Circulation of Enterovirus D68 during Period of Increased Influenza-Like Illness, Maryland, USA, 2021

Beyond polio: Exploring non-polio enteroviruses, global health preparedness, and the "Disease X" paradigm

Background and Aims

Disease X represents the possibility that an unidentified infection may spread globally and start a pandemic. This study explored various aspects of emerging non-polio enteroviruses (NPEVs) as a possible source of "Disease X," an enigmatic agent declared by the World Health Organization, and discussed the potential impact of NPEVs on global public health.

Methods

In this perspective article, we collected information from publicly available sources such as Google Scholar, PubMed, and Scopus. We used NPEVs, viral diseases, pandemics, and zoonotic diseases as keywords. We extracted information from the most relevant articles.

Results

Notable outbreaks caused by NPEVs include enterovirus D68 (EV-D68) and enterovirus A71 (EV-A71), among many others. With a focus on therapeutic and preventative components, alternate modes of therapy, and the development of broad-spectrum antivirals, this analysis looks at the origin, epidemiology, genetic alterations, transmission dynamics, and disease pathophysiology of NPEVs. The information presented in the review indicates the current risk assessment of NPEVs, taking into account the following factors: the need for research and therapeutic interventions, the diversity of clinical manifestations, the impact of genetic variability on virulence, the persistence of emergence despite vaccination efforts, recurrent outbreaks, and the global impact of these viruses.

Conclusion

There is a possibility that NPEVs could trigger global pandemics based on their zoonotic origins and urges for complete readiness, continuous research, cooperation, and a comprehensive strategy to combat emerging infectious diseases in a constantly changing global environment. It is peak time to acknowledge how important it is to abide by safety and health laws to prevent these illnesses.

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.

Wastewater-based epidemiology revealed in advance the increase of enterovirus circulation during the Covid-19 pandemic

Wastewater-based epidemiology (WBE) was conducted to track Enteroviruses (EVs) circulation in the Milan metropolitan area (Northern Italy) during Covid-19 pandemic (March 2020-December 2022). 202 composite 24-hour wastewater samples (WWSs) were collected weekly from March 24, 2020, to December 29, 2022 at the inlet of two wastewater treatment plants (WWTP) in Milan (1.5 million inhabitants). EV-RNA was quantified and molecular characterization of non-polio EVs (NPEV) was performed by Sanger sequence analysis. Data from WWS were matched with virological data collected in the framework of Influenza-Like Illness (ILI) surveillance in the same place and time. EV-RNA was identified in 88.2 % of WWSs. The peak in EVs circulation was observed in late August 2020 (upon conclusion of the first national lockdown), in late August 2021, and in mid-April 2022. EV-RNA concentration in WWS (normalized as copies/d/1000 people) at peak of circulation presented a yearly increase (2020: 2.47 × 1010; 2021: 6.81 × 1010; 2022: 2.14 × 1011). This trend overlapped with trend in EV-positivity rate in ILI cases, expanded from 21.7 % in 2021 to 55.6 % in 2022. EV trends in WWS preceded clinical sample detections in 2021 and 2022 by eight and five weeks, respectively, acting as an early warning of outbreak. Although sequencing of EV-positive WWSs revealed the presence of multiple EV strains, typing remained inconclusive. Molecular characterization of EVs in clinical samples revealed the co-circulation of several genotypes: EV-A accounted for 60 % of EVs, EV-B for 16.7 %, EV-D68 for 23.3 %. EVs were circulating in Milan metropolitan area between March 2020 and December 2022. The epidemiological trends unfolded the progressive accumulation of EV transmission in the population after removal of Covid-19 restrictions. The increased circulation of EVs in 2021-2022 was identified at least 35 days in advance compared to the analysis of clinical data. The inconclusive results of Sanger sequencing lookout for improvement and innovative molecular approaches to deepen track EVs.

Evolution of Influenza A(H3N2) Viruses in 2 Consecutive Seasons of Genomic Surveillance, 2021-2023

Background

The circulation and the genomic evolution of influenza A(H3N2) viruses during the 2021/2022 and 2022/2023 seasons were studied and associated with infection outcomes.

Methods

Remnant influenza A-positive samples following standard-of-care testing from patients across the Johns Hopkins Health System (JHHS) were used for the study. Samples were randomly selected for whole viral genome sequencing. The sequence-based pEpitope model was used to estimate the predicted vaccine efficacy (pVE) for circulating H3N2 viruses. Clinical data were collected and associated with viral genomic data.

Results

A total of 121 683 respiratory specimens were tested for influenza at JHHS between 1 September 2021 and 31 December 2022. Among them, 6071 (4.99%) tested positive for influenza A. Of these, 805 samples were randomly selected for sequencing, with hemagglutinin (HA) segments characterized for 610 samples. Among the characterized samples, 581 were H3N2 (95.2%). Phylogenetic analysis of HA segments revealed the exclusive circulation of H3N2 viruses with HA segments of the 3C.2a1b.2a.2 clade. Analysis of a total of 445 complete H3N2 genomes revealed reassortments; 200 of 227 of the 2022/2023 season genomes (88.1%) were found to have reassorted with clade 3C.2a1b.1a. The pVE was estimated to be -42.53% for the 2021/2022 season and 30.27% for the 2022/2023 season. No differences in clinical presentations or admissions were observed between the 2 seasons.

Conclusions

The increased numbers of cases and genomic diversity of influenza A(H3N2) during the 2022/2023 season were not associated with a change in disease severity compared to the previous influenza season.

Clinical and molecular characteristics of the 2022 Enterovirus-D68 outbreak among hospitalized children, Ohio, USA

BACKGROUND

Enterovirus-D68 (EV-D68) has appeared biennially in the United States following the 2014 outbreak. It has gained epidemiologic and clinical relevance and was identified as an important pathogen associated with severe respiratory and central nervous system diseases. We aim to describe the clinical and molecular characteristics of the post-pandemic 2022 Enterovirus-D68 outbreak in children evaluated in a tertiary pediatric hospital in Columbus, Ohio.

METHODS

EV-D68 RT-PCR was performed on nasopharyngeal specimens collected during Jun-Nov 2022 from children (<18 years), identified by 1) physician-order or 2) random selection of 10-15 specimens weekly that were Rhinovirus/Enterovirus-positive by physician-ordered respiratory virus panel. Patients who tested positive for EV-D68 were identified and clinical data and outcomes were analyzed. Partial viral VP1 region was sequenced and characterized.

RESULTS

Forty-four children positive for EV-D68 were identified, among which 88.6 % of patients presented with respiratory symptoms and 61.4 % required PICU admission. Two patients presented with AFM that was attributed to EV-D68. EV-D68 sequences from 2022 clustered within the B3 subclade.

CONCLUSIONS

A significant proportion of children identified with EV-D68 during the 2022 outbreak had respiratory compromise requiring PICU admission. As the virus continues evolving, it is important to monitor the activity of EV-D68, characterizing these strains clinically and genetically, which will help to understand the viral pathogenicity and virulence.

Insights into the molecular evolution of enterovirus D68

Enterovirus D68 (EV-D68) is a respiratory virus that primarily affects children and has been associated with sporadic outbreaks of respiratory illness worldwide. In the present study, temporal spreading and molecular evolution of EV-D68 clades (A1, A2, B, B1, B2, B3, and C) were evaluated. Bayesian coalescent analysis was performed to study viral evolution. Data from 976 whole-genome sequences (WGSs) collected between 1977 and 2022 were evaluated. For A1, the most recent common ancestor was dated to 2005-04-17 in the USA; for A2 it was 2003-12-23 in China; for B, it was 2003-07-06 in China; for B1, it was 2010-03-21 in Vietnam; for B2, it was 2006-11-25 in Vietnam; for B3, it was 2011-01-15 in China; and for C, it was 2000-06-27 in the USA. The molecular origin of EV-D68 was in Canada in 1995, and later it was disseminated in France in 1997, the USA in 1999, Asia in 2008, the Netherlands in 2009, New Zealand in 2010, Mexico in 2014, Kenya in 2015, Sweden in 2016, Switzerland in 2018, Spain in 2018, Belgium in 2018, Australia in 2018, and Denmark in 2019. In 2022, this virus circulated in the USA. In conclusion, EV-D68 originated in Canada in the 1990s and spread to Europe, Asia, Oceania, Latin America, and Africa.

Enterovirus D68 Outbreak in Children, Finland, August-September 2022

We observed an intense enterovirus D68 outbreak in children in southwest Finland in August-September 2022. We confirmed enterovirus D68 infection in 56 children hospitalized for respiratory illnesses and in 1 child with encephalitis but were not able to test all suspected patients. Continuing surveillance for enterovirus D68 is needed.

EV-D68 virus-like particle vaccines elicit cross-clade neutralizing antibodies that inhibit infection and block dissemination

Enterovirus D68 (EV-D68) causes severe respiratory illness in children and can result in a debilitating paralytic disease known as acute flaccid myelitis. No treatment or vaccine for EV-D68 infection is available. Here, we demonstrate that virus-like particle (VLP) vaccines elicit a protective neutralizing antibody against homologous and heterologous EV-D68 subclades. VLP based on a B1 subclade 2014 outbreak strain elicited comparable B1 EV-D68 neutralizing activity as an inactivated viral particle vaccine in mice. Both immunogens elicited weaker cross-neutralization against heterologous viruses. A B3 VLP vaccine elicited more robust neutralization of B3 subclade viruses with improved cross-neutralization. A balanced CD4⁺ T helper response was achieved using a carbomer-based adjuvant, Adjuplex. Nonhuman primates immunized with this B3 VLP Adjuplex formulation generated robust neutralizing antibodies against homologous and heterologous subclade viruses. Our results suggest that both vaccine strain and adjuvant selection are critical elements for improving the breadth of protective immunity against EV-D68.

An increase in enterovirus D68 circulation and viral evolution during a period of increased influenza like illness, The Johns Hopkins Health System, USA, 2022

BACKGROUND

An increase in influenza like illness in children and adolescents at the Johns Hopkins Health system during summer 2022 was associated with increased positivity for enterovirus/ rhinovirus. We sought to characterize the epidemiology and viral evolution of enterovirus D68 (EV-D68).

METHODS

A cohort of remnant respiratory samples tested at the Johns Hopkins Microbiology Laboratory was screened for EV-D68. EV-D68 positives were characterized by whole genome sequencing and viral loads were assessed by droplet digital PCR (ddPCR). Genomic changes and viral loads were analyzed along with patients' clinical presentations.

RESULTS

Of 566 screened samples, 126 were EV-D68 (22.3%). The median age of EV-D68 infected patients was four years, a total of 52 required supplemental oxygen (41.3%), and 35 (27.8%) were admitted. Lung disease was the most frequent comorbidity that was associated with hospitalization. A total of 75 complete and 32 partial genomes were characterized that made a new cluster within the B3 subclade that was closest to US genomes from 2018. Amino acid changes within the BC and DE loops were identified from 31 genomes (29%) which correlated with an increase in average viral load in respiratory specimens and the need for supplemental oxygen.

CONCLUSIONS

EV-D68 outbreaks continue to cause influenza like illness that could be overwhelming for the health system due to a significant demand for high flow oxygen. Viral evolution and an increase in the susceptible population are likely driving the trends of the increased EV-D68 infections.

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.

Off-season circulation and characterization of enterovirus D68 with respiratory and neurological presentation using whole-genome sequencing

To explore an off-season enterovirus D68 (EV-D68) upsurge in the winter season of 2019/2020, we adapted a whole-genome sequencing approach for Nanopore Sequencing for 20 hospitalized patients with accompanying respiratory or neurological presentation. Applying phylodynamic and evolutionary analysis on Nextstrain and Datamonkey respectively, we report a highly diverse virus with an evolutionary rate of 3.05 × 10^-3 substitutions per year (entire EV-D68 genome) and a positive episodic/diversifying selection with persistent yet undetected circulation likely driving evolution. While the predominant B3 subclade was identified in 19 patients, one A2 subclade was identified in an infant presenting with meningitis. Exploring single nucleotide variations using CLC Genomics Server showed high levels of non-synonymous mutations, particularly in the surface proteins, possibly highlighting growing problems with routine Sanger sequencing for typing enteroviruses. Surveillance and molecular approaches to enhance current knowledge of infectious pathogens capable of pandemic potential are paramount to early warning in health care facilities.