The incidence of human bocavirus infection among children admitted to hospital in Singapore

Human bocavirus-1 screening in infants with acute lower respiratory tract infection

Background

Recent studies have reported associations between, human bocavirus (HBoV), and respiratory tract diseases in children. However, there is limited information on the epidemiology of HBoV in infants. This prospective study investigated the prevalence and clinical characteristics of HBoV infection in infants with acute lower respiratory tract infection (ALRTI) in eastern China.

Methods

Nasopharyngeal aspirates and throat swab samples were collected from infants with ALRTI and age-matched healthy infants between January 2016 and December 2019. HBoV was identified by polymerase chain reaction. Laboratory data and clinical characteristics were analyzed.

Results

Of 2510 infants, 145 tested positive for HBoV. The highest prevalence of HBoV was detected during the winter. Co-infection was frequently observed during this period of high viral transmission. There were no HBoV-positive infants in the control group. Clinical signs and symptoms included cough, wheezing, fever, nasal discharge, vomiting, diarrhea, hypoxemia, and tachypnea. Co-infections included: Streptococcus pneumoniae, Staphylococcus aureus, Mycoplasma pneumoniae, Chlamydophila pneumoniae, respiratory syncytial virus, and adenovirus.

Conclusions

HBoV was frequently detected in infants with ALRTI in China. The prevalence of HBoV was highest in winter. Co-infection was common, especially in infants requiring intensive care unit admission. Comprehensive clinical evaluation may facilitate optimal treatment.

Etiology of febrile respiratory infections in the general adult population in Singapore, 2007-2013

Pathogens that cause upper respiratory infections are numerous and specific preventive and therapeutic strategies are scarce. In order to ascertain the etiological agents resulting in upper respiratory tract infections (URTI) in adults in Singapore, nasal swab samples were collected from 2057 patients presenting with fever at primary healthcare clinics in Singapore from December 2007 to February 2013. Samples were tested using the Luminex NxTAG Respiratory Pathogen Panel that includes 22 respiratory pathogen targets. Patient-reported symptoms and vital signs were recorded and full blood and differential counts taken. Pathogens were detected in the following order of frequency: influenza viruses, rhino-/enteroviruses, coronaviruses, parainfluenza viruses, pneumoviruses, adenovirus, bocavirus and C. pneumoniae. Fifteen virus species were detected as part of coinfections, in which rhinoviruses were the most commonly observed pathogen. Our results suggest that influenza viruses are the main etiological agents, but multiple other respiratory viruses contribute to the total burden of URTI in adults in Singapore.

Molecular epidemiology of respiratory viruses among Malaysian Young children with a confirmed respiratory infection during 2014-2015

BACKGROUND

In many developing countries, acute respiratory tract infections (ARTIs) are the main cause of morbidity and mortality among young children. This study aims to evaluate the molecular epidemiology of respiratory viruses among Malaysian children with confirmed respiratory infections between July 2014 and July 2015.

METHODS

A total of 394 nasopharyngeal swabs were collected prospectively from children age 0-5 years old with ARTIs from hospitals in Kuala Lumpur. Respiratory viral panel (RVP) assay was used to identify the viral aetiology of respiratory infections.

RESULTS

From a total of 394 samples, the positive detection rate was 79.9% (n=315). A total of 15 types of RNA viruses and a single type of DNA virus were detected. Enterovirus/rhinovirus (n=112, 28.4%), respiratory syncytial virus (RSV) (n=85, 21.6%), adenovirus (n=64, 16.2%), human bocavirus (n=34, 8.6%), and human metapneumovirus (n=29, 7.4%) were the five predominant viruses. Enterovirus/rhinovirus and RSV constituted most of the viral respiratory infections among young children, especially among children less than 1 year old. No coronavirus was detected among children between 3 and 5 years old. Co-infection caused by 2 or 3 respiratory viruses were detected in 52 patients (13.2%). Enterovirus/rhinovirus, adenovirus, and human bocavirus demonstrated pronounced seasonality. The infection rate peaked during mid-year, while the lowest activity occurred during early of the year.

CONCLUSIONS

The use of molecular assay as a routine diagnostic in the hospitals can improve the diagnosis and management of respiratory tract infections among children.

The Role of the Human Bocavirus (HBoV) in Respiratory Infections

The human bocavirus is one of the most common respiratory viruses and occurs in all age groups. Because Koch’s postulates have been fulfilled unintendedly, it is currently accepted that the virus is a real pathogen associated with upper and lower respiratory tract infections causing clinical symptoms ranging from a mild common cold to life-threatening respiratory diseases. In order to exclude a viremia, serological analysis should be included during laboratory diagnostics, as acute and chronic infections cannot be differentiated by detection of viral nucleic acids in respiratory specimen alone due to prolonged viral shedding. Besides its ability to persist, the virus appears to trigger chronic lung disease and increases clinical symptoms by causing fibrotic lung diseases. Due to the lack of an animal model, clinical trials remain the major method for studying the long-term effects of HBoV infections.

Does Viral Co-Infection Influence the Severity of Acute Respiratory Infection in Children?

Background

Multiple viruses are often detected in children with respiratory infection but the significance of co-infection in pathogenesis, severity and outcome is unclear.

Objectives

To correlate the presence of viral co-infection with clinical phenotype in children admitted with acute respiratory infections (ARI).

Methods

We collected detailed clinical information on severity for children admitted with ARI as part of a Spanish prospective multicenter study (GENDRES network) between 2011–2013. A nested polymerase chain reaction (PCR) approach was used to detect respiratory viruses in respiratory secretions. Findings were compared to an independent cohort collected in the UK.

Results

204 children were recruited in the main cohort and 97 in the replication cohort. The number of detected viruses did not correlate with any markers of severity. However, bacterial superinfection was associated with increased severity (OR: 4.356; P-value = 0.005), PICU admission (OR: 3.342; P-value = 0.006), higher clinical score (1.988; P-value = 0.002) respiratory support requirement (OR: 7.484; P-value < 0.001) and longer hospital length of stay (OR: 1.468; P-value < 0.001). In addition, pneumococcal vaccination was found to be a protective factor in terms of degree of respiratory distress (OR: 2.917; P-value = 0.035), PICU admission (OR: 0.301; P-value = 0.011), lower clinical score (-1.499; P-value = 0.021) respiratory support requirement (OR: 0.324; P-value = 0.016) and oxygen necessity (OR: 0.328; P-value = 0.001). All these findings were replicated in the UK cohort.

Conclusion

The presence of more than one virus in hospitalized children with ARI is very frequent but it does not seem to have a major clinical impact in terms of severity. However bacterial superinfection increases the severity of the disease course. On the contrary, pneumococcal vaccination plays a protective role.

Respiratory infections of the human bocavirus

The human bocavirus is one of the most common respiratory viruses and occurs in all age groups. It is associated with upper and lower respiratory tract infections, and causes clinical symptoms from the mild common cold to life threatening respiratory diseases. Besides its ability to persist the virus appears to trigger chronic lung disease and increase the clinical symptoms, while being a putative trigger for fibrotic lung diseases.

Laboratory diagnostics should include serological diagnostics in order to rule out a viremia because due to prolonged viral shedding acute and chronic infections cannot be differentiated on the detection of viral nucleic acids in respiratory specimen alone.

Although Koch’s postulates cannot be formally fulfilled due to the lack of an animal model and the chance for clinical trials with volunteers are limited due to the long term effects of HBoV infections, there is no doubt that the virus is a serious pathogen and requires attention.

The aim of the chapter is to present an overview of our current knowledge on respiratory infections with the human bocavirus, and to provide basic and essential information on clinical features, molecular diagnostics, and epidemiologic challenges arising with this pathogen.

Viral Co-Infections in Pediatric Patients Hospitalized with Lower Tract Acute Respiratory Infections

BACKGROUND

Molecular techniques can often reveal a broader range of pathogens in respiratory infections. We aim to investigate the prevalence and age pattern of viral co-infection in children hospitalized with lower tract acute respiratory infection (LT-ARI), using molecular techniques.

METHODS

A nested polymerase chain reaction approach was used to detect Influenza (A, B), metapneumovirus, respiratory syncytial virus (RSV), parainfluenza (1-4), rhinovirus, adenovirus (A-F), bocavirus and coronaviruses (NL63, 229E, OC43) in respiratory samples of children with acute respiratory infection prospectively admitted to any of the GENDRES network hospitals between 2011-2013. The results were corroborated in an independent cohort collected in the UK.

RESULTS

A total of 204 and 97 nasopharyngeal samples were collected in the GENDRES and UK cohorts, respectively. In both cohorts, RSV was the most frequent pathogen (52.9% and 36.1% of the cohorts, respectively). Co-infection with multiple viruses was found in 92 samples (45.1%) and 29 samples (29.9%), respectively; this was most frequent in the 12-24 months age group. The most frequently observed co-infection patterns were RSV-Rhinovirus (23 patients, 11.3%, GENDRES cohort) and RSV-bocavirus / bocavirus-influenza (5 patients, 5.2%, UK cohort).

CONCLUSION

The presence of more than one virus in pediatric patients admitted to hospital with LT-ARI is very frequent and seems to peak at 12-24 months of age. The clinical significance of these findings is unclear but should warrant further analysis.

Human bocavirus amongst an all-ages population hospitalised with acute lower respiratory infections in Cambodia

BACKGROUND

Human bocavirus (HBoV) is a novel parvovirus that is associated with respiratory and gastrointestinal tract disease.

OBJECTIVES

To investigate the prevalence and genetic diversity of HBoV amongst hospitalized patients with acute lower respiratory infection (ALRI) in Cambodia.

STUDY DESIGN

  Samples were collected from 2773 patients of all ages hospitalised with symptoms of ALRI between 2007 and 2009. All samples were screened by multiplex RT-PCR/PCR for 18 respiratory viruses. All samples positive for HBoV were sequenced and included in this study.

RESULTS

Of the samples tested, 43 (1·5%) were positive for HBoV. The incidence of HBoV did not vary between the consecutive seasons investigated, and HBoV infections were detected year-round. The incidence of HBoV infection was highest in patients aged < 2 years, with pneumonia or bronchopneumonia the most common clinical diagnosis, regardless of age. A total of 19 patients (44%) were co-infected with HBoV and an additional respiratory pathogen. All isolates were classified as HBoV type 1 (HBoV-1). High conservation between Cambodian NP1 and V1V2 gene sequences was observed.

CONCLUSIONS

Human bocavirus infection can result in serious illness, however is frequently detected in the context of viral co-infection. Specific studies are required to further understand the true pathogenesis of HBoV in the context of severe respiratory illness.

Epidemiology and seasonality of respiratory viral infections in hospitalized children in Kuala Lumpur, Malaysia: a retrospective study of 27 years

Background

Viral respiratory tract infections (RTI) are relatively understudied in Southeast Asian tropical countries. In temperate countries, seasonal activity of respiratory viruses has been reported, particularly in association with temperature, while inconsistent correlation of respiratory viral activity with humidity and rain is found in tropical countries. A retrospective study was performed from 1982-2008 to investigate the viral etiology of children (≤ 5 years old) admitted with RTI in a tertiary hospital in Kuala Lumpur, Malaysia.

Methods

A total of 10269 respiratory samples from all children ≤ 5 years old received at the hospital's diagnostic virology laboratory between 1982-2008 were included in the study. Immunofluorescence staining (for respiratory syncytial virus (RSV), influenza A and B, parainfluenza types 1-3, and adenovirus) and virus isolation were performed. The yearly hospitalization rates and annual patterns of laboratory-confirmed viral RTIs were determined. Univariate ANOVA was used to analyse the demographic parameters of cases. Multiple regression and Spearman's rank correlation were used to analyse the correlation between RSV cases and meteorological parameters.

Results

A total of 2708 cases were laboratory-confirmed using immunofluorescence assays and viral cultures, with the most commonly detected being RSV (1913, 70.6%), parainfluenza viruses (357, 13.2%), influenza viruses (297, 11.0%), and adenovirus (141, 5.2%). Children infected with RSV were significantly younger, and children infected with influenza viruses were significantly older. The four main viruses caused disease throughout the year, with a seasonal peak observed for RSV in September-December. Monthly RSV cases were directly correlated with rain days, and inversely correlated with relative humidity and temperature.

Conclusion

Viral RTIs, particularly due to RSV, are commonly detected in respiratory samples from hospitalized children in Kuala Lumpur, Malaysia. As in temperate countries, RSV infection in tropical Malaysia also caused seasonal yearly epidemics, and this has implications for prophylaxis and vaccination programmes.

Does human bocavirus infection depend on helper viruses? A challenging case report

A case of severe diarrhoea associated with synergistic human bocavirus type 1 (HBoV) and human herpes virus type 6 (HHV6) is reported. The case supports the hypotheses that HBoV infection under clinical conditions may depend on helper viruses, or that HBoV replicates by a mechanism that is atypical for parvoviruses, or that HBoV infection can be specifically treated with cidofovir.

Human bocavirus as an important cause of respiratory tract infection in Taiwanese children

BACKGROUND

Human bocavirus (HBoV), first described in September 2005, was considered a causative agent of previously unexplained respiratory tract diseases. However, only few reports provide the evidence for an association between HBoV and respiratory tract diseases. We conducted a prospective clinical and molecular study of HBoV in Taiwan.

METHODS

We enrolled 705 children who visited our outpatient pediatric clinics in a medical center because of symptoms and signs of respiratory tract infections from November 2008 to October 2009. Throat swab was performed and HBoV polymerase chain reaction and viral culture were done simultaneously.

RESULTS

Positive viral results were confirmed in 159 (22.6%) of the 705 children. HBoV was found in 35 samples and it was supposed to be as a single virus in 32 samples because viral isolation of these 32 samples did not identify other virus. The other three patients had coinfection with another virus. One child got HBoV reinfection 6 months after the first infection. Seventy-one percentage of these HBoV infections occurred between November and March. Of the 34 children with positive HBoV, 26 (76%) patients were younger than 5 years; their common symptoms were cough, rhinorrhea, and fever; the most common diagnoses were bronchitis (34%, 12/35) and sinusitis (31%, 11/35) followed by pharyngitis (29%, 10/35) and asthma exacerbation (26%, 9/35). Three of the 34 patients needed hospitalization.

CONCLUSION

HBoV is an emerging human parvovirus that may cause respiratory tract infection in young children. Diseases associated with HBoV may range from pharyngitis, sinusitis, acute otitis media to bronchitis, asthma, and even pneumonia.

Correlation between bocavirus infection and humoral response, and co-infection with other respiratory viruses in children with acute respiratory infection

BACKGROUND

Human bocavirus (HBoV), a recently discovered virus, is prevalent among children with respiratory tract infection throughout the world. Co-infection was frequently found in HBoV-positive patients. Thus, whether HBoV is responsible for the respiratory disease is still arguable.

OBJECTIVES

A comprehensive study was carried out to integrate clinical and virological prevalence in HBoV-positive outpatient children, and to determine genetic and serologic characteristics of HBoV in Shanghai, China.

STUDY DESIGN

Nasal/throat swabs and sera were obtained over a 2-year period from 817 children with respiratory tract infection to examine the presence of HBoV and its co-infection. The seroepidemiology of HBoV was studied by ELISA and Western blot against the capsid protein VP2-based fragment. Persistence of HBoV was also analyzed in 12 pairs of return-visit cases.

RESULTS

HBoV was identified in 96 samples (11.8%). The co-infection rate with other respiratory viruses was 51%. IgM was detected in 55.7% of HBoV RT-PCR-positive patients, and in 72.7% of those who had high viral genome load. In addition, persistent viral DNA positivity was detected in 10 of 12 HBoV-positive cases tested, an average of 14 days later, and one child was still HBoV-positive after 31 days.

CONCLUSION

HBoV was found frequently in children with respiratory tract symptoms associated with other respiratory viruses, and persisted in the respiratory tract and in serum and urine. The presence of IgM was significantly more prevalent in viremic patients and those diagnosed with high load of HBoV DNA in nasal/throat swabs.

Human bocavirus infection in young children with acute respiratory tract infection in Lanzhou, China

Human bocavirus (HBoV) is a recognized human parvovirus associated with acute respiratory tract infection. However, HBoV has yet to be established as a causative agent of respiratory disease. In this study, the epidemiological and virological characteristics of HBoV infection were studied in children with acute respiratory tract infection in China. In total, 406 children younger than 14 years of age with acute respiratory tract infection were included in this prospective 1-year study. HBoV was detected in 29 (7.1%) of the 406 children. No clear seasonal fluctuation was observed in infection rates of HBoV. Of the 29 children infected with HBoV, 16 (55.2%) were coinfected with other respiratory viruses, most commonly respiratory syncytial virus (RSV). Viral coinfection with HBoV did not affect the severity of the respiratory disease (P = 0.291). The number of HBoV genome copies ranged from 5.80 x 10(2) to 9.72 x 10(8) copies/ml in nasopharyngeal aspirates among HBoV-positive specimens by real-time PCR, and neither coinfection nor the severity of disease correlated with the viral load (P = 0.148, P = 0.354, respectively). The most common clinical features were cough and acute upper respiratory infection, and acute bronchopneumonia. Additionally, the NP-1 gene of HBoV showed minimal sequence variation. These data suggest that HBoV is frequent in young children with acute respiratory tract infection in Lanzhou, China, and RSV is the most common coinfecting virus. There was no apparent association between the viral load of HBoV and coinfection or disease severity. The NP-1 gene was highly conserved in HBoV.

Human bocavirus infections in hospitalized Greek children

INTRODUCTION

The epidemiology of human bocavirus (HBoV) infections has not been described in Greece, a south-eastern European country. To define the epidemiological profile and the clinical characteristics associated with HBoV infection in a population of children hospitalized with respiratory tract infection.

MATERIAL AND METHODS

During a one-year period throat swab samples were collected from 370 previously healthy children, aged 14 days to 13 years, admitted to two different paediatric wards because of respiratory tract infection. Samples were tested for HBoV by PCR amplifying a part of the NS1 gene.

RESULTS

Human bocavirus was detected in 12 children (3.2%). Four of the 12 cases were co-infections, 3 of them with influenza A and 1 with coronavirus OC43. Cases were observed only during the cold months. The mean age of children was 1.8 years (range 2 months to 4 years). The most common symptoms were fever, cough and various degrees of respiratory distress. All children were clinically diagnosed as having lower respiratory tract infections, mainly pneumonia and acute laryngotracheobronchitis, and recovered uneventfully.

CONCLUSIONS

HBoV infections occur in Greece mostly among very young children. They accounted for 3.2% of children hospitalized with acute respiratory disease. Cases were observed only in late autumn to early spring.

Evidence of recombination and genetic diversity in human rhinoviruses in children with acute respiratory infection

Background

Human rhinoviruses (HRVs) are a highly prevalent cause of acute respiratory infection in children. They are classified into at least three species, HRV-A, HRV-B and HRV-C, which are characterized by sequencing the 5′ untranslated region (UTR) or the VP4/VP2 region of the genome. Given the increased interest for novel HRV strain identification and their worldwide distribution, we have carried out clinical and molecular diagnosis of HRV strains in a 2-year study of children with acute respiratory infection visiting one district hospital in Shanghai.

Methodology/Findings

We cloned and sequenced a 924-nt fragment that covered part of the 5′UTR and the VP4/VP2 capsid genes. Sixty-four HRV-infected outpatients were diagnosed amongst 827 children with acute low respiratory tract infection. Two samples were co-infected with HRV-A and HRV-B or HRV-C. By comparative analysis of the VP4/VP2 sequences of the 66 HRVs, we showed a high diversity of strains in HRV-A and HRV-B species, and a prevalence of 51.5% of strains that belonged to the recently identified HRV-C species. When analyzing a fragment of the 5′ UTR, we characterized at least two subspecies of HRV-C: HRV-Cc, which clustered differently from HRV-A and HRV-B, and HRV-Ca, which resulted from previous recombination in this region with sequences related to HRV-A. The full-length sequence of one strain of each HRV-Ca and HRV-Cc subspecies was obtained for comparative analysis. We confirmed the close relationship of their structural proteins but showed apparent additional recombination events in the 2A gene and 3′UTR of the HRV-Ca strain. Double or triple infections with HRV-C and respiratory syncytial virus and/or bocavirus were diagnosed in 33.3% of the HRV-infected patients, but no correlation with severity of clinical outcome was observed.

Conclusion

Our study showed a high diversity of HRV strains that cause bronchitis and pneumonia in children. A predominance of HRV-C over HRV-A and HRV-B was observed, and two subspecies of HRV-C were identified, the diversity of which seemed to be related to recombination with former HRV-A strains. None of the HRV-C strains appeared to have a higher clinical impact than HRV-A or HRV-B on respiratory compromise.

Low prevalence of human metapneumovirus and human bocavirus in adult immunocompromised high risk patients suspected to suffer from Pneumocystis pneumonia

BACKGROUND

Novel respiratory viruses were discovered in the last years predominantly in children. Until now information on newly identified respiratory viruses in immunosuppressed adult patients is limited. Here we investigated immunocompromised adults with suspected Pneumocystis jirovecii pneumonia (PCP) for new respiratory viruses.

METHODS

Bronchoalveolar lavage (BAL) samples of 128 patients with atypical pneumonia (HIV-infected n=50, hematological malignancy n=51, immunosuppressive treatment n=27) were prospectively evaluated for P. jirovecii and retrospectively for new respiratory viruses (HMPV, HBoV, HCoV-NL63/SARS/HKU1).

RESULTS

P. jirovecii was detected in 26/128, bacteria in 10, fungi in four, Influenza A in two patients. Novel respiratory viruses were found in only two/128 patients with hematological malignancy, of those one patient with HBoV-infection and one with HMPV-infection, respectively. No pathogens were detected in 82/128 patients. The one patient with detection of hMPV and clinical diagnosis of atypical pneumonia died of pulmonary failure.

CONCLUSION

Human bocavirus and human metapneumovirus are rarely involved in atypical pneumonia in immunocompromised adult patients with suspected PCP, but may contribute to severe respiratory failure.