaccine is children younger than three years of age. In Thailand, there are limited data available on the seroprevalence of EV-A71 neutralizing (NT) antibodies and the timing of seroconversion in children. This study aims to investigate the seroprevalence and seroconversion rate of EV-A71 NT antibody in a cohort of Thai children. Sera were collected at the King Chulalongkorn Memorial Hospital in Bangkok, Thailand from 100 children between 2015 and 2020. Maternal sera were collected on the day of delivery. Serum samples from children were collected at birth (month 0) and at 2, 7, 18, 24, 36, and 48 months of age to test for EV-A71 NT antibody titers using an enzyme-linked immunosorbent assay (ELISA)-based microneutralization test. The seroprotection rate (NT antibody ≥1:16) in children at months 0, 2, 7, 18, 24, 36, and 48 was 81.0%, 60.0%, 9.0%, 10.0%, 13.0%, 17.0%, and 37.1%, respectively. The seroprotection rate was lowest at month 7 due to waning of the maternal antibody and the immunity of children increased with increasing age. At 48 months of age, less than 40% of children were seroprotected. Children at the age of 6 months should be considered a primary target for vaccination.

Enterovirus-related rhombencephalitis and myelitis in the third trimester of pregnancy: A case report highlighting clinico-radiological findings at diagnosis and follow-up

Rhombencephalitis (RE) refers to inflammatory diseases involving the brainstem and cerebellum. Although RE is a rare entity, it is associated with high morbidity and mortality. The management of such patients is often challenging in terms of identifying the etiology and defining prognosis. Infections, autoimmune and paraneoplastic conditions are commonly implicated. Patients with RE often present with a biphasic illness with an initial flu-like syndrome followed by brainstem dysfunction. CSF pleocytosis, abnormal brain MRI findings, isolation of organism or molecular (PCR/antigen) detection in CSF/blood cultures/stool samples and nasal/rectal swabs help in arriving at a definitive or probable diagnosis. Prompt aggressive treatment with antibacterial and antiviral drugs and/or immunoglobulins along with supportive therapy is crucial for avoiding a poor outcome. We present a case report of a 28-year old female patient who developed RE and myelitis in the third trimester of pregnancy. We aim to highlight the highly suggestive radiological findings which corroborated with the clinical diagnosis of enterovirus infection. The patient's radiological follow-up and neurological sequalae are also described. To the best of our knowledge, ours is the first report which describes the MRI features of this clinical scenario in the third trimester of pregnancy, and also the subsequent clinico-radiological follow up.

Acute Flaccid Myelitis in Children in Zhejiang Province, China

In July-December 2018, an outbreak of polio-like acute flaccid myelitis (AFM) occurred in Zhejiang province, China. Enterovirus (EV)-D68 infection has been reported to be associated with AFM. This study aimed to investigate the clinical presentation, laboratory findings, and outcomes of AFM patients. We investigated the clinical and virologic information regarding the AFM patients, and real-time PCR, sequencing, and phylogenetic analysis were used to investigate the cause of AFM. Eighteen cases met the definition of AFM, with a median age of 4.05 years (range, 0.9-9 years), and nine (50%) were EV-D68 positive. Symptoms included acute flaccid limb weakness and cranial nerve dysfunction. On magnetic resonance imaging, 11 (61.1%) patients had spinal gray matter abnormalities. Electromyography results of 16 out of 17 patients (94.1%) were abnormal. Cerebrospinal fluid (CSF) pleocytosis was common (94.4%), while CSF protein concentration was normal in all patients. There was little improvement after early aggressive therapy. Phylogenetic analysis revealed that EV-D68 subclade B3 was the predominant lineage circulating in Zhejiang province in 2018.

Molecular Pathogenicity of Enteroviruses Causing Neurological Disease

Enteroviruses are single-stranded positive-sense RNA viruses that primarily cause self-limiting gastrointestinal or respiratory illness. In some cases, these viruses can invade the central nervous system, causing life-threatening neurological diseases including encephalitis, meningitis and acute flaccid paralysis (AFP). As we near the global eradication of poliovirus, formerly the major cause of AFP, the number of AFP cases have not diminished implying a non-poliovirus etiology. As the number of enteroviruses linked with neurological disease is expanding, of which many had previously little clinical significance, these viruses are becoming increasingly important to public health. Our current understanding of these non-polio enteroviruses is limited, especially with regards to their neurovirulence. Elucidating the molecular pathogenesis of these viruses is paramount for the development of effective therapeutic strategies. This review summarizes the clinical diseases associated with neurotropic enteroviruses and discusses recent advances in the understanding of viral invasion of the central nervous system, cell tropism and molecular pathogenesis as it correlates with host responses.

Genomic and serologic characterization of enterovirus A71 brainstem encephalitis

Objective

In 2016, Catalonia experienced a pediatric brainstem encephalitis outbreak caused by enterovirus A71 (EV-A71). Conventional testing identified EV in the periphery but rarely in CSF. Metagenomic next-generation sequencing (mNGS) and CSF pan-viral serology (VirScan) were deployed to enhance viral detection and characterization.

Methods

RNA was extracted from the CSF (n = 20), plasma (n = 9), stool (n = 15), and nasopharyngeal samples (n = 16) from 10 children with brainstem encephalitis and 10 children with meningitis or encephalitis. Pathogens were identified using mNGS. Available CSF from cases (n = 12) and pediatric other neurologic disease controls (n = 54) were analyzed with VirScan with a subset (n = 9 and n = 50) validated by ELISA.

Results

mNGS detected EV in all samples positive by quantitative reverse transcription polymerase chain reaction (qRT-PCR) (n = 25). In qRT-PCR-negative samples (n = 35), mNGS found virus in 23% (n = 8, 3 CSF samples). Overall, mNGS enhanced EV detection from 42% (25/60) to 57% (33/60) (p-value = 0.013). VirScan and ELISA increased detection to 92% (11/12) compared with 46% (4/12) for CSF mNGS and qRT-PCR (p-value = 0.023). Phylogenetic analysis confirmed the EV-A71 strain clustered with a neurovirulent German EV-A71. A single amino acid substitution (S241P) in the EVA71 VP1 protein was exclusive to the CNS in one subject.

Conclusion

mNGS with VirScan significantly increased the CNS detection of EVs relative to qRT-PCR, and the latter generated an antigenic profile of the acute EV-A71 immune response. Genomic analysis confirmed the close relation of the outbreak EV-A71 and neuroinvasive German EV-A71. A S241P substitution in VP1 was found exclusively in the CSF.

Viral encephalitis: a practical review on diagnostic approach and treatment

OBJECTIVES

To review the diagnostic criteria for encephalitis and encephalopathy of presumed infectious etiology, as well as the diagnostic workup for viral encephalitis and its treatment approaches. The authors also intended to summarize relevant information on specific viruses frequently found in Brazil.

SOURCE OF DATA

Literature search on Pubmed/MEDLINE using the following keywords: "viral", "encephalitis", "child", or "adolescents", filtering for articles on humans and in English.

SUMMARY OF DATA

Viral encephalitis is the most common cause of encephalitis and is responsible for high rates of morbidity, permanent neurologic sequelae, and according to the virus, may have high mortality rates. The most common etiologies are herpesviruses 1 and 2 (HSV-1 and HSV-2), non-polio enterovirus, and arboviruses (in Brazil, dengue, Zika, and chikungunya). Other relevant etiologies are seasonal influenza, cytomegalovirus (CMV), Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), and the re-emergent measles.

CONCLUSION

Clinical data, laboratory results, and neuroimaging findings support the diagnosis of encephalitis and the specific viral etiology. To increase the likelihood of etiologic confirmation, it is important to know the best approach to collecting samples and to choose the best identification technique for each virus. The differential diagnosis of viral encephalitis includes other infections and immune-mediated inflammatory central nervous system disorders.

Clinical characteristics of enterovirus A71 neurological disease during an outbreak in children in Colorado, USA, in 2018: an observational cohort study

BACKGROUND

In May, 2018, Children's Hospital Colorado noted an outbreak of enterovirus A71 (EV-A71) neurological disease. We aimed to characterise the clinical features of EV-A71 neurological disease during this outbreak.

METHODS

In this retrospective observational cohort study, children (younger than 18 years) who presented to Children's Hospital Colorado (Aurora, CO, USA) between March 1 and November 30, 2018, with neurological disease (defined by non-mutually exclusive criteria, including meningitis, encephalitis, acute flaccid myelitis, and seizures) and enterovirus detected from any biological specimen were eligible for study inclusion. The clinical characteristics of children with neurological disease associated with EV-A71 were compared with those of children with neurological disease associated with other enteroviruses during the same period. To explore the differences in clinical presentation of acute flaccid myelitis, we also used a subgroup analysis to compare clinical findings in children with EV-A71-associated acute flaccid myelitis during the study period with these findings in those with enterovirus D68 (EV-D68)-associated acute flaccid myelitis at the same hospital between 2013 and 2018.

FINDINGS

Between March 10 and Nov 10, 2018, 74 children presenting to Children's Hospital Colorado were found to have enterovirus neurological disease; EV-A71 was identified in 43 (58%) of these children. The median age of the children with EV-A71 neurological disease was 22·7 months (IQR 4·0-31·9), and most of these children were male (34 [79%] children). 40 (93%) children with EV-A71 neurological disease had findings suggestive of meningitis, 31 (72%) children showed evidence of encephalitis, and ten (23%) children met our case definition of acute flaccid myelitis. All children with EV-A71 disease had fever and 18 (42%) children had hand, foot, or mouth lesions at or before neurological onset. Children with EV-A71 disease were best differentiated from those with other enteroviruses (n=31) by the neurological findings of myoclonus, ataxia, weakness, and autonomic instability. Of the specimens collected from children with EV-A71, this enterovirus was detected in 94% of rectal, 79% of oropharyngeal, 56% of nasopharyngeal, and 20% of cerebrospinal fluid specimens. 39 (93%) of 42 children with EV-A71 neurological disease who could be followed up showed complete recovery by 1-2 months. Compared with children with EV-D68-associated acute flaccid myelitis, children with EV-A71-associated acute flaccid myelitis were younger, showed neurological onset earlier after prodromal symptom onset, had milder weakness, showed more rapid improvement, and were more likely to completely recover.

INTERPRETATION

This outbreak of EV-A71 neurological disease, the largest reported in the Americas, was characterised by fever, myoclonus, ataxia, weakness, autonomic instability, and full recovery in most patients. Because EV-A71 epidemiology outside of Asia remains difficult to predict, identification of future outbreaks will be aided by prompt recognition of these distinct clinical findings, testing of non-sterile and sterile site specimens, and enhanced enterovirus surveillance.

FUNDING

None.

Acute Flaccid Myelitis in the United States: 2015-2017

BACKGROUND

Acute flaccid myelitis (AFM) is a neurologic condition characterized by flaccid limb weakness. After a large number of reports of AFM in 2014, the Centers for Disease Control and Prevention began standardized surveillance in the United States to characterize the disease burden and explore potential etiologies and epidemiologic associations.

METHODS

Persons meeting the clinical case criteria of acute flaccid limb weakness from January 1, 2015, through December 31, 2017, were classified as confirmed (spinal cord gray matter lesions on MRI) or probable (white blood cell count >5 cells per mm³ in cerebrospinal fluid [CSF]). We describe clinical, radiologic, laboratory, and epidemiologic findings of pediatric patients (age ≤21 years) confirmed with AFM.

RESULTS

Of 305 children reported from 43 states, 193 were confirmed and 25 were probable. Of confirmed patients, 61% were male, with a median age of 6 years (range: 3 months to 21 years; interquartile range: 3 to 10 years). An antecedent respiratory or febrile illness was reported in 79% with a median of 5 days (interquartile range: 2 to 7 days) before limb weakness. Among 153 sterile-site specimens (CSF and serum) submitted to the Centers for Disease Control and Prevention, coxsackievirus A16 was detected in CSF and serum of one case patient and enterovirus D68 was detected in serum of another. Of 167 nonsterile site (respiratory and stool) specimens, 28% tested positive for enterovirus or rhinovirus.

CONCLUSIONS

AFM surveillance data suggest a viral etiology, including enteroviruses. Further study is ongoing to better characterize the etiology, pathogenesis, and risk factors of this rare condition.

Central nervous system (CNS) enterovirus infections: A single center retrospective study on clinical features, diagnostic studies, and outcome

Enteroviruses (EV) are responsible for a large number of meningoencephalitis cases, especially in children. The objective of this study was to identify modes of diagnosis including the significance of respiratory and cerebrospinal fluid samples, associated clinical characteristics, inpatient management, and outcome of individuals with EV infections of the central nervous system (CNS). Electronic medical records of individuals with enterovirus infections of the CNS who presented to the Columbia University Irving Medical Center and Children's Hospital of New York between January 1, 2012 and December 31, 2017 were reviewed retrospectively for demographic, epidemiological, and clinical data. The median age overall was 1.7 months (interquartile range 14 years) and most (62.4%) were male. The majority of CNS infections presented as meningitis (95.7%) and occurred in the summer (45.2%) and fall seasons (37.6%). Eighty-five cases (91.4%) demonstrated EV positivity in cerebrospinal fluid, thirty cases (32.3%) exhibited both cerebrospinal fluid and respiratory positivity, and eight cases (8.6%) exhibited respiratory positivity with coinciding neurological findings. Eighty-nine individuals overall (95.7%) received antibiotics and 37 (39.8%) received antiviral treatment. All surviving individuals had favorable Modified Rankin Scores (MRS) within the zero to two ranges upon discharge. Testing respiratory samples in addition to cerebrospinal fluid was found to be an important diagnostic tool in EV-associated cases. While clinical outcomes were favorable for an overwhelming majority of cases, etiological understanding of CNS infections is essential for identifying ongoing and changing epidemiological patterns and aid in improving the diagnosis and treatment.

Molecular epidemiology of enteroviruses in Cyprus 2008-2017

Enteroviruses (EVs) are associated with a broad spectrum of disease manifestations, including aseptic meningitis, encephalitis, hand, foot and mouth disease, acute flaccid paralysis and acute flaccid myelitis with outbreaks being reported frequently world-wide. The aim of this study was the molecular characterization of all enteroviruses detected in Cyprus in the ten-year period from January 2008 and December 2017 as well as a description of the circulation patterns associated with the most frequently encountered genotypes. For this purpose, serum, cerebrospinal fluid, nasal swab, skin swab and/or stool samples from 2666 patients with a suspected EV infection were analysed between January 2008 and December 2017. Enteroviruses were detected in 295 (11.1%) patients, which were then investigated further for epidemiological analysis by VP1 genotyping. Overall, 24 different enterovirus types belonging to three different species were identified. The predominant species was EV-B (209/295, 71%), followed by species EV-A (77/295, 26.1%). Only one virus belonged to species EV-D, whereas EV-C enteroviruses were not identified at all. The most frequent genotypes identified were echovirus 30 (26.1%), echovirus 6 (14.2%) and coxsackievirus A6 (10.9%). While Echovirus 30 and echovirus 6 frequency was significantly higher in patients older than 3 years of age, the opposite was observed for CV-A16 and EV-A71, which dominated in young children less than 3 years. Importantly, for the current study period a significant increase of previously only sporadically observed EV-A types, such as EV-A71 and CV-A16 was noted. A phylogenetic analysis of EV-A71 showed that the majority of the EV-A71 strains from Cyprus belonged to sub-genogroup C1 and C2, with the exception of one C4 strain that was observed in 2011. The data presented provide a comprehensive picture of enteroviruses circulating in Cyprus over the last decade and will be helpful to clinicians and researchers involved in the treatment, prevention and control of enteroviral infections by helping interpret trends in enteroviral diseases by associating them with circulating serotypes, for studying the association of enteroviruses with clinical manifestations and develop strategies for designing future EV vaccines.

Diagnostic Testing in Central Nervous System Infection

Patients with central nervous system (CNS) infection experience very high levels of morbidity and mortality, in part because of the many challenges inherent to the diagnosis of CNS infection and identification of a causative pathogen. The clinical presentation of CNS infection is nonspecific, so clinicians must often order and interpret many diagnostic tests in parallel. This can be a daunting task given the large number of potential pathogens and the availability of different testing modalities. Here, we review traditional diagnostic techniques including Gram stain and culture, serology, and polymerase chain reaction (PCR). We highlight which of these are recommended for the pathogens most commonly tested among U.S. patients with suspected CNS infection. Finally, we describe the newer broad-range diagnostic approaches, multiplex PCR and metagenomic sequencing, which are increasingly used in clinical practice.

Enterovirus A71 Infection and Neurologic Disease, Madrid, Spain, 2016

For children with brainstem encephalitis or encephalomyelitis, clinicians should look for enterovirus and not limit testing to cerebrospinal fluid.

We conducted an observational study from January 2016 through January 2017 of patients admitted to a reference pediatric hospital in Madrid, Spain, for neurologic symptoms and enterovirus infection. Among the 30 patients, the most common signs and symptoms were fever, lethargy, myoclonic jerks, and ataxia. Real-time PCR detected enterovirus in the cerebrospinal fluid of 8 patients, nasopharyngeal aspirate in 17, and anal swab samples of 5. The enterovirus was genotyped for 25 of 30 patients; enterovirus A71 was the most common serotype (21/25) and the only serotype detected in patients with brainstem encephalitis or encephalomyelitis. Treatment was intravenous immunoglobulins for 21 patients and corticosteroids for 17. Admission to the pediatric intensive care unit was required for 14 patients. All patients survived. At admission, among patients with the most severe disease, leukocytes were elevated. For children with brainstem encephalitis or encephalomyelitis, clinicians should look for enterovirus and not limit testing to cerebrospinal fluid.

Epidemiological study on hand, foot and mouth disease in Tongzhou District, Beijing, 2013-2017

Objective

To study the epidemiological characteristics of hand, foot and mouth disease (HFMD) in Tongzhou District, Beijing between 2013 and 2017.

Methods

Data on HFMD infections from 1 January 2013 to 31 December 2017 were collected from the Notifiable Infectious Diseases Reporting Information System and analysed. Serotyping of enteroviruses from samples from patients with HFMD was undertaken using reverse transcription–polymerase chain reaction.

Results

A total of 15 341 patients with HFMD were reported and 32 patients (0.2%) were classified as having severe HFMD. The annual mean incidence rate of HFMD was 219.3/100 000 of the general population. The incidence and case-severity rates of HFMD generally decreased between 2013 and 2017. In the floating migrant population, the incidence and cases-severity rates of HFMD were significantly higher than in the local population. The peak incidence and severity-case rates were at 2 years of age and > 90% of patients were ≤5 years. Enterovirus A71 and Coxsackievirus A16 were the predominant pathogens in 2013–2017.

Conclusions

During the 5-year period 2013–2017, the incidence rate and case-severity rate of HFMD generally decreased in Tongzhou District, Beijing. The floating migrant population and children ≤5 years of age were at the highest risk of HFMD.

Autophagy induced by enterovirus 71 regulates the production of IL-6 through the p38MAPK and ERK signaling pathways

Enterovirus 71 (EV71) is the main causative agent of hand, foot, and mouth disease (HFMD), which has high morbidity and mortality. It mainly threatens children under six years of age. Because of a poor understanding of its pathogenesis, there are no effective drugs to control EV71 infection. Previous studies showed that EV71 infection induced autophagy and the production of cytokine IL-6. However, the underlying mechanisms between autophagy and the production of IL-6 induced by EV71 remain unclear. This study aimed to reveal the regulatory mechanisms between autophagy and the expression of IL-6 induced by EV71 infection. Our results showed that the proliferation of human gastric epithelial (GES-1) cells was inhibited by EV71 in a time- and dose-dependent manner. In addition, EV71 induced autophagy in GES-1 cells. EV71 infection promoted the expression and the release of IL-6 to the extracellular space, although the expression and release were inhibited by autophagy inhibitors 3-methyladenine (3-MA) and chloroquine (CQ) in GES-1 cells. The phosphorylated levels of p38MAPK and ERK proteins in GES-1 cells also increased after infection with EV71, and these changes were also reversed by 3-MA and CQ treatment. Our findings suggested that EV71-induced autophagy regulated the production of IL-6 through the p38MAPK and ERK signaling pathways.

Acute flaccid myelitis caused by enterovirus D68: Case definitions for use in clinical practice

Acute flaccid myelitis (AFM) was increasingly detected in recent years, coinciding with upsurges of enterovirus D68 (EV-D68) infections. We reviewed the evidence for a causal relationship between both. Based on reported cases, we provide case definitions for AFM caused by EV-D68 infections to enable a standard procedure for affected patients. Current case definitions are focussing on epidemiological aspects but clinical case definitions are still missing. We propose the following case definitions to be used in clinical practice in order to mirror clinical realities and facilitate a common systematic approach in case management: A possible case is defined as a person presenting with either acute myelitis/paralysis or Guillain-Barré Syndrome (GBS), particularly during periods of EV-D68 circulation. A probable case is defined as a person presenting with symptoms of either acute myelitis/paralysis or GBS and at least one of the following criteria: i) MRI abnormality representing with T2 hyperintensity in spinal cord grey matter with or without hyperintensity at dorsal brain stem, ii) investigations showing an axonal neuropathy including reduced compound motor action potentials with normal conduction velocities and absence of conduction blocks compatible with anterior horn cell disease or iii) detection of enteroviruses in a respiratory specimen obtained from the lower respiratory tract during periods of EV-D68 circulation. A confirmed case is defined as a person presenting with acute flaccid myelitis/paralysis, MRI abnormality and detection of enterovirus-D68-specific nucleic acids in a respiratory specimen using a validated PCR assay targeting the VP1 gene with subsequent sequencing and typing.

Identification and characterization of nonpolio enterovirus associated with nonpolio-acute flaccid paralysis in polio endemic state of Uttar Pradesh, Northern India

Despite polio eradication, nonpolio enterovirus (NPEV) detection amid polio surveillance, which is considered to have implications in paralysis, requires attention. The attributes of NPEV infections in nonpolio-AFP (NPAFP) cases from Uttar Pradesh (UP), India, remain undetermined and are thus investigated. A total of 1839 stool samples collected from patients with acute flaccid paralysis (AFP) from UP, India, between January 2010 and October 2011 were analyzed as per the WHO algorithm. A total of 359 NPAFP cases yielded NPEVs, which were subjected to microneutralization assay, partial VP1 gene-based molecular serotyping and phylogenetic analysis. Demographic and clinical-epidemiological features were also ascertained. Echoviruses (29%) and Coxsackievirus (CV)-B (17%) were the most common viruses identified by the microneutralization assay. The molecular genotyping characterized the NPEVs into 34 different serotypes, corresponding to Enterovirus (EV)-A (1.6%), EV-B (94%) and EV-C (5.3%) species. The rarely described EV serotypes, such as EV-C95, CV-A20, EV-C105, EV-B75, EV-B101, and EV-B107, were also identified. NPEV-associated AFP was more prevalent in younger male children, peaked in the monsoon months and was predominantly found in the central part of the state. The NPEV strains isolated in the study exhibited genetic diversity from those isolated in other countries. These form part of a different cluster or subcluster existing in cocirculation, limited to India only. This study augments the understanding of epidemiological features and demonstrates the extensive diversity exhibited by the NPEV strains in NPAFP cases from the polio-endemic region. It also underscores the need or effective long-term strategies to monitor NPEV circulation and its associated health risks in the post-polio eradication era.

Detection of central nervous system viral infections in adults in Manado, North Sulawesi, Indonesia

Central nervous system (CNS) viral infections are important causes of morbidity and mortality worldwide but the systematic survey of patients admitted to hospitals with CNS infections in many countries, including Indonesia, is limited. To obtain more information regarding the causes of CNS infections in Indonesia, this study was performed to detect and identify viral agents associated with CNS infections amongst in-patients at a referral hospital in Manado, North Sulawesi, Indonesia. Adult patients admitted to R.D. Kandou General Hospital with presumed CNS infection were enrolled. Cerebrospinal fluid, serum, and throat swab samples were collected and tested using molecular, serological, and virus isolation assays. A confirmed viral etiology was established in three and a probable/possible in 11 out of 74 patients. The most common was herpes simplex virus 1 (7/74, 9.5%), followed by Epstein-Barr virus (2/74, 2.7%), cytomegalovirus (1/74, 1.4%), enterovirus D68 (1/74, 1.4%), rhinovirus A (1/74, 1.4%), dengue virus (1/64, 1.6%), and Japanese encephalitis virus (1/64, 1.6%). There were 20 fatal cases (27.0%) during hospitalization in which eight were associated with viral causes. We identified herpes simplex virus 1 as the most common cause of CNS infection among adults in North Sulawesi with most of the cases remaining undiagnosed. Our study highlights the challenges in establishing the etiology of viral CNS infections and the importance of using a wide range of molecular and serological detection methods to identify CNS viruses.

Inflammatory profiles revealed the dysregulation of cytokines in adult patients of HFMD

BACKGROUND

Adult patients of HFMD might act as potential enterovirus reservoirs. As enterovirus infection will cause acute inflammatory response, identifying the association between the dysregulation of cytokines and the development and prognosis of HFMD in adult patients has vital clinical significance.

METHODS

60 patients from 266 laboratory-confirmed adult HFMD cases were included in this study, with 40 healthy adult subjects serving as the controls. Social-demographic data were collected through follow-up phone calls. Serum samples were collected from the participants. Enterovirus genotype was tested by RT-PCR, and the expression of cytokines were examined according to the manufacturer's instructions. Cases were classified using the cytokine profiles with machine learning algorithm.

RESULTS

Adult patients of HFMD presented with dysregulation of cytokines. 15 cytokines of adult patients were significantly elevated and 11 cytokines were decreased compared with those of controls. Correlation analysis showed some cytokines have positive correlation with the clinical characteristics and others have negative correlation. All of the enteroviral genotype presented cytokine dysregulation, and five cytokines were significantly different between genotypes. Using a random forest algorithm, we could classify the cytokine profiles into HFMD class and control class with a very high accuracy.

CONCLUSION

These findings suggested that cytokine expression was correlated with the enteroviral infection, genotype and clinical presentation. The inflammatory profiles could be developed as markers to identify HFMD cases with machine learning algorithm.

Safety, tolerability, and efficacy of fluoxetine as an antiviral for acute flaccid myelitis

OBJECTIVE

To determine the safety, tolerability, and efficacy of fluoxetine for proven or presumptive enterovirus (EV) D68-associated acute flaccid myelitis (AFM).

METHODS

A multicenter cohort study of US patients with AFM in 2015-2016 compared serious adverse events (SAEs), adverse effects, and outcomes between fluoxetine-treated patients and untreated controls. Fluoxetine was administered at the discretion of treating providers with data gathered retrospectively. The primary outcome was change in summative limb strength score (SLSS; sum of Medical Research Council strength in all 4 limbs, ranging from 20 [normal strength] to 0 [complete quadriparesis]) between initial examination and latest follow-up, with increased SLSS reflecting improvement and decreased SLSS reflecting worsened strength.

RESULTS

Fifty-six patients with AFM from 12 centers met study criteria. Among 30 patients exposed to fluoxetine, no SAEs were reported and adverse effect rates were similar to unexposed patients (47% vs 65%, p = 0.16). The 28 patients treated with >1 dose of fluoxetine were more likely to have EV-D68 identified (57.1% vs 14.3%, p < 0.001). Their SLSS was similar at initial examination (mean SLSS 12.9 vs 14.3, p = 0.31) but lower at nadir (mean SLSS 9.25 vs 12.82, p = 0.02) and latest follow-up (mean SLSS 12.5 vs 16.4, p = 0.005) compared with the 28 patients receiving 1 (n = 2) or no (n = 26) doses. In propensity-adjusted analysis, SLSS from initial examination to latest follow-up decreased by 0.2 (95% confidence interval [CI] -1.8 to +1.4) in fluoxetine-treated patients and increased by 2.5 (95% CI +0.7 to +4.4) in untreated patients (p = 0.015).

CONCLUSION

Fluoxetine was well-tolerated. Fluoxetine was preferentially given to patients with AFM with EV-D68 identified and more severe paralysis at nadir, who ultimately had poorer long-term outcomes.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that for patients with EV-D68-associated AFM, fluoxetine is well-tolerated and not associated with improved neurologic outcomes.

Nerve Transfers for Enterovirus D68-Associated Acute Flaccid Myelitis: A Case Series

BACKGROUND

Acute flaccid myelitis is associated with enterovirus D68 -induced inflammation and destruction of cervical anterior horn cells. To date, no medical intervention has altered the disease course.

METHODS

We report two pediatric patients who were treated with nerve transfer in three limbs with sustained upper extremity neuropathy. Postoperative outcomes included muscle strength, graded on the British Medical Research Council (BMRC) scale, range of motion, and electromyography.

RESULTS

Two years postoperatively, Patient 1 had improved elbow flexion to BMRC grade 4+, 125° of flexion, and discrete to decreased motor unit recruitment in targeted muscles. Twenty-one months postoperatively, Patient 2 demonstrated right brachialis flexion to BMRC grade 4+/5 and deltoid firing with simultaneous pectoralis major recruitment, and limited but active flexor digitorum profundus flexion.

CONCLUSIONS

Both patients continue to demonstrate functional recovery two years postoperatively. These outcomes suggest a promising reconstructive technique for this emerging and devastating viral endemic.

Epidemiological characteristics and influential factors of hand, foot, and mouth disease reinfection in Wuxi, China, 2008-2016

Background

Hand, foot, and mouth disease (HFMD) is a viral disease caused by human enteroviruses. Although HFMD reinfection is common, studies investigating this phenomenon are insufficient.

Methods

The present study focused on HFMD reinfection in Wuxi from 2008 to 2016 using surveillance system data.

Results

Of 107,677 cases included in the study, 6470 cases were classified as reinfections. The overall reinfection rate was 6.01% (6.37% male and 5.48% female patients), which decreased with increasing age (χ² = 1125.477, p < 0.001). The rate was 6.17 and 5.79% in urban and rural areas, respectively, and 7.83 and 5.98% of the cases were severe and mild, respectively. Multivariate logistic regression analysis showed that male sex, younger age, residence in an urban area, and severe disease were risk factors for HFMD reinfection. The case-severity rate in secondary infection cases was lower than that in non-reinfection cases (odds ratio 0.675, 95% confidence interval 0.526–0.866).

Conclusions

Boys younger than 4 years of age living in urban areas were more prone to reinfection. Specific health education and intervention should be developed to protect these susceptible populations.

A VP1 mutation acquired during an enterovirus 71 disseminated infection confers heparan sulfate binding ability and modulates ex vivo tropism

Enterovirus 71 (EV71) causes hand, foot and mouth disease, a mild and self-limited illness that is sometimes associated with severe neurological complications. EV71 neurotropic determinants remain ill-defined to date. We previously identified a mutation in the VP1 capsid protein (L97R) that was acquired over the course of a disseminated infection in an immunocompromised host. The mutation was absent in the respiratory tract but was present in the gut (as a mixed population) and in blood and cerebrospinal fluid (as a dominant species). In this study, we demonstrated that this mutation does not alter the dependence of EV71 on the human scavenger receptor class B2 (SCARB2), while it enables the virus to bind to the heparan sulfate (HS) attachment receptor and modifies viral tropism in cell lines and in respiratory, intestinal and neural tissues. Variants with VP197L or VP197R were able to replicate to high levels in intestinal and neural tissues and, to a lesser extent, in respiratory tissues, but their preferred entry site (from the luminal or basal tissue side) differed in respiratory and intestinal tissues and correlated with HS expression levels. These data account for the viral populations sequenced from the patient's respiratory and intestinal samples and suggest that improved dissemination, resulting from an acquired ability to bind HS, rather than specific neurotropism determinants, enabled the virus to reach and infect the central nervous system. Finally, we showed that iota-carrageenan, a highly sulfated polysaccharide, efficiently blocks the replication of HS-dependent variants in cells and 2D neural cultures. Overall, the results of this study emphasize the importance of HS binding in EV71 pathogenesis and open new avenues for the development of antiviral molecules that may prevent this virus's dissemination.

Enterovirus D68 and acute flaccid myelitis-evaluating the evidence for causality

Increased circulation of enterovirus D68 in 2014 and 2016 temporally and geographically coincided with increases in cases of acute flaccid myelitis, an uncommon condition of paralysis due to lesions in the anterior horn of the spinal cord. The identification of enterovirus D68 in respiratory specimens from cases of acute flaccid myelitis worldwide further supports an association, yet the absence of direct virus isolation from affected tissues, infrequent detection in cerebrospinal fluid, and the absence, until recently, of an animal model has left the causal nature of the relationship unproven. In this Personal View we evaluate epidemiological and biological evidence linking enterovirus D68 and acute flaccid myelitis. We applied the Bradford Hill criteria to investigate the evidence for a causal relationship and highlight the importance of comprehensive surveillance and research to further characterise the role of enterovirus D68 in acute flaccid myelitis and pursue effective therapies and prevention strategies.

Establishment and characterization of an oral gerbil model for a non-mouse-adapted enterovirus 71 strain

Enterovirus 71 (EV71) is one of the major pathogens causing hand, foot, and mouth disease (HFMD) with neurological and systemic complications worldwide, and it is mostly discovered in infants and young children. It is of great significance to establish suitable animal models of EV71 infection on research of distribution and pathogenesis of the virus. In this study, we established a successful infection of a non-mouse-adapted isolate of EV71 via oral route in 7-day-old Mongolian gerbil (Meriones unguiculatus), all of which were paralyzed and died within 10 days post infection. Analysis of virus loads in twelve tissues showed that virus was first detected in intestine, blood, heart, lung, and muscle one day post-infection, and then in the rest of the tissues/organs within the next few days, among which thymus, spleen, spinal cord and muscles had the highest virus titer at 5 days post infection. Pathological examination showed that severe necrosis was observed in skeletal muscle and spinal cord, and edema was observed in both heart and lung. Comparisons of host gene expression of various tissues from infected and non-infected gerbils revealed a general up-regulation of genes related to anti-viral response and a viral receptor gene (sialic acid-linked glycans), as well as a tissue(gut)-specific up-regulation of genes related to neuronal communication. Collectively, our results showed that EV71 could induce severe neurological complications as well as massive tissue damage all over the body, which indicates that oral infection of 7-day gerbils can be a suitable animal model to study the infection of EV71 in human.

Acute Flaccid Paralysis and Enteroviral Infections

PURPOSE OF REVIEW

The focus of this review is on enterovirus (EV)-associated acute flaccid paralysis (AFP) due to spinal cord anterior horn cell disease. Emphasis is placed on the epidemiology, pathogenesis, diagnosis, treatment, and outcome of AFP caused by polioviruses, vaccine-derived polioviruses, EV-D68, and EV-A71.

RECENT FINDINGS

Since the launch of The Global Polio Eradication Initiative in 1988, the worldwide incidence of polio has been reduced by 99.9%, with small numbers of poliomyelitis cases being reported only in Afghanistan, Pakistan, and Nigeria. With the planned phaseout of oral polio vaccine, vaccine-associated poliomyelitis is also expected to be eliminated. In their place, other EVs, chiefly EV-D68 and EV-A71, have emerged as the principal causes of AFP. There is evidence that the emergence of EV-D68 as a cause of severe respiratory disease and AFP was due to recent genetic virus evolution. Antiviral medications targeting EV-D68, EV-A71, and other EVs will likely be available in the near future. An effective EV-A71 vaccine has been developed, and preliminary investigations suggest an EV-D68 vaccine could be on the horizon. The eradication of poliomyelitis and vaccine-associated poliomyelitis is near, after which other EVs, presently EV-D68 and EV-A71, will be the principle viral causes of AFP. Moving forward, it is essential that EV outbreaks, in particular those associated with neurologic complications, be investigated carefully and the causal strains identified, so that treatment and prevention efforts can be rapidly developed and implemented.

Mutations in VP1 and 5'-UTR affect enterovirus 71 virulence

Enterovirus 71 (EV71) is a major cause of hand, foot and mouth disease (HFMD). The current EV71 propagating in Vero (EV-V) or sub-passaged in RD (EV-R) cells was used as a pathogen. Interestingly, EV-R exhibited differential virulence; challenging human scavenger receptor class B2-expressing (hSCARB2-Tg) mice with EV71 revealed that EV-V was more virulent than EV-R: 100% of mice that received lethal amounts of EV-V died, while all the mice that received EV-R survived. Severe pathogenesis correlated with viral burdens and proinflammatory cytokine levels were observed in EV-V-challenged mice, but controversy in EV-R-challenged mice. Consensus sequence analysis revealed EV-R rapidly acquired complete mutations at E145G and S241L and partial mutations at V146I of VP1, and acquired a T to C substitution at nucleotide 494 of the 5'-UTR. EV-R exhibited higher binding affinity for another EV71 receptor, human P-selectin glycoprotein ligand-1 (hPSGL-1), than EV-V. Both EV71s exhibited no significant difference in binding to hSCARB2. The molecular modelling indicate that these mutations might influence EV71 engagement with PSGL-1 and in vivo virulence.