Human parechovirus infections and child myositis cases associated with genotype 3 in Osaka City, Japan, 2014

Prevalence and genetic diversity of Parechovirus A in children with diarrhea in Beijing, China, 2017-2019

We analyzed the prevalence and genotypes of Parechovirus A (PeV-A) in children with diarrhea in Beijing, China, 2017-2019. A total of 1734 stool samples collected from children <5 years of age with diarrhea were tested for the presence of PeV-A. Viral RNA was detected by real-time RT-PCR, and then genotyped by nested RT-PCR. We detected PeV-A in 93 (5.4%, 93/1734) samples, of which 87 could be genotyped by amplification of either the complete or partial VP1 region or the VP3/VP1 junction region. The median age of PeV-A infected children was 10 months. Most PeV-A infections were observed between August and November, with a peak in September. Seven known genotypes of PeV-A1A, -A1B, -A3, -A4, -A6, -A8 and -A11 were detected and PeV-A1B was the most prevalent genotype. Coinfection with other diarrheal viruses was observed in 30.1% (28/93) of PeV-A positive samples. All strains of PeV-A1A, -A1B, -A4 and -A6 obtained in this study contained the arginine-glycine-aspartic (RGD) motif, while all strains of PeV-A3, -A8 and -A11 lacked it. This study revealed a high genetic diversity of PeV-A circulating in Beijing and PeV-A11 was reported for the first time in children with diarrhea in China.

Severe Generalized Epidemic Myalgia in an Adult due to Human Parechovirus Type 3: A Case Report

Parechovirus A type 3 (PeVA3) is most commonly transmitted to adults from children. Although PeVA3 infection is rarely diagnosed, as the symptoms are generally mild and self-limiting, this infection has been associated with epidemic myalgia in Japan. The patient, a 37-year-old man, presented with severe generalized myalgia, inability to open his mouth, and orchitis, which resolved over a period of 10 days. All members of his family were thought to have been infected with PeVA3 during a visit to an amusement park. Although the source of infection and inability to open his mouth are atypical, the acute generalized muscle symptoms made us suspect epidemic myalgia and enabled us to make a diagnosis of PeVA3 infection.

Necrotizing enterovirus myositis in a pediatric renal transplant recipient

BACKGROUND

Enteroviruses can cause severe infections, including viral myocarditis, meningitis, acute flaccid myelitis, and viral myositis.

METHODS/RESULTS

We report a 3-year-old female renal transplant recipient who presented to a tertiary care hospital with elevated serum liver aminotransferases and subsequently developed proximal muscle pain, weakness, and respiratory distress during the first week of hospitalization. Imaging of the lower extremities revealed diffuse myositis of the proximal thigh and pelvic muscles. A muscle biopsy was obtained and revealed necrotizing myositis with immunostaining positive for enterovirus, consistent with a diagnosis of enterovirus necrotizing myositis. She had complete resolution of symptoms with steroids, intravenous immune globulin, reduced tacrolimus dose, and physical therapy.

CONCLUSIONS

Enterovirus myositis should be included in the differential diagnosis for necrotizing myositis following renal transplantation in children.

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.

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.

Human parechovirus are emerging pathogens with broad spectrum of clinical syndromes in adults

Parechoviruses are emerging pathogens of humans often affecting the pediatric age group, with a growing line of evidence implicating them as agents of a broad spectrum of clinical syndromes in adults. However, because many clinicians are not familiar with the manifestation of the infections, they are not included in the list of diagnostic pathogens. Furthermore, due to the indistinguishable feature of the infection compared with other common pathogens, a large number of cases are likely to go unchecked. Some may develop asymptomatic infection and recover without overt clinical disease. In this manuscript, we reviewed available literature on parechovirus infection in adult and summarized information relating to epidemiology, clinical manifestation, laboratory diagnosis, and therapeutics. The information provided should help in early case detection and support an evidence-based clinical decision.

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 Myalgia Associated with Human Parechovirus Type 3 Infection

A 42-year-old man was hospitalized due to a fever, orchiodynia, and extremely severe myalgia predominantly in the extremities, which made it difficult for him to stand or walk. He had a history of contact with his son who had acute upper respiratory infection. Based on the characteristic clinical symptoms and detection of the partial sequence of human parechovirus type 3 (HPeV3) in throat swabs as well as stool and serum samples, he was diagnosed with epidemic myalgia associated with HPeV3 infection. Because HPeV3 infection is widespread among children in Japan, HPeV3-associated myalgia should be considered when adult patients manifest such distinguishing clinical characteristics.

Novel human reovirus isolated from children and its long-term circulation with reassortments

Mammalian orthoreovirus (MRV), also known as reovirus, was discovered in the 1950s and became the first reported segmented double-stranded RNA virus. MRVs have since been found in a variety of animal species, including humans. However, reports on MRV infections are scarce due to the rarity of their symptomatic occurrence. In Japanese surveillance studies, MRVs have been detected as gastrointestinal pathogens since 1981, with a total of 135 records. In Osaka City, Japan, MRV was first isolated in 1994 from a child with meningitis, and then in 2005 and 2014 from children with gastroenteritis. Here, we conducted the first molecular characterization of human MRV isolates from Japan and identified a novel human reovirus strain belonging to MRV type 2, designated the MRV-2 Osaka strain. This strain, with all three isolates classified, is closely related to MRV-2 isolates from sewage in Taiwan and is relatively close to an MRV-2 isolate from a bat in China. Our data suggest that the MRV-2 Osaka strain, which has circulated amongst humans in Japan for at least two decades, has spread internationally.

Hepatitis B virus-related liver cirrhosis complicated with dermatomyositis: A case report

BACKGROUND

Twenty percent of patients infected with hepatitis B virus (HBV) develop extrahepatic manifestations with HBV detected in the lymph nodes, spleen, bone marrow, kidneys, and skin. HBV infection has been associated with some autoimmune disorders. Dermatomyositis (DM) is an idiopathic inflammatory myopathy, which involves a viral infection, and DM has been identified in patients infected with HBV, but there is no direct histological evidence for an association between HBV and DM.

CASE SUMMARY

We describe a familial HBV-infected patient admitted with liver function abnormality, rashes, a movement disorder, and an elevated level of creatine kinase (CK). A computed tomography scan of the lung showed pulmonary fibrosis, and a liver biopsy identified nodular cirrhosis. An electromyogram revealed myogenic damage, and a muscle biopsy showed nuclear migration in local sarcolemma and infiltration of chronic inflammatory cells. Immunohistochemical staining showed negative results for HBsAg and HBcAg. Fluorescence in situ hybridization showed a negative result for HBV DNA. The patient was diagnosed with HBV-related liver cirrhosis complicated with DM and was treated with methylprednisolone, mycophenolate mofetil, and lamivudine. Eight months later, the patient was readmitted for anorexia and fatigue. The blood examination showed elevated levels of aminotransferases and HBV DNA, however, the CK level was within the normal range. The patient developed a virological breakthrough and lamivudine was replaced with tenofovir.

CONCLUSION

DM in chronic HBV-infected patients does not always associate with HBV. Antiviral and immunosuppressive drugs should be taken into consideration.

Genetic diversity of human parechoviruses in stool samples, Germany

Human parechoviruses (HPeV) are ubiquitous and mainly occur in early infancy. They are known to cause various clinical manifestations including acute gastroenteritis. To gain insight into the diversity of circulating HPeV genotypes, stool samples from patients (n = 539) with clinical signs of infectious gastroenteritis which showed negative results for other common viral and bacterial enteric pathogens were obtained during three years, 2008 to 2010. Real-time RT-PCR showed HPeV RNA in 34 (6.3%) of the samples. The HPeV detection rate was highest (8.8%) in samples derived from infants and young children under the age of two years. Genotyping was based on VP3/VP1 junction nucleic acid sequences and revealed predominant HPeV-1B (n = 16) and HPeV-3 (n = 12) strains. Those prevailed minor HPeV-6 (n = 3) as well as HPeV-2, -4 and -5 (n = 1, each) strains. To ascertain the assigned HPeV-2 genotype of uncommon strain LPZ04-2008, analysis of complete coding sequences was performed. In complete VP1 analysis strain LPZ04-2008 showed 81.2% nucleic acid identity with HPeV-2 reference strain Williamson. In phylogenetic analysis VP1 of strain LPZ04-2008 clustered with a recent HPeV-2 strain from the UK. Regarding clinical manifestations, severe disease occurred HPeV-1B, -3 and - 6 infections. In conclusion, this paper a high genetic diversity of HPeV in stool samples, including rare strains. The investigation adds data on the whole coding sequences of the rare HPeV-2 strain. Genotyping results confirm previously reported association of more severe illness with HPeV-3 and HPeV-1B strains.

Parechovirus A3 (PeV-A3)-associated myalgia/myositis occurs irrespective of its genetic cluster: a longitudinal molecular epidemiology of PeV-A3 in Yamagata, Japan between 2003 and 2016

No longitudinal molecular epidemiology of parechovirus A3 (PeV-A3) over a decade is available and PeV-A3-associated myalgia/myositis has been reported only in Japan. Thus, we aimed to clarify the longitudinal molecular epidemiology of PeV-A3 with a major focus on the strains detected from PeV-A3-associated myalgia/myositis cases. We performed sequence and phylogenetic analysis for the VP1 region of PeV-A3 strains in Yamagata, Japan, between 2003 and 2016. The phylogenetic analysis indicated that PeV-A3 strains caused PeV-A3-associated myalgia/myositis as well as a variety of infectious diseases, ranging from mild to severe, in subjects ranging from neonates to adults, irrespective of genetic cluster or variations. PeV-A3 strains are causative agents of a variety of human diseases, irrespective of their genetic cluster. Furthermore, we consider that PeV-A3-associated myalgia/myositis may occur, not only in Japan, but also in other countries, as closely related PeV-A3 strains have been circulating around the world.

Severe epidemic myalgia with an elevated level of serum interleukin-6 caused by human parechovirus type 3: a case report and brief review of the literature

BACKGROUND

Human parechovirus type 3 (HPeV-3) is known to cause cold-like symptoms, diarrhea, or severe infections such as sepsis in infants and children. In adults, HPeV-3 infection is rarely diagnosed because the symptoms are generally mild and self-limiting; however, this infection has been linked to epidemic myalgia, regardless of the presence of underlying diseases, immunosuppression, or sex.

CASE PRESENTATION

We describe an adult case of severe systemic myalgia and orchiodynia after infection with HPeV-3, which was transmitted from the child of the patient. Interleukin-6 (IL-6) level was found to be elevated in the patient's serum.

CONCLUSION

Severe myalgia associated with HPeV-3 infection is potentially caused by an elevated serum level of IL-6.

Analysis of Human Parechovirus Genotypes in Yokohama District from 2000 to 2016

Human parechovirus (HPeV) infections in Yokohama City, Japan, were surveyed from 2000 to 2016. The sequence of the VP1 region of HPeVs was used to construct a phylogenetic tree and to reveal the putative amino acid (aa) sequences. Phylogenetic analysis showed the presence of 3 genotypes in Yokohama City: HPeV1 (25 specimens), HPeV3 (86 specimens), and HPeV4 (2 specimens). HPeV1 was detected nearly every year, with the highest number detected in 2014. HPeV3 was not detected until 2005, but was detected over a 1- or 3-yr period thereafter. HPeV1 was most prevalent from July to November, whereas HPeV3 peaked in July and August each year. HPeV1 was mainly detected in patients with infectious gastroenteritis or respiratory tract infections. In contrast, 87% of HPeV3-positive cases were in patients less than 2 months of age with a viral-induced fever. An analysis of the aa sequence of VP1 revealed a divergence within the same HPeV genotype, which was useful in analyzing the emergence and re-emergence of HPeV infections during the survey period. These findings suggest that molecular analysis of HPeVs may contribute to a better understanding of its epidemiology.

Antifungal azoles itraconazole and posaconazole exhibit potent in vitro antiviral activity against clinical isolates of parechovirus A3 (Picornaviridae)

Parechovirus A3 (Par-A3, formerly human parechovirus 3) is an emerging viral infection of the central nervous system in children. We used an automated, homogeneous, cell based assay to identify itraconazole and posaconazole as inhibitors of Par-A3, with antiviral activity below concentrations clinically attainable in pediatric patients. Currently, there is no approved antiviral treatment for Par-A3 infection, despite numerous reports of serious Par-A3 disease in neonates and infants.

Clinical features and seasonality of parechovirus infection in an Asian subtropical city, Hong Kong

BACKGROUND

The epidemiology of human parechovirus (HPeV) in Asia remains obscure. We elucidated the prevalence, seasonality, type distribution and clinical presentation of HPeV among children in Hong Kong.

METHODS

A 24-month prospective study to detect HPeV in children ≤36 months hospitalized for acute viral illnesses.

RESULTS

2.3% of the 3911 children examined had HPeV infection, with most (87.5%) concentrated in September-January (autumn-winter). 81.3% were HPeV1 and 12.5% were HPeV4, while HPeV3 was rare (2.5%). HPeV was a probable cause of the disease in 47.7% (42/88), mostly self-limiting including acute gastroenteritis, upper respiratory tract infection and maculopapular rash. A neonate developed severe sepsis-like illness with HPeV3 as the only pathogen detected. A high proportion (60.0%) of children coinfected with HPeV and other respiratory virus(es) had acute bronchiolitis or pneumonia. Six children with HPeV coinfections developed convulsion / pallid attack. Most rash illnesses exhibited a generalized maculopapular pattern involving the trunk and limbs, and were more likely associated with HPeV4 compared to other syndrome groups (36.4% vs. 3.1%, p = 0.011).

CONCLUSIONS

In Hong Kong, HPeV exhibits a clear seasonality (autumn-winter) and was found in a small proportion (2.3%) of young children (≤36 months) admitted with features of acute viral illnesses. The clinical presentation ranged from mild gastroenteritis, upper respiratory tract infection and febrile rash to convulsion and severe sepsis-like illness. HPeV3, which is reported to associate with more severe disease in neonates, is rare in Hong Kong. HPeV coinfection might associate with convulsion and aggravate other respiratory tract infections.

Human picornaviruses associated with neurological diseases and their neutralization by antibodies

Picornaviruses are the most commonly encountered infectious agents in mankind. They typically cause mild infections of the gastrointestinal or respiratory tract, but sometimes also invade the central nervous system. There, they can cause severe diseases with long-term sequelae and even be lethal. The most infamous picornavirus is poliovirus, for which significant epidemics of poliomyelitis were reported from the end of the nineteenth century. A successful vaccination campaign has brought poliovirus close to eradication, but neurological diseases caused by other picornaviruses have increasingly been reported since the late 1990s. In this review we focus on enterovirus 71, coxsackievirus A16, enterovirus 68 and human parechovirus 3, which have recently drawn attention because of their links to severe neurological diseases. We discuss the clinical relevance of these viruses and the primary role of humoral immunity in controlling them, and summarize current knowledge on the neutralization of such viruses by antibodies.

Human parechovirus type 3 infection: An emerging infection in neonates and young infants

Human parechoviruses (HPeVs) are RNA viruses that have characteristics similar to those of enteroviruses and usually cause mild respiratory or gastrointestinal symptoms. Human parechovirus type 3 (HPeV3), first reported in 2004, is exceptional because it can provoke sepsis and meningoencephalitis leading to neurological sequelae, and even death, in neonates and young infants. Pediatricians and researchers are increasingly aware that HPeV3 is responsible for serious disease in neonates and young infants. Retrospective studies and several reports of epidemics of HPeV3 infection have provided data on epidemiology, clinical symptoms and signs, laboratory findings, and outcomes. However, the pathogenesis of HPeV3 infection remains unclear, which explains the lack of specific antiviral therapy and effective prevention measures. Maternal antibodies are important in protection against severe HPeV3-related disease, and this may be a clue regarding its pathogenesis. HPeV3 epidemics are likely to continue, and because the clinical manifestations of HPeV3 are severe, determining the pathogenesis of HPeV3 infection and establishing specific antiviral therapies are important goals for future research.

Seroepidemiology of human parechovirus types 1, 3, and 6 in Yamagata, Japan, in 2014

To clarify the seroepidemiology of human parechovirus type 1 (HPeV1), 3 and 6, neutralizing antibodies (NT Abs) were measured in 214 serum specimens collected in 2014 in Yamagata, Japan. The seroprevalence against HPeV1 was 100% in all age groups, while that against HPeV3 and HPeV6 was 79.4% and 66.8%, respectively, overall. The geometric mean titers of NT Abs against HPeV1, 3 and 6 were 755.2, 255.0 and 55.9, respectively, overall. Our findings indicate that HPeV1 is the most prevalent HPeV circulating in Yamagata, followed by HPeV3 and HPeV6.

Seropositivity and epidemiology of human parechovirus types 1, 3, and 6 in Japan

Human parechoviruses (HPeVs) mainly infect young children, causing mild gastrointestinal and respiratory diseases; however, HPeV type 3 (HPeV3) causes severe systemic diseases in young infants. To clarify the characteristics of HPeV infections from the aspects of seropositivity and epidemiology, we measured neutralizing antibody titres against HPeVs in individuals of in different age groups and isolated HPeVs from various clinical specimens in Niigata, Japan. The seropositivity to HPeV1, 3, and 6 was higher in older age group. HPeV1 and HPeV6 seropositivities were maintained in adults, whereas HPeV3 seropositivity was significantly lower in subjects aged >40 years (P < 0·001, P = 0·003). This result suggests that adults have increased susceptibility to HPeV3 as they lack neutralizing antibodies against HPeV3. Of the HPeV isolates, HPeV1 and HPeV6 frequently caused gastrointestinal symptoms. Moreover, gastroenteritis patients with HPeV1 and HPeV6 were mainly aged 6 months-1 year and ⩾2 years, respectively. In contrast, only HPeV3 was isolated from neonates and young infants with sepsis or sepsis-like syndrome, often with respiratory symptoms. These results suggest that clinical symptoms are clinically related to HPeV genotype and patients' age.