Association of Enterovirus D68 with Acute Flaccid Myelitis, Philadelphia, Pennsylvania, USA, 2009-2018

Predicting the impact of COVID-19 non-pharmaceutical intervention on short- and medium-term dynamics of enterovirus D68 in the US

Recent outbreaks of enterovirus D68 (EV-D68) infections, and their causal linkage with acute flaccid myelitis (AFM), continue to pose a serious public health concern. During 2020 and 2021, the dynamics of EV-D68 and other pathogens have been significantly perturbed by non-pharmaceutical interventions against COVID-19; this perturbation presents a powerful natural experiment for exploring the dynamics of these endemic infections. In this study, we analyzed publicly available data on EV-D68 infections, originally collected through the New Vaccine Surveillance Network, to predict their short- and long-term dynamics following the COVID-19 interventions. Although long-term predictions are sensitive to our assumptions about underlying dynamics and changes in contact rates during the NPI periods, the likelihood of a large outbreak in 2023 appears to be low. Comprehensive surveillance data are needed to accurately characterize future dynamics of EV-D68. The limited incidence of AFM cases in 2022, despite large EV-D68 outbreaks, poses further questions for the timing of the next AFM outbreaks.

Licochalcone A regulates viral IRES activity to inhibit enterovirus replication

Enterovirus D68 (EV-D68), belonging to the genus Enterovirus of the Picornavirus family, is an emerging pathogen that can cause neurological and respiratory diseases in children. However, there is little understanding of the pathogenesis of EV-D68, and no effective vaccine or drug for the prevention or treatment of the diseases caused by this virus is available. Autophagy is a cellular process that targets cytoplasmic proteins or organelles to the lysosomes for degradation. Enteroviruses strategically harness the host autophagy pathway to facilitate the completion of their life cycle. Therefore, we selected an autophagy compound library to screen for autophagy-related compounds that may affect viral growth. By using the neutralization screening assay, we identified a compound, 'licochalcone A' that significantly inhibited EV-D68 replication. To investigate the mechanism by which licochalcone A inhibits EV-D68 replication and to identify the viral life cycle stage it inhibits, the time-of-addition, viral attachment, viral entry, and dual-luciferase reporter assays were performed. The results of the time-of-addition assay showed that licochalcone A, a characteristic chalcone found in liquorice roots and widely used in traditional Chinese medicine, inhibits EV-D68 replication during the early stages of the viral life cycle, while those of the dual-luciferase reporter assay showed that licochalcone A does not regulate viral attachment and entry, but inhibits EV-D68 IRES-dependent translation. Licochalcone A also inhibited enterovirus A71 and coxsackievirus B3 but did not significantly inhibit dengue virus 2 or human coronavirus 229E replication. Licochalcone A regulates IRES translation to inhibit EV-D68 viral replication.

Enterovirus characterized from cerebrospinal fluid in a cohort from the Eastern United States

BACKGROUND

Enteroviruses (EVs) are predominant causes of a spectrum of neurological diseases. To better understand the origins of the outbreaks of disease associated with EV, it is essential to develop an efficient surveillance system that identifies the circulating EVs and correlate their genomic evolution with the disease presentations.

METHODS

The clinical presentations of patients with positive EV from cerebrospinal fluid (CSF) between 2014 and 2022, diagnosed at the Johns Hopkins Medical Microbiology Laboratory, were compared from year to year. EV typing and whole genome sequencing were performed and correlated to the spectrum of disease.

RESULTS

A total of 95 CSF specimens were positive for EV between 2014 and 2022. The percentage positivity ranged from the lowest of 1.1% in 2020 to the highest of 3.2% in 2015. The median ages declined from 22 years in 2014 to less than one year starting in 2016 to 34 in 2022. Typing using VP1 sequencing revealed that E30 and E6 were associated with meningitis in adults but coxsackieviruses (CVs-B3 and B5) were detected from pediatric patients with fever. Whole genome sequencing revealed multiple recombination events. In 2020, a recombinant CV-A9 was detected in a CSF sample associated with unusual presentation of sepsis, profound acute bilateral sensory neural hearing loss, and myofasciitis.

CONCLUSIONS

EV genomic surveillance is needed for a better understanding of the genetic determinants of neurovirulence. Whole genome sequencing can reveal recombination events missed by traditional molecular surveillance methods.

RNA Structure in the 5' Untranslated Region of Enterovirus D68 Strains with Differing Neurovirulence Phenotypes

Enterovirus-D68 (EV-D68) is a positive-sense single-stranded RNA virus within the family Picornaviridae. EV-D68 was initially considered a respiratory virus that primarily affected children. However, in 2014, EV-D68 outbreaks occurred causing the expected increase in respiratory illness cases, but also an increase in acute flaccid myelitis cases (AFM). Sequencing of 2014 outbreak isolates revealed variations in the 5' UTR of the genome compared to the historical Fermon strain. The structure of the 5' UTR RNA contributes to enterovirus virulence, including neurovirulence in poliovirus, and could contribute to neurovirulence in contemporary EV-D68 strains. In this study, the secondary and tertiary structures of 5' UTR RNA from the Fermon strain and 2014 isolate KT347251.1 are analyzed and compared. Secondary structures were determined using SHAPE-MaP and TurboFold II and tertiary structures were predicted using 3dRNAv2.0. Comparison of RNA structures between the EV-D68 strains shows significant remodeling at the secondary and tertiary levels. Notable secondary structure changes occurred in domains II, IV and V. Shifts in the secondary structure changed the tertiary structure of the individual domains and the orientation of the domains. Our comparative structural models for EV-D68 5' UTR RNA highlight regions of the molecule that could be targeted for treatment of neurotropic enteroviruses.

Acute Flaccid Myelitis: Review of Clinical Features, Diagnosis, and Management with Nerve Transfers

BACKGROUND

Acute flaccid myelitis (AFM) is a devastating neurologic condition in children, manifesting as acute limb weakness and/or paralysis. Despite increased awareness of AFM following initiation of U.S. surveillance in 2014, no treatment consensus exists. The purpose of this systematic review was to summarize the most current knowledge regarding AFM epidemiology, cause, clinical features, diagnosis, and supportive and operative management, including nerve transfer.

METHODS

The authors systematically reviewed the literature based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using multiple databases to search the keywords ("acute flaccid myelitis"), ('acute flaccid myelitis'/exp OR 'acute flaccid myelitis'), and (Acute AND flaccid AND myelitis). Included articles reported on (1) AFM diagnosis and (2) patient-specific data regarding epidemiology, cause, clinical features, diagnostic features, or management of AFM.

RESULTS

Ninety-nine articles were included in this review. The precise cause and pathophysiologic mechanism of AFM remain undetermined, but AFM is strongly associated with nonpolio enterovirus infections. Clinical presentation typically comprises preceding viral prodrome, pleocytosis, spinal cord lesions on T2-weighted magnetic resonance imaging, and acute onset of flaccid weakness/paralysis with hyporeflexia in at least one extremity. Supportive care includes medical therapy and rehabilitation. Early studies of nerve transfer for AFM have shown favorable outcomes for patients with persistent weakness.

CONCLUSIONS

Supportive care and physical therapy are the foundation of a multidisciplinary approach to managing AFM. For patients with persistent limb weakness, nerve transfer has shown promise for improving function in distal muscle groups. Surgeons must consider potential spontaneous recovery, patient selection, donor nerve availability, recipient nerve appropriateness, and procedure timing.

Circulation of enterovirus D68 (EV-D68) causing respiratory illness in New South Wales, Australia, between August 2018 and November 2019

The incidence of enterovirus D68 (EV-D68) in New South Wales, Australia, is unknown. As part of a state-wide surveillance program, enterovirus positive diagnostic specimens were assessed from patients presenting to hospitals with respiratory and meningitis syndromes from August 2018 to November 2019. Diagnostic enterovirus positive samples were collected from 339 patients and re-extracted followed by targeted PCR across the whole EV-D68 genome (7.4 kb). Obtained amplicons (n=208) were sequenced using Illumina sequencing technology and the phylogenetic relationships analysed relative to EV-D68 Fermon strain. We identified EV-D68 in 31 patients, both children (n=27) and adults (n=4). Phylogenetically, the majority (n=30) were from subclade B3, the same as that causing outbreaks of EV-D68 across the USA and Europe during 2018. These data strengthen the importance of having an active enterovirus surveillance network.

Evolution, geographic spreading, and demographic distribution of Enterovirus D68

Worldwide outbreaks of enterovirus D68 (EV-D68) in 2014 and 2016 have caused serious respiratory and neurological disease. We collected samples from several European countries during the 2018 outbreak and determined 53 near full-length genome (‘whole genome’) sequences. These sequences were combined with 718 whole genome and 1,987 VP1-gene publicly available sequences. In 2018, circulating strains clustered into multiple subgroups in the B3 and A2 subclades, with different phylogenetic origins. Clusters in subclade B3 emerged from strains circulating primarily in the US and Europe in 2016, though some had deeper roots linking to Asian strains, while clusters in A2 traced back to strains detected in East Asia in 2015-2016. In 2018, all sequences from the USA formed a distinct subgroup, containing only three non-US samples. Alongside the varied origins of seasonal strains, we found that diversification of these variants begins up to 18 months prior to the first diagnostic detection during a EV-D68 season. EV-D68 displays strong signs of continuous antigenic evolution and all 2018 A2 strains had novel patterns in the putative neutralizing epitopes in the BC- and DE-loops. The pattern in the BC-loop of the USA B3 subgroup had not been detected on that continent before. Patients with EV-D68 in subclade A2 were significantly older than patients with a B3 subclade virus. In contrast to other subclades, the age distribution of A2 is distinctly bimodal and was found primarily among children and in the elderly. We hypothesize that EV-D68’s rapid evolution of surface proteins, extensive diversity, and high rate of geographic mixing could be explained by substantial reinfection of adults. Better understanding of evolution and immunity across diverse viral pathogens, including EV-D68 and SARS-CoV-2, is critical to pandemic preparedness in the future.

Enterovirus D68 (EV-D68) has caused punctuated, global outbreaks of respiratory illness and neurological disease, including being implicated as the cause of acute flaccid myelitis (AFM). Serology studies and surveillance data suggests almost everyone is infected during early childhood. The majority of sequences collected are from young children, while adults retain high antibody titers against strains that circulated when they were young. However, little is known about how outbreaks are connected and how the virus evolves and spreads around the globe. Despite EV-D68’s apparent reliance on young, naive hosts, EV-D68 antibody binding sites are reportedly evolving under antigenic pressure, and EV-D68 seems to spread rapidly during outbreaks. In this multi-center European collaboration, we confirm that subclade specific age differences are present in those infected. Further, we were able to quantify between- and within-country migration and the ‘hidden’ diversification that indicates unsampled circulation between outbreaks. We conclude that the evolution of EV-D68 may be driven by substantial re-infection of adults, explaining the rapid geographic mixing and continuous antigenic evolution. The presence of largely unsampled circulation prior to outbreaks suggests there are gaps in current surveillance practices which could be addressed by expanding genetic surveillance.

Global prevalence and case fatality rate of Enterovirus D68 infections, a systematic review and meta-analysis

A substantial amount of epidemiological data has been reported on Enterovirus D68 (EV-D68) infections after the 2014 outbreak. Our goal was to map the case fatality rate (CFR) and prevalence of current and past EV-D68 infections. We conducted a systematic review (PROSPERO, CRD42021229255) with published articles on EV-68 infections in PubMed, Embase, Web of Science and Global Index Medicus up to January 2021. We determined prevalences using a model random effect. Of the 4,329 articles retrieved from the databases, 89 studies that met the inclusion criteria were from 39 different countries with apparently healthy individuals and patients with acute respiratory infections, acute flaccid myelitis and asthma-related diseases. The CFR estimate revealed occasional deaths (7/1353) related to EV-D68 infections in patients with severe acute respiratory infections. Analyses showed that the combined prevalence of current and past EV-D68 infections was 4% (95% CI = 3.1–5.0) and 66.3% (95% CI = 40.0–88.2), respectively. The highest prevalences were in hospital outbreaks, developed countries, children under 5, after 2014, and in patients with acute flaccid myelitis and asthma-related diseases. The present study shows sporadic deaths linked to severe respiratory EV-D68 infections. The study also highlights a low prevalence of current EV-D68 infections as opposed to the existence of EV-D68 antibodies in almost all participants of the included studies. These findings therefore highlight the need to implement and/or strengthen continuous surveillance of EV-D68 infections in hospitals and in the community for the anticipation of the response to future epidemics.

Enterovirus D68 (EV-D68) infections represent a global public health concern. EV-D68 are detected in apparently healthy subjects and patients with acute respiratory illnesses, acute flaccid myelitis, and asthma-related illnesses. Enterovirus D68 was first described in 1962 and exhibited sporadic circulation until August 2014 when outbreaks of EV-D68 infections were reported in the USA and Canada mainly in children with acute flaccid myelitis and severe acute respiratory disease. We systematically reviewed the literature on EV-D68 infections globally in the present study to determine the case fatality rate and prevalence of current and past infections. Our results show sporadic deaths in patients with severe acute respiratory EV-D68 infections. Our data also show a low prevalence of EV-D68 in current infections unlike the presence of EV-D68 antibodies (past infections) in almost all individuals of all ages. EV-D68 infections were more prevalent in hospital outbreaks, industrialized countries, children < 5 years, and patients with acute flaccid myelitis and asthma-related diseases. These data highlight the need to strengthen the surveillance of EV-D68 infections.

An Overview of Acute Flaccid Myelitis

Acute Flaccid Myelitis is defined by the presence of Acute Flaccid Paralysis (AFP) and a spinal cord lesion on magnetic resonance imaging that is primarily limited to the grey matter. AFM is a difficult situation to deal with when you have a neurologic illness. According to the Centers for Disease Control and Prevention (CDC), a large number of cases were discovered in the United States in 2014, with 90% of cases occurring in children. Although the exact cause of AFM is unknown, mounting evidence suggests a link between AFM and enterovirus D68 (EV-D68). In 2014, an outbreak of AFM was discovered in the United States. The condition was initially linked to polioviruses; however, it was later found that the viruses were caused by non-polioviruses Enteroviruses D-68 (EV-D68). The number of cases has increased since 2014, and the disease has been declared pandemic in the United States. The sudden onset of muscle weakness, usually in an arm or leg, as well as pain throughout the body, the change in patient's facial expression (facial weakness), and shortness of breath, ingesting, and speaking are all common symptoms in patients suffering from neurologic disease. This article includes graphic and histogram representations of reported AFM incidents and criteria for causality, epidemiology, various diagnostic approaches, signs and symptoms, and various investigational guidelines. It also includes key statements about recent clinical findings related to AFM disease.

Infection-Related Myelopathies

Recent years have seen growing attention to inflammatory and infectious disorders of the spinal cord, not only due to the discovery of autoantibody-mediated disorders of the spinal cord [e.g., aquaporin-4 immunoglobulin G (IgG) antibodies and myelin oligodendrocyte glycoprotein IgG antibodies], but also due to the emergence of clusters of infection-related myelopathy, now known as acute flaccid myelitis. We review the spectrum of infection-related myelopathies and outline a nosological classification system based on association with infection. We describe the epidemiology and definitions of myelopathies, with a discussion of clinical presentation and neuroimaging features, and then turn to specific discussion of myelopathies due to direct pathogen invasion and those considered to be post- or parainfectious. Expected final online publication date for the Annual Review of Pathology: Mechanisms of Disease, Volume 17 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Comparative analysis of the molecular mechanism of resistance to vapendavir across a panel of picornavirus species

Vapendavir is a rhino/enterovirus inhibitor that targets a hydrophobic pocket in the viral capsid preventing the virus from entering the cell. We set out to study and compare the molecular mechanisms of resistance to vapendavir among clinically relevant Picornavirus species. To this end in vitro resistance selection of drug-resistant isolates was applied in rhinovirus 2 and 14, enterovirus-D68 and Poliovirus 1 Sabin. Mutations in the drug-binding pocket in VP1 (C199R/Y in hRV14; I194F in PV1; M252L and A156T in EV-D68), typical for this class of compounds, were identified.

Interestingly, we also observed mutations located outside the pocket (K167E in EV-D68 and G149C in hRV2) that contribute to the resistant phenotype. Remarkably, the G149C substitution rendered the replication of human rhinovirus 2 dependent on the presence of vapendavir. Our data suggest that the binding of vapendavir to the capsid of the G149C isolate may be required to stabilize the viral particle and to allow efficient dissemination of the virus. We observed the dependency of the G149C isolate on other compounds of this class, suggesting that this phenotype is common for capsid binders. In addition the VP1 region containing the G149C substitution has not been associated with antiviral resistance before. Our results demonstrate that the phenotype and genotype of clinically relevant vapendavir-resistant picornavirus species is more complex than generally believed.

The role of conformational epitopes in the evolutionary divergence of enterovirus D68 clades: A bioinformatics-based study

Enterovirus D68 (EV-D68), as one of the major pathogens of paediatric respiratory disease, has been widely spread in the population in recent years. As the basis of virus antigenicity, antigenic epitopes are essential to monitoring the transformation of virus antigenicity. However, there is a lack of systematic studies on the antigenic epitopes of EV-D68. In this study, a bioinformatics-based prediction algorithm for human enteroviruses was used to predict the conformational epitopes of EV-D68. The prediction results showed that the conformational epitopes of EV-D68 were clustered into three sites: site 1, site 2, and site 3. Site 1 was located in the "north rim" region of the canyon near the fivefold axis; site 2 was located in the "puff" region near the twofold axis; and site 3 consisted of two parts, one in the "knob" region on the south rim of the canyon and the other in the threefold axis region. The predicted epitopes overlapped highly with the binding regions of four reported monoclonal antibodies (mAbs), indicating that the predictions were highly reliable. Phylogenetic analysis showed that amino acid mutations in the epitopes of the VP1 BC loop, DE loop, C-terminus, and VP2 EF loop played a crucial role in the evolutionary divergence of EV-D68 clades/subclades and epidemics. This finding indicated that the VP1 BC loop, DE loop, C-terminus, and VP2 EF loop were the most important epitopes of EV-D68. Research on the epitopes of EV-D68 will contribute to outbreak surveillance and to the development of diagnostic reagents and recombinant vaccines.

Epidemiological dynamics of enterovirus D68 in the United States and implications for acute flaccid myelitis

Acute flaccid myelitis (AFM) recently emerged in the United States as a rare but serious neurological condition since 2012. Enterovirus D68 (EV-D68) is thought to be a main causative agent, but limited surveillance of EV-D68 in the United States has hampered the ability to assess their causal relationship. Using surveillance data from the BioFire Syndromic Trends epidemiology network in the United States from January 2014 to September 2019, we characterized the epidemiological dynamics of EV-D68 and found latitudinal gradient in the mean timing of EV-D68 cases, which are likely climate driven. We also demonstrated a strong spatiotemporal association of EV-D68 with AFM. Mathematical modeling suggested that the recent dominant biennial cycles of EV-D68 dynamics may not be stable. Nonetheless, we predicted that a major EV-D68 outbreak, and hence an AFM outbreak, would have still been possible in 2020 under normal epidemiological conditions. Nonpharmaceutical intervention efforts due to the ongoing COVID-19 pandemic are likely to have reduced the sizes of EV-D68 and AFM outbreaks in 2020, illustrating the broader epidemiological impact of the pandemic.

Non-Polio Enteroviruses from Acute Flaccid Paralysis Surveillance in Korea, 2012-2019

The risk of polio importation and re-emergence persists since epidemic polio still occurs in some countries, and the resurgence of polio occurring almost 20 years after polio eradication was declared in Asia has been reported. We analyzed the results of acute flaccid paralysis (AFP) surveillance in Korea to assess the quality of AFP surveillance and understand the etiology of non-polio enterovirus (NPEV)-associated central nervous system diseases in a polio-free area. We investigated 637 AFP patients under 15 years of age whose cases were confirmed during 2012–2019 by virus isolation, real-time reverse transcription polymerase chain reaction, and VP1 gene sequencing. Among the 637 AFP cases, NPEV was detected in 213 (33.4%) patients, with the majority observed in EV-A71, with 54.9% of NPEV positives. EV-A71 has been shown to play a role as a major causative agent in most neurological diseases except for Guillain-Barré syndrome (GBS), acute disseminated encephalomyelitis (ADEM), and meningitis. This study provides information on the AFP surveillance situation in Korea and highlights the polio eradication stage in the monitoring and characterization of NPEV against the outbreak of neurological infectious diseases such as polio.

Don't Forget the Flu - Determining the Etiology of Infective Myositis in a Child: A Case Report

Introduction

Infective myositis is an acute, self-limited condition, rarely occurring in children with recent viral infections. The condition is often overlooked by emergency physicians when endeavoring to exclude other diagnoses included in the differential. Diagnosis of the condition can be difficult when based purely on clinical presentation because it shares symptoms with much more concerning neurological illnesses. A few simple laboratory tests are indicated to reach the correct diagnosis.

Case Report

The following case report describes a three-year-old female diagnosed with a recent upper respiratory tract infection presenting to the emergency department with complaints of fatigue and inability to walk. She was diagnosed with an influenza-like illness three days prior by her pediatrician, the symptoms of which had mostly resolved by the time of presentation.

Conclusion

Muscle weakness and abnormal, uncoordinated gait with an acute upper respiratory tract infection in a child may be cause for concern, prompting unnecessary work-up. Emergency physicians should be aware of the signs and symptoms of influenza-associated infective myositis in children, especially during influenza season.

Epidemiological dynamics of enterovirus D68 in the US: implications for acute flaccid myelitis

The lack of active surveillance for enterovirus D68 (EV-D68) in the US has hampered the ability to assess the relationship with predominantly biennial epidemics of acute flaccid myelitis (AFM), a rare but serious neurological condition. Using novel surveillance data from the BioFire® Syndromic Trends (Trend) epidemiology network, we characterize the epidemiological dynamics of EV-D68 and demonstrate strong spatiotemporal association with AFM. Although the recent dominant biennial cycles of EV-D68 dynamics may not be stable, we show that a major EV-D68 epidemic, and hence an AFM outbreak, would still be possible in 2020 under normal epidemiological conditions. Significant social distancing due to the ongoing COVID-19 pandemic could reduce the size of an EV-D68 epidemic in 2020, illustrating the potential broader epidemiological impact of the pandemic.

Acute flaccid myelitis: cause, diagnosis, and management

Acute flaccid myelitis (AFM) is a disabling, polio-like illness mainly affecting children. Outbreaks of AFM have occurred across multiple global regions since 2012, and the disease appears to be caused by non-polio enterovirus infection, posing a major public health challenge. The clinical presentation of flaccid and often profound muscle weakness (which can invoke respiratory failure and other critical complications) can mimic several other acute neurological illnesses. There is no single sensitive and specific test for AFM, and the diagnosis relies on identification of several important clinical, neuroimaging, and cerebrospinal fluid characteristics. Following the acute phase of AFM, patients typically have substantial residual disability and unique long-term rehabilitation needs. In this Review we describe the epidemiology, clinical features, course, and outcomes of AFM to help to guide diagnosis, management, and rehabilitation. Future research directions include further studies evaluating host and pathogen factors, including investigations into genetic, viral, and immunological features of affected patients, host-virus interactions, and investigations of targeted therapeutic approaches to improve the long-term outcomes in this population.

Characteristics of Patients with Acute Flaccid Myelitis, United States, 2015-2018

Differences between years with and without increased activity suggest differences in viral etiologies.

Observed peaks of acute flaccid myelitis (AFM) cases have occurred biennially since 2014 in the United States. We aimed to determine if AFM etiology differed between peak and nonpeak years, considering that clinical features of AFM differ by virus etiology. We compared clinical and laboratory characteristics of AFM cases that occurred during peak (2016 and 2018, n = 366) and nonpeak (2015 and 2017, n = 50) years. AFM patients in peak years were younger (5.2 years) than those in nonpeak years (8.3 years). A higher percentage of patients in peak years than nonpeak years had pleocytosis (86% vs. 60%), upper extremity involvement (33% vs. 16%), and an illness preceding limb weakness (90% vs. 62%) and were positive for enterovirus or rhinovirus RNA (38% vs. 16%). Enterovirus D68 infection was associated with AFM only in peak years. Our findings suggest AFM etiology differs between peak and nonpeak years.

Association of outcomes in acute flaccid myelitis with identification of enterovirus at presentation: a Canadian, nationwide, longitudinal study

BACKGROUND

Acute flaccid myelitis (AFM) is characterised by rapid onset of limb weakness with spinal cord grey-matter abnormalities on MRI scan. We aimed to assess whether detection of enterovirus in respiratory or other specimens can help predict prognosis in children with AFM.

METHODS

In this nationwide, longitudinal study, we evaluated the significance of detection of enterovirus in any sample in predicting outcomes in a cohort of Canadian children younger than 18 years presenting with AFM to tertiary paediatric hospitals in Canada in 2014 and 2018. All patients fulfilled the 2015 US Centers for Disease Control and Prevention case definition for definite AFM or probable AFM. Clinical data, laboratory findings, treatment, and neuroimaging results were collected (follow up period up to 5 years). We assessed neurological function and motor outcomes using Kurtzke's Expanded Disability Status Scale (EDSS) and a Weakest Limb Score.

FINDINGS

58 children with AFM (median age 5·1 years, IQR 3·8-8·3) were identified across five of Canada's ten provinces and three territories. 25 (43%) children had enterovirus detected in at least one specimen: 16 (64%) with EV-D68, two (8%) with EV-A71, two (8%) with coxsackievirus, 10 (40%) with untyped enterovirus. Children who were enterovirus positive were more likely than those that were negative to have had quadriparesis (12 [48%] of 25 vs four [13%] of 30; p=0·028), bulbar weakness (11 [44%] of 25 vs two [7%] of 30; p=0·028), bowel or bladder dysfunction (14 [56%] of 25 vs seven [23%] of 30; p=0·040), cardiovascular instability (nine [36%] of 25 vs one [3%] of 30; p=0·028), and were more likely to require intensive care unit admission (13 [52%] of 25 vs 5 [17%] of 30; p=0·028). On MRI, most children who were enterovirus positive showed brainstem pontine lesions (14 [61%] of 23), while other MRI parameters did not correlate with enterovirus status. Median EDSS of enterovirus positive (EV+) and enterovirus negative (EV-) groups was significantly different at all timepoints: baseline (EDSS 8·5, IQR 4·1-9·5 vs EDSS 4·0, IQR 3·0-6·0; p=0·0067), 3 months (EDSS 4·0, IQR 3·0-7·4 vs EDSS 3·0, IQR 1·5-4·3; p=0·0067), 6 months (EDSS 3·5, IQR 3·0-7·0 vs EDSS 3·0, IQR 1·0-4·0; p=0·029), and 12 months (EDSS 3·0, IQR 3·0-6·9 vs EDSS 2·5 IQR 0·3-3·0; p=0·0067). Kaplan-Meier survival analysis of a subgroup of patients showed significantly poorer motor recovery among children who tested positive for enterovirus than for those who tested negative (p=0·037).

INTERPRETATION

Detection of enterovirus in specimens from non-sterile sites at presentation correlated with more severe acute motor weakness, worse overall outcomes and poorer trajectory for motor recovery. These results have implications for rehabilitation planning as well as counselling of families of children with these disorders. The findings of this study support the need for early testing for enterovirus in non-CNS sites in all cases of AFM.

FUNDING

None.

Cell culture demonstrates superior sensitivity over one step real time RT PCR and nested VP1 amplification for Enteroviruses

This study evaluated and compared the sensitivity profile of routine cell culture, nested VP1 amplification and one step real time RT PCR for Enteroviruses. Serially diluted spiked samples of four model viruses (EV71, CVA16, CVB5 and PV1) and 32 true positive samples including Poliovirus (PV1 & PV3), Coxsackie virus (CVB5, CVB3, CVB1 & CVA4, 10, 16), Echovirus (Echo 6, 7, 11, 13, 18, 25 & 30) and Enterovirus 71 (E71), and 32 true negative stool samples were subjected to cell culture, nested RT PCR and one step real time RT PCR. The result of sensitivity test indicated superior sensitivity with one step real time RT PCR (75 %, 24/32) against cell culture (71.9 %, 23/32) and nested RT PCR (65.6 %, 21/32). The most specific test was cell culture (100 %, 32/32), followed by nested RT PCR (96.9 %, 31/32). Positive predictive values were 100 %: 23/23, 95.5 %; 21/22 and 88.9 %; 24/27, for cell culture, nested RT PCR and one step real time RT PCR, respectively, and one step real time RT PCR had the highest negative predictive value (78.4 %, 29/37). Overall result indicate relatively high analytical sensitivity with all the tests, suggesting superior performance by cell culture. Therefore, cell culture is the gold standard. However, considering intensive nature of cell cultures and prolong window for results, it is wise to consider one step real time RT PCR in routine diagnosis for its added advantages. Meanwhile, selecting a combination of tests can maximize detection, depending on the laboratory strength.

Co-circulation of multiple enterovirus D68 subclades, including a novel B3 cluster, across Europe in a season of expected low prevalence, 2019/20

Enterovirus D68 (EV-D68) was detected in 93 patients from five European countries between 1 January 2019 and 15 January 2020, a season with expected low circulation. Patients were primarily children (n = 67, median age: 4 years), 59 patients required hospitalisation and five had severe neurologic manifestations. Phylogenetic analysis revealed two clusters in the B3 subclade and subclade A2/D. This circulation of EV-D68 associated with neurological manifestations stresses the importance of surveillance and diagnostics beyond expected peak years.

Biennial Upsurge and Molecular Epidemiology of Enterovirus D68 Infection in New York, USA, 2014 to 2018

Enterovirus D68 (EV-D68) infection has been associated with outbreaks of severe respiratory illness and increased cases of nonpolio acute flaccid myelitis. The patterns of EV-D68 circulation and molecular epidemiology are not fully understood. In this study, nasopharyngeal (NP) specimens collected from patients in the Lower Hudson Valley, New York, from 2014 to 2018 were examined for rhinovirus/enterovirus (RhV/EV) by the FilmArray respiratory panel. Selected RhV/EV-positive NP specimens were analyzed using two EV-D68-specific real-time RT-PCR assays, Sanger sequencing and metatranscriptomic next-generation sequencing. A total of 2,398 NP specimens were examined. EV-D68 was detected in 348 patients with NP specimens collected in 2014 (n = 94), 2015 (n = 0), 2016 (n = 160), 2017 (n = 5), and 2018 (n = 89), demonstrating a biennial upsurge of EV-D68 infection in the study area. Ninety-one complete or nearly complete EV-D68 genome sequences were obtained. Genomic analysis of these EV-D68 strains revealed dynamics and evolution of circulating EV-D68 strains since 2014. The dominant EV-D68 strains causing the 2014 outbreak belonged to subclade B1, with a few belonging to subclade B2. New EV-D68 subclade B3 strains emerged in 2016 and continued in circulation in 2018. Clade D strains that are rarely detected in the United States also arose and spread in 2018. The establishment of distinct viral strains and their variable circulation patterns provide essential information for future surveillance, diagnosis, vaccine development, and prediction of EV-D68-associated disease prevalence and potential outbreaks.

Vital Signs: Clinical Characteristics of Patients with Confirmed Acute Flaccid Myelitis, United States, 2018

Background

Acute flaccid myelitis (AFM) is a serious neurologic syndrome that affects mostly children and is characterized by the acute onset of limb weakness or paralysis. Since U.S. surveillance for AFM began in 2014, reported cases have peaked biennially. This report describes the clinical characteristics of AFM patients during 2018, the most recent peak year.

Methods

Medical records from persons meeting AFM clinical criterion (acute onset of flaccid limb weakness) were submitted to CDC. Patients with confirmed AFM met the clinical criterion and had magnetic resonance imaging indicating spinal cord lesions largely restricted to gray matter and spanning one or more vertebral segments. Symptoms, physical findings, test and imaging results, and hospitalization data were abstracted and described.

Results

Among 238 patients with confirmed AFM during 2018, median age was 5.3 years. Among the 238 patients, 205 (86%) had onset during August–November. Most (92%) had prodromal fever, respiratory illness, or both beginning a median of 6 days before weakness onset. In addition to weakness, common symptoms at clinical evaluation were gait difficulty (52%), neck or back pain (47%), fever (35%), and limb pain (34%). Among 211 who were outpatients when weakness began, most (76%) sought medical care within 1 day, and 64% first sought treatment at an emergency department. Overall, 98% of patients were hospitalized, 54% were admitted to an intensive care unit, and 23% required endotracheal intubation and mechanical ventilation.

Conclusion

Clinicians should suspect AFM in children with acute flaccid limb weakness, especially during August–November and when accompanied by neck or back pain and a recent history of febrile respiratory illness. Increasing awareness in frontline settings such as emergency departments should aid rapid recognition and hospitalization for AFM.

Enterovirus infection and acute flaccid myelitis

Recent outbreaks of limb paralysis similar to poliomyelitis, termed acute flaccid myelitis (AFM), have prompted intense investigation into potential etiology. Peaks of AFM were seen in the United States in 2012, 2014, 2016 and 2018, coincident with peaks in enterovirus transmission, particularly EV-D68. Similar peaks of AFM and EV-D68 circulation were reported in other parts of the world. The causal relationship between EV-D68 is still not widely accepted as it is for poliovirus and EV-A71, the latter of which is endemic in the US. Recent in vitro and mouse model data as well as enhanced-sensitivity diagnostic assays have provided further evidence linking the causal relationship between EV-D68 and AFM. In addition, an outbreak of EV-A71-associated AFM was recently described, highlighting the possibility of an additional emerging non-polio enterovirus of public health concern. As AFM is a devastating disease with poor prognosis in many children, particularly those with EV-D68, recent studies call for increased surveillance, pursuit of novel therapeutics and strategies to prevent transmission before the next outbreak.

A Bayesian approach for detecting a disease that is not being modeled

Over the past decade, outbreaks of new or reemergent viruses such as severe acute respiratory syndrome (SARS) virus, Middle East respiratory syndrome (MERS) virus, and Zika have claimed thousands of lives and cost governments and healthcare systems billions of dollars. Because the appearance of new or transformed diseases is likely to continue, the detection and characterization of emergent diseases is an important problem. We describe a Bayesian statistical model that can detect and characterize previously unknown and unmodeled diseases from patient-care reports and evaluate its performance on historical data.

Understanding Enterovirus D68-Induced Neurologic Disease: A Basic Science Review

In 2014, the United States (US) experienced an unprecedented epidemic of enterovirus D68 (EV-D68)-induced respiratory disease that was temporally associated with the emergence of acute flaccid myelitis (AFM), a paralytic disease occurring predominantly in children, that has a striking resemblance to poliomyelitis. Although a definitive causal link between EV-D68 infection and AFM has not been unequivocally established, rapidly accumulating clinical, immunological, and epidemiological evidence points to EV-D68 as the major causative agent of recent seasonal childhood AFM outbreaks in the US. This review summarizes evidence, gained from in vivo and in vitro models of EV-D68-induced disease, which demonstrates that contemporary EV-D68 strains isolated during and since the 2014 outbreak differ from historical EV-D68 in several factors influencing neurovirulence, including their genomic sequence, their receptor utilization, their ability to infect neurons, and their neuropathogenicity in mice. These findings provide biological plausibility that EV-D68 is a causal agent of AFM and provide important experimental models for studies of pathogenesis and treatment that are likely to be difficult or impossible in humans.