Seroepidemiology of Parechovirus A3 Neutralizing Antibodies, Australia, the Netherlands, and United States

Respiratory Arrest in a Late Preterm Infant Presenting for a 2-Week Well-Visit

A 13-day-old, late preterm male, born appropriate for gestational age, presented to the pediatric clinic for his routine 2-week well visit with less than 1-day history of decreased oral intake and lethargy. During the baby's well exam, he acutely decompensated and required resuscitation and transfer to the emergency department, where he was intubated for frequent apneic events. He was admitted to the NICU for management and further workup. Physical examination and initial laboratory tests were unremarkable. An EEG demonstrated electrographic and clinical seizures. His initial MRI was unremarkable, and infection studies revealed the diagnosis. We review the patient's initial presentation, evaluation, hospital course, and the long-term implications of his diagnosis.

Novel Human Parechovirus 3 Diversity, Recombination, and Clinical Impact Across 7 Years: An Australian Story

BACKGROUND

A novel human parechovirus 3 Australian recombinant (HPeV3-AR) strain emerged in 2013 and coincided with biennial outbreaks of sepsis-like illnesses in infants. We evaluated the molecular evolution of the HPeV3-AR strain and its association with severe HPeV infections.

METHODS

HPeV3-positive samples collected from hospitalized infants aged 5-252 days in 2 Australian states (2013-2020) and from a community-based birth cohort (2010-2014) were sequenced. Coding regions were used to conduct phylogenetic and evolutionary analyses. A recombinant-specific polymerase chain reaction was designed and utilized to screen all clinical and community HPeV3-positive samples.

RESULTS

Complete coding regions of 54 cases were obtained, which showed the HPeV3-AR strain progressively evolving, particularly in the 3' end of the nonstructural genes. The HPeV3-AR strain was not detected in the community birth cohort until the initial outbreak in late 2013. High-throughput screening showed that most (>75%) hospitalized HPeV3 cases involved the AR strain in the first 3 clinical outbreaks, with declining prevalence in the 2019-2020 season. The AR strain was not statistically associated with increased clinical severity among hospitalized infants.

CONCLUSIONS

HPeV3-AR was the dominant strain during the study period. Increased hospital admissions may have been from a temporary fitness advantage and/or increased virulence.

Recombinant parechovirus A3 possibly causes various clinical manifestations, including myalgia; findings in Yamagata, Japan in 2019

BACKGROUND

Parechovirus A3 was first reported in 2004 and has been recognized as a causative agent of mild and severe infections in children. Since we first reported an outbreak of adult parechovirus A3-associated myalgia in Yamagata, Japan in 2008, this disease has since been recognized across Japan, but has not yet been reported from other countries.

AIM

We analysed 19 cases of parechovirus A3 infections identified in Yamagata in 2019 to further clarify the epidemiology of this disease.

METHODS

We performed phylogenetic analyses of parechovirus A3 isolates and analysed the clinical manifestations and the genomic clusters.

RESULTS

There were two clusters, with cluster 2019B replacing 2019 A around October/November. Phylogenetic analysis revealed that 2019B cluster strains and Australian recombinant strains, which appeared between 2012 and 2013, were grouped in one cluster at non-structural protein regions, suggesting that the ancestor to these regions of 2019B cluster strains were Australian recombinant lineage strains. The strains from both clusters caused various infections in children including myalgia. These findings strongly support that parechovirus A3 strains cause myalgia and other paediatric infections irrespective of the virus strains involved, including recombinant strains.　　.

CONCLUSIONS

We have reported repeatedly sporadic cases of myalgia and here showed that recombinant strains also cause myalgia. We hope our experiences will help better understand these infections and possibly result in detection of more cases in the world.

Parechovirus A Infection of the Intestinal Epithelium: Differences Between Genotypes A1 and A3

Human parechovirus (PeV-A), one of the species within the Picornaviridae family, is known to cause disease in humans. The most commonly detected genotypes are PeV-A1, associated with mild gastrointestinal disease in young children, and PeV-A3, linked to severe disease with neurological symptoms in neonates. As PeV-A are detectable in stool and nasopharyngeal samples, entry is speculated to occur via the respiratory and gastro-intestinal routes. In this study, we characterized PeV-A1 and PeV-A3 replication and tropism in the intestinal epithelium using a primary 2D model based on human fetal enteroids. This model was permissive to infection with lab-adapted strains and clinical isolates of PeV-A1, but for PeV-A3, infection could only be established with clinical isolates. Replication was highest with infection established from the basolateral side with apical shedding for both genotypes. Compared to PeV-A1, replication kinetics of PeV-A3 were slower. Interestingly, there was a difference in cell tropism with PeV-A1 infecting both Paneth cells and enterocytes, while PeV-A3 infected mainly goblet cells. This difference in cell tropism may explain the difference in replication kinetics and associated disease in humans.

Parent-administered Neurodevelopmental Follow up in Children After Picornavirus CNS Infections

BACKGROUND

Data on the neurodevelopment of children who experienced central nervous system (CNS) infections with enteroviruses (EV) or parechoviruses (hPeV) is scarce and mostly limited to follow up of short-term outcomes.

METHODS

Parents of children who presented between 2014 and 2019, underwent a lumbar puncture and whose cerebrospinal fluid was polymerase chain reaction positive for EV or hPeV, were asked to complete a care-giver-administered neurodevelopmental assessment tool (The Ages and Stages Instrument [ASQ3]). Clinical data of the infective episode were collected from patient notes.

RESULTS

Of 101 children, 43 (10 hPeV+, 33 EV+) submitted ASQ3 results. Median age at assessment was 38.9 months (interquartile range, 15.4-54.8), the follow-up interval 3 years (median 37 months; interquartile range, 13.9-53.1). Age, inflammatory markers, and cerebrospinal fluid pleocytosis during the infective event were not associated with ASQ3 scores. In 23 children (17 EV+, 6 hPeV+), no neurodevelopmental concerns were reported. Two more had preexisting developmental delay and were excluded. Of the remaining, 18/41 (43.9%) reported ASQ3 scores indicating need for monitoring or professional review in at least 1 category, not differing by pathogen (EV 14/31, 45.2%; hPeV 4/10, 40%; P = 0.71). Seven children will require formal review, scoring ≥2 SD below the mean in at least 1 category (6/31 EV+, 1/10 hPeV+, P = 0.7), 3 scored ≥2 SD below the mean in more than 1 area.

CONCLUSIONS

Parent-administered developmental assessment of children with a history of early picornavirus infection of the CNS identified a subgroup that requires formal neurodevelopmental review. Wider application of community-based developmental screening will complement our understanding of the impact of CNS infections in early childhood.

Maternal parechovirus A (PeV-A) shedding, serostatus, and the risk of central nervous system PeV-A infections in infants

BACKGROUND

Parechovirus A (PeV-A) has emerged as a leading cause of infant central nervous system (CNS) infections. Risk factors associated with infant acquisition of PeV-A are not well understood.

METHODS

We conducted prospective PeV-A/enterovirus (EV) CNS infection surveillance, enrolling 461 hospitalized infants <90 days old who underwent sepsis evaluations and lumbar puncture during 2011-2012. Infants were grouped by RT-PCR detection of PeV-A, EV, or neither virus (Neg) in CSF. We collected demographic/clinical data and tested specimens from all infants. For 427 mothers, we collected demographic/clinical data and evaluated PeV-A3 and EV shedding, and PeV-A3 neutralizing antibody for 147 mothers.

RESULTS

PeV-A was detected in 40 infants (8.7%), 4 in 2011 and 36 in 2012. EV was detected in 35 infants (7.6%), 16 in 2011, and 19 in 2012. PeV-A infected infants presented with irritability, abdominal discomfort, fever, and tachycardia, plus both lymphopenia and absence of CSF pleocytosis which help differentiate PeV-A from EV CNS infection. PeV-A was detected in 9/427 maternal throat swabs; eight of their infants also had PeV-A CNS infection. Infants whose mothers had PeV-A3-positive throat swabs were more likely to be PeV-A3-positive than infants whose mothers had negative throat swabs (relative risk [RR], 13.4 [95% CI, 8.6 - 20.7]). Maternal PeV-A3 seropositivity decreased with increasing maternal age. Mothers of PeV-A-positive infants had lower median PeV-A3 neutralizing titers and were more likely seronegative.

CONCLUSIONS

Maternal viral shedding, serostatus and neutralization titers appear to be important factors in infant PeV-A3 CNS infections.

Neutralising Antibodies against Enterovirus and Parechovirus in IVIG Reflect General Circulation: A Tool for Sero-Surveillance

Non-polio enteroviruses (NPEV) and parechoviruses (PeV) are widespread pathogens that cause significant morbidity. Surveillance is based on culturing or genotyping of virus strains found in clinical samples. Sero-surveillance, by measuring neutralising antibodies (nAb) through virus neutralisation assays (VNA), could provide additional information as it offers a more comprehensive overview of exposure to circulating types in the general population. In our study we evaluated Intravenous immunoglobulins (IVIG) to generate sero-surveillance data. We performed VNA of nineteen NPEV and PeV with Dutch IVIG batches from two different time points (2010 and 2017) and an IVIG batch from Vietnam (2011). We compared our findings with geno- and sero-surveillance data and evaluated changes over time and between the two countries. Our findings show a good correlation with what is known from geno-surveillance data. The highest nAb titres were found against strains from Enterovirus B, while we did not observe nAb titres against strains belonging to Enterovirus C. In conclusion, we demonstrated that sero-surveillance by means of IVIG can be used to obtain insight into circulation of EV and PeV genotypes. This is of particular interest for public health, to evaluate changes over time and population susceptibility to emerging genotypes.

Parechovirus A Infections in Healthy Australian Children During the First 2 Years of Life: A Community-based Longitudinal Birth Cohort Study

Background

Hospital-based studies identify parechovirus (PeV), primarily PeV-A3, as an important cause of severe infections in young children. However, few community-based studies have been published and the true PeV infection burden is unknown. We investigated PeV epidemiology in healthy children participating in a community-based, longitudinal birth cohort study.

Methods

Australian children (n = 158) enrolled in the Observational Research in Childhood Infectious Diseases (ORChID) study were followed from birth until their second birthday. Weekly stool and nasal swabs and daily symptom diaries were collected. Swabs were tested for PeV by reverse-transcription polymerase chain reaction and genotypes determined by subgenomic sequencing. Incidence rate, infection characteristics, clinical associations, and virus codetections were investigated.

Results

PeV was detected in 1423 of 11 124 (12.8%) and 17 of 8100 (0.2%) stool and nasal swabs, respectively. Major genotypes among the 306 infection episodes identified were PeV-A1 (47.9%), PeV-A6 (20.1%), and PeV-A3 (18.3%). The incidence rate was 144 episodes (95% confidence interval, 128–160) per 100 child-years. First infections appeared at a median age of 8 (interquartile range, 6.0–11.7) months. Annual seasonal peaks changing from PeV-A1 to PeV-A3 were observed. Infection was positively associated with age ≥6 months, summer season, nonexclusive breastfeeding at age <3 months, and formal childcare attendance before age 12 months. Sole PeV infections were either asymptomatic (38.4%) or mild (32.7%), while codetection with other viruses in stool swabs was common (64.4%).

Conclusions

In contrast with hospital-based studies, this study showed that diverse and dynamically changing PeV genotypes circulate in the community causing mild or subclinical infections in children.

Parechovirus can cause severe illnesses in children. However, studies focus mainly on hospitalized populations. True disease burden in the community remains largely unknown. From our community-based cohort, we found diverse parechovirus genotypes in the community, causing mild or subclinical infections in children.

Proposal for the Recognition of a New Disease Concept from Japan: Parechovirus A3-Associated Myalgia

Parechovirus A3 (PeVA3) was first reported in 2004 and has been recognized as a causative agent of mild and severe infectious diseases in children. We first reported an outbreak of PeVA3-associated myalgia (PeVA3-M) in Yamagata, Japan, in 2008. We have repeatedly observed PeVA3-M cases in 2011, 2014, and 2016, and identified the first child case in 2014. Reports of PeVA3-M have increased since 2014, indicating that the recognition of PeVA3-M has spread across Japan. The findings showed that PeVA3-M commonly occurs among adults aged 30-40 years, particularly in males. Elevation of creatinine phosphokinase, C-reactive protein, and myoglobin, as well as magnetic resonance imaging findings, suggest inflammation of the muscles and/or fascia of the four limbs. Patients recover within 1-2 weeks without any sequelae. A longitudinal molecular epidemiological study in Yamagata revealed that PeVA3 strains cause a variety of diseases, ranging from mild to severe, including PeVA3-M, in subjects ranging from neonates to adults, irrespective of their genetic cluster. As PeVA3-M has not yet been reported abroad, more widespread recognition of PeVA3-M as an emerging disease is important. We hope this review will help clinicians and researchers in understanding PeVA3-M and therefore advance related research in Japan as well as around the world.

Clinical Characteristics of Epidemic Myalgia Associated with Human Parechovirus Type 3 during the Summer of 2019

Objective Epidemic myalgia associated with human parechovirus type 3 (EM-HPeV3) is characterized by severe muscle pain and weakness on the limbs and trunk with a fever. No outbreak of EM-HPeV3 has been reported since 2016, and its clinical characteristics have not been sufficiently clarified. We herein report a series of EM-HPeV3 cases during the summer of 2019 and clarify the clinical characteristics of EM-HPeV3. Methods The diagnosis of EM-HPeV3 was established when the patients met both of the following criteria: (1) Patients developed severe muscle pain and weakness with a fever within a week, and those symptoms resolved within a month; and (2) HPeV3 was detected in either a throat swab or fecal specimen of the patient by polymerase chain reaction. We reviewed the medical records of these patients retrospectively. Results Seven patients met the criteria (6 men and 1 woman, age 34 to 47 years old). Myalgia was observed on the thigh, lower legs, upper arms, and forearms in seven, five, two, and five patients, respectively. Four patients showed distal dominant weakness on the arms, while none of the patients showed proximal dominant weakness on the arms. Of the six patients examined, five showed reduced tendon reflexes on all four limbs. One patient showed slight myogenic change and increased insertion activities on needle electromyography. Conclusion We observed seven cases of EM-HPeV3 during the summer of 2019. Reduced tendon reflexes and distal dominancy of muscle pain and weakness on the arms are considered its distinct clinical features.

Epidemic and Inter-epidemic Burden of Pediatric Human Parechovirus Infection in New South Wales, Australia, 2017-2018

BACKGROUND

Human parechovirus (HPeV) typically infects young children, and although infection is often asymptomatic, some types (eg, HPeV3) are associated with severe clinical manifestations, including central nervous system infection or sepsis-like syndrome, particularly affecting young infants. The third documented national epidemic of HPeV occurred in Australia in 2017-2018.

METHODS

Four public laboratories that perform almost all of the HPeV PCR testing in New South Wales provided data regarding HPeV tests performed from July 1, 2017 to June 30, 2018. Limited demographic and clinical data were obtained from electronic medical records for laboratory test-positive cases that presented to each of the 3 pediatric hospitals in New South Wales.

RESULTS

Five hundred eighty-one HPeV-positive samples obtained from 395 cases were included in the analysis. The peak of the outbreak occurred in late November 2017 (approximately 35 new cases each week), with the main HPeV epidemic occurring between the spring and summer months of September 2017 to January 2018; although this seasonality was observed primarily in infants less than 12 months of age. Among the 388 pediatric cases, almost half were younger than 2 months (188; 47%) and only 10 were children older than 2 years. The annualized estimated incidence of laboratory confirmed HPeV infection in children was approximately 142.4 cases per 100,000 children younger than 5 years in New South Wales during the epidemic season.

CONCLUSIONS

The large burden of HPeV infection and disease identified in young infants in this and previous Australian studies highlight the need for more comprehensive national surveillance of HPeV infections and improved prevention strategies.

Parechovirus A prevalence in adults in The Netherlands

Human parechoviruses (HPeV) of the species Parechovirus A are highly prevalent disease-causing pathogens in children worldwide. HPeVs are capable of causing severe disease in adults as well, but the prevalence in adults may be much lower. The aim of our present study was to determine the prevalence of HPeV in clinical samples from adults sent in for diagnostic procedures in a tertiary hospital in the Netherlands. From a total of 10,645 samples obtained from 6175 patients, 20 samples from 11 patients (0.18%) tested positive for HPeV by RT-PCR. Two patients were positive for HPeV-1, two for HPeV-3, and one for HPeV-6. Six HPeVs could not be typed. Eight of the 11 HPeV-positive patients were immunocompromised. Due to comorbidity, we were unable to attribute the patients’ clinical symptoms to the HPeV infection. The HPeV prevalence in adults found in this study is low compared to HPeV prevalence in children. This may be largely explained by the high seropositivity rates in adults, although there could be other mechanisms involved.

Parechovirus A Pathogenesis and the Enigma of Genotype A-3

Parechovirus A is a species in the Parechovirus genus within the Picornaviridae family that can cause severe disease in children. Relatively little is known on Parechovirus A epidemiology and pathogenesis. This review aims to explore the Parechovirus A literature and highlight the differences between Parechovirus A genotypes from a pathogenesis standpoint. In particular, the curious case of Parechovirus-A3 and the genotype-specific disease association will be discussed. Finally, a brief outlook on Parechovirus A research is provided.

Evolutionary analysis of human parechovirus type 3 and clinical outcomes of infection during the 2017-18 Australian epidemic

Human parechovirus type 3 (HPeV3) can cause severe sepsis-like illness in young infants and may be associated with long term neurodevelopmental delay later in childhood. We investigated the molecular epidemiology of HPeV infection in thirty three infants requiring hospitalization before, during and after the peak of the 2017/18 HPeV epidemic wave in Australia. During the peak of the epidemic, all cases were infected with an HPeV3, while before and after the peak, HPeV1 was the predominant type detected. The predominant HPeV3 was the recombinant HPeV3 also detected in the 2013/14 and 2015/16 Australian epidemics. Sepsis-like or meningitis-like symptoms were only reported in cases infected with the recombinant HPeV3. Phylogenetic analysis of the recombinant HPeV3 revealed that the virus continued to evolve, also between the Australian outbreaks, thus indicating continued circulation, despite not being detected and reported in Australia or elsewhere in between epidemic waves. The recombinant HPeV3 continued to show a remarkable stability in its capsid amino acid sequence, further strengthening our previous argument for development of a vaccine or immunotherapeutics to reduce the severity of HPeV3 outbreaks due to this virus.

High frequency and diversity of parechovirus A in a cohort of Malawian children

Parechoviruses (PeVs) are highly prevalent viruses worldwide. Over the last decades, several studies have been published on PeV epidemiology in Europe, Asia and North America, while information on other continents is lacking. The aim of this study was to describe PeV circulation in a cohort of children in Malawi, Africa. A total of 749 stool samples obtained from Malawian children aged 6 to 60 months were tested for the presence of PeV by real-time PCR. We performed typing by phylogenetic and Basic Local Alignment Search Tool (BLAST) analysis. PeV was found in 57% of stool samples. Age was significantly associated with PeV positivity (p = 0.01). Typing by phylogenetic analysis resulted in 15 different types, while BLAST typing resulted in 14 different types and several indeterminate strains. In total, six strains showed inconsistencies in typing between the two methods. One strain, P02-4058, remained untypable by all methods, but appeared to belong to the recently reclassified PeV-A19 genotype. PeV-A1, -A2 and -A3 were the most prevalent types (26.8%, 13.8% and 9.8%, respectively). Both the prevalence and genetic diversity found in our study were remarkably high. Our data provide an important contribution to the scarce data available on PeV epidemiology in Africa.