Clinical and epidemiological profiles of lower respiratory tract infection in hospitalized children due to human bocavirus in a subtropical area of China

Clinical and molecular characterization of children and adults with respiratory bocavirus infection in Mexico: a cross-sectional nested study within the ILI002 prospective observational study

Background

Human Bocaviruses (HBoV) can cause acute respiratory tract infections. High coinfection rates cloud its pathogenicity. This study sought to describe the clinical features of HBoV1 disease in children and adults with Influenza-like illness (ILI), exploring associations between viral load, clinical features, and seasonality.

Methods

Patients who tested positive for HBoV1 by polymerase chain reaction, enrolled from April 2010 to March 2014 in the ILI002 prospective observational cohort study were included in this cross-sectional nested study. Participants were included in ILI002 if they presented with signs and/or symptoms suggestive of influenza-like illness. Samples were tested for viral load, and NP1 and VP1/VP2 phylogenetic analyses, except for the samples lacking suitable and viable clinical material for genotyping.

Findings

We identified HBoV1 in 157 (2.8%) of participants. Prevalence was 4.5% in children and 1.8% in adults. Single HBoV1 detection occurred in 41.1% and 46.3% of children and adults, respectively. Children commonly experienced fever (83.3%), cough with sputum (74.4%), and shortness of breath (72.2%). In the multivariate analysis of children, significant positive associations were detected between viral loads and age (0.20 [95% CI: 0.07, 0.33]), and the presence of fever (2.64 [95% CI: 1.35, 3.94]), nasal congestion (1.03 [95% CI: 0.07, 1.99]), dry cough (1.32 [95% CI: 0.42, 2.22]), chest congestion (1.57 [95% CI: 0.33, 2.80]), red eyes (1.25 [95% CI: 0.35, 2.14]), cough with sputum (1.79 [95% CI: 0.80, 2.78]), and other signs and symptoms such as chills, dizziness, and diaphoresis (1.73 [95% CI: 0.19, 3.27]). In contrast, significant negative associations were found between viral loads and percent neutrophils on the blood count (-0.04 [95% CI: -0.06, -0.02]), fatigue (-1.60 [95% CI: -2.46, -0.74]) and the presence of other symptoms or signs, including adenopathy and rash (-1.26 [95% CI: -2.31, -0.21]). Adults commonly experienced sore throat (73.1%), fatigue (77.4%), and headache (73.1%). In the multivariate analysis of adults, significant positive associations were detected between viral load and body mass index (0.13 [95% CI: 0.04, 0.21]), and the presence of confusion (1.54 [95% CI: 0.55, 2.53]), and sore throat (1.03 [95% CI: 0.20, 1.85]), and significant negative associations were detected between viral load and chest congestion (-1.16 [95% CI: -2.07, -0.24]). HBoV1 was detected throughout the year irrespective of season, temperature, and humidity.

Interpretation

This study demonstrated the importance of detecting HBoV1 in patients with influenza-like illness either as single infection or co-infection, in both adults and children, and improves the characterization of HBoV1 seasonality, clinical features, and viral load. Phylogenetic analyses show a high conservation.

Funding

The Mexican Emerging Infectious Diseases Clinical Research Network (LaRed), CONACYT (Fondo Sectorial SSA/IMSS/ISSSTE, Projects No. 71260 and No. 127088), Fondos federales no. HIM/2015/006, NIAID, NIH through a contract with Westat, Inc. (HHSN2722009000031, HHSN27200002), NCI, NIH (75N91019D00024, 75N91019F00130). Additional information at the end of the manuscript.

Epidemiology of HBoV1 infection and relationship with meteorological conditions in hospitalized pediatric patients with acute respiratory illness: a 7-year study in a subtropical region

BACKGROUND

Human bocavirus 1 (HBoV1) is an important cause of acute respiratory illness (ARI), yet the epidemiology and effect of meteorological conditions on infection is not fully understood. To investigate the distribution of HBoV1 and determine the effect of meteorological conditions, hospitalized pediatric patients were studied in a subtropical region of China.

METHODS

Samples from 11,399 hospitalized pediatric patients (≤14 years old), with ARI were tested for HBoV1 and other common respiratory pathogens using real-time PCR, between July 2009 and June 2016. In addition, local meteorological data were collected.

RESULTS

Of the 11,399 patients tested, 5606 (49.2%) were positive for at least one respiratory pathogen. Two hundred forty-eight of 11,399 (2.2%) were positive for HBoV1 infection. Co-infection was common in HBoV1-positive patients (45.2%, 112/248). A significant difference in the prevalence of HBoV1 was found in patients in different age groups (p < 0.001), and the peak prevalence was found in patients aged 7-12 months (4.7%, 56/1203). Two HBoV1 prevalence peaks were found in summer (between June and September) and winter (between November and December). The prevalence of HBoV1 was significantly positively correlated with mean temperature and negatively correlated with mean relative humidity, and the mean temperature in the preceding month had better explanatory power than the current monthly temperature.

CONCLUSIONS

This study provides a better understanding of the characteristics of HBoV1 infection in children in subtropical regions. Data from this study provide useful information for the future control and prevention of HBoV1 infections.

The role of granulocyte macrophage colony stimulating factor in hospitalized children with Mycoplasma pneumoniae pneumonia

BACKGROUND

Inappropriate inflammatory response in children with M. pneumoniae infection might be associated with disease severity. The role of Granulocyte macrophage colony stimulating factor (GM-CSF) in hospitalized children with Mycoplasma pneumoniae pneumonia (MPP) has not been fully discussed.

METHODS

Clinical and laboratory data of a total 40 children with MPP were collected. GM-CSF and myeloperoxidase (MPO) were detected by ELISAs. Meanwhile, normal human bronchial epithelium was infected by M. pneumoniae and neutrophils were stimulated by GM-CSF to explore GM-CSF and MPO release in supernatant, respectively.

RESULTS

Compared to control group, a significant increased percentage of neutrophils and decreased percentage of macrophages in bronchoalveolar lavage fluid of children with MPP was observed (P < 0.05). Children with MPP had significantly higher levels of GM-CSF (P = 0.0047) and MPO (P = 0.0002) in BALF compared to the controls. Level of GM-CSF in BALF was associated with duration of fever (r = 0.42, P = 0.007) and strongly correlated with level of MPO (r = 0.075, P = 0.0005). Levels of GM-CSF and MPO significantly decreased (both P < 0.05) after treatment. In vitro, M. pneumoniae induced GM-CSF expression in a time-dependent manner during a 72-h period (P < 0.05) and MPO secretion significantly increased by recombinant human GM-CSF stimulation at 24h (P < 0.05).

CONCLUSION

GM-CSF could be induced by M. pneumoniae infection in vivo and vitro. Childen with high level GM-CSF had longer duration of fever. GM-CSF probably plays a vital role in neutrophil inflammation in M. pneumoniae infection.

Viral aetiology of wheezing in children under five

Background & objectives:

Wheezing is a common problem in children under five with acute respiratory infections (ARIs). Viruses are known to be responsible for a considerable proportion of ARIs in children. This study was undertaken to know the viral aetiology of wheezing among the children less than five years of age, admitted to a tertiary care hospital in eastern India.

Methods:

Seventy five children, under the age of five years admitted with wheezing, were included in the study. Throat and nasal swabs were collected, and real-time multiplex polymerase chain reaction (PCR) assay was used to screen for influenza 1 and 2, respiratory syncytial virus (RSV), parainfluenza virus (PIV) 1, 2, 3 and 4, rhinovirus, human meta-pneumovirus, bocavirus (HBoV), Coronavirus, adenovirus, Enterovirus and Parechovirus.

Results:

The total viral detection rate was 28.57 per cent. Viral RNA markers were detected from children diagnosed to be having pneumonia (3 cases), bronchiolitis (9 cases), episodic wheeze (2 cases) and multitrigger wheeze (6 cases). RSV was the most common virus (35%) followed by PIV1, 2 and 3 (20%), HBoV (10%) and rhinovirus (5%). However, mixed infection was observed in 30 per cent of cases.

Interpretation & conclusions:

The study reported the presence of respiratory viral agents in 28.57 per cent of children with wheezing; RSV and PIV were most common, accounting to 55 per cent of the total cases. Mixed infection was reported in 30 per cent of cases. Seasonal variation in the occurrence of these viruses was also noted. Further studies need to be done with a large sample and longer follow up period to verify these findings.

Pediatric clinical features of Mycoplasma pneumoniae infection are associated with bacterial P1 genotype

The present study evaluated the association between different Mycoplasma pneumoniae (M. pneumonia) genotypes and clinical features of pediatric patients. Subjects were children diagnosed with community-acquired pneumonia at the Children's Hospital of Soochow University (Suzhou, China) from January 2012 to December 2013. Clinical and laboratory tests were conducted and clinical samples positive for M. pneumoniae were genotyped by nested-multiplex polymerase chain reaction. Three type I strains and three type II strains were also randomly selected for sequencing. A total of 335 clinical samples positive for M. pneumoniae were obtained. The average age of M. pneumonia-infected pediatric patients was 4.8±3.3 (years). Genotyping results identified 304 positive samples as group I strains and 30 samples as group II strains, in which 1 sample was type II variant 2a. It was also observed that point mutations were more likely to occur in type I strains compared with type II strains. Although clinical pulmonary infection scores between patients with type I and type II strains did not significantly differ, patients with type I strains had a higher risk of developing severe M. pneumoniae pneumonia (SMPP) and extrapulmonary complications, and had significantly higher percentages of peripheral blood neutrophils than patients with type II strains (P<0.05). Collectively, these data indicate that the predominant strains of M. pneumoniae in Suzhou between 2012 and 2013 were type I, and that pediatric pneumonia patients with type I strains of M. pneumoniae were more likely to progress to SMPP.

Increased concentrations of soluble B7-H3 and interleukin 36 in bronchoalveolar lavage fluid of Children with Mycoplasma pneumoniae pneumonia

Background

The purpose of this study is to explore the correlations of interleukin 36 (IL-36) and Soluble B7-H3 (sB7-H3) levels in bronchoalveolar lavage fluid (BALF) with clinical characteristics and laboratory findings.

Methods

A total of 35 children with M. pneumnoiae pneumonia (MPP) and 15 control subjects were enrolled. BALF concentrations of sB7-H3 and IL-36 were detected using enzyme-linked immunosorbent assays and clinical profiles of children with MPP were obtained.

Results

Children with MPP had significantly higher levels of sB7-H3 and IL-36 compared to control subjects (both P < 0.05). Meanwhile, children with pleural effusion had significantly higher levels of sB7-H3 and IL-36 compared to children without pleural effusion (both P < 0.05). BALF concentration of sB7-H3 was strongly associated with concentration of IL-36 (r = 0.796, P < 0.0001) and sB7-H3 was correlated with duration of fever (r = 0.427, P = 0.11) and length of stay (r = 0.345, P = 0.043). Both concentrations of sB7-H3 and IL-36 were significantly decreased in convalescent phase after treatment (both P < 0.05).

Conclusion

Both soluble B7-H3 and IL-36 may play an important role in pathogenesis of M. pneumoniae infection and sB7-H3 could be useful as a prognostic predictor or biomarker of MPP.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1555-6) contains supplementary material, which is available to authorized users.

Role of the Mycoplasma pneumoniae/Interleukin-8/Neutrophil Axis in the Pathogenesis of Pneumonia

Neutrophil infiltration is the characteristic pathological feature of M. pneumoniae pneumonia (MPP). This study aimed to explore the associations among neutrophil activity, clinical presentation, and role of the M. pneumoniae/interleukin-8 (IL-8)/neutrophil axis in the pathogenesis of MPP. A total of 42 patients with MPP were prospectively enrolled in the study. Neutrophil activity, including matrix metalloproteinase-9 (MMP-9), myeloperoxidase (MPO), and neutrophil elastase (NE), were measured. Clinical information was collected for all patients and control group. In vitro, IL-8 production was measured at different time points after M. pneumoniae infection of bronchial epithelial cells, and neutrophil activity was analyzed after IL-8 stimulation. The percentage of neutrophil in the bronchoalveolar lavage fluid was higher in the group of patients with high levels of M. pneumoniae DNA than in those with low levels of M. pneumoniae DNA (P < 0.05). IL-8, MMP-9, and NE in patients with MPP significantly increased compared with controls and decreased after treatment (P < 0.05). MPO and MMP-9 were associated with duration of fever (r = 0.332, P < 0.05) and length of stay (r = 0.342, P < 0.05), respectively. In vitro, M. pneumoniae induced IL-8 production by bronchial epithelial cells in a time dependent manner. MPO, MMP-9 and NE production by neutrophils significantly increased compared with medium controls after IL-8 stimulation. In summary, the M. pneumoniae/IL-8/neutrophil axis likely plays a vital role in the pathogenesis of MPP.

Atypical presentation of human bocavirus: Severe respiratory tract infection complicated with encephalopathy

Human bocavirus (HBOV) has been reported as a worldwide distributed respiratory pathogen. It has also been associated with encephalitis recently by detection of the virus in cerebrospinal fluid (CSF) of patients presented with encephalitis. This retrospective study aimed to present clinical features of HBOV infections in children with respiratory symptoms and describe unexplained encephalopathy in a subgroup of these patients. Results of 1,143 pediatric nasal samples from mid-December 2013 to July 2014 were reviewed for detection of HBOV. A multiplex real time polymerase chain reaction assay was used for viral detection. Medical records of the patients were retrospectively analyzed. HBOV was detected in 30 patients (2.6%). Median age was 14 months (5-80). Clinical diagnoses were upper respiratory tract infection (n = 10), bronchopneumonia (n = 9), acute bronchiolitis (n = 5), pneumonia (n = 4), acute bronchitis (n = 1), and asthma execarbation (n = 1). Hospitalization was required in 16 (53.3%) patients and 10 (62.5%) of them admitted to pediatric intensive care unit (PICU). Noninvasive mechanical ventilation modalities was applied to four patients and mechanical ventilation to four patients. Intractable seizures developed in four patients while mechanically ventilated on the 2nd-3rd days of PICU admission. No specific reason for encephalopathy was found after a thorough investigation. No mortality was observed, but two patients were discharged with neurological sequela. HBOV may lead to respiratory infections in a wide spectrum of severity. This report indicates its potential to cause severe respiratory infections requiring PICU admission and highlights possible clinical association of HBOV and encephalopathy, which developed during severe respiratory infection.

The Prevalence of Human Bocavirus, Human Coronavirus-NL63, Human Metapneumovirus, Human Polyomavirus KI and WU in Respiratory Tract Infections in Kuwait

OBJECTIVE

The aim of this study was to investigate the prevalence of human coronavirus (HCoV)-NL63, human metapneumovirus (hMPV), human bocavirus (Boca), human polyomavirus KI (KIV) and human polyomavirus WU (WUV) in respiratory tract infections (RTI) in Kuwait.

MATERIALS AND METHODS

Respiratory samples from 735 hospitalized patients with RTI from September 2010 to April 2013 were evaluated for the presence of HCoV-NL63, hMPV, Boca, KIV and WUV using molecular assays, polymerase chain reaction (PCR) and reverse-transcription PCR.

RESULTS

Of the 735 patients, 285 (38.8%) were diagnosed with viral RTI. The distribution of respiratory viruses was hMPV: 15 (5.3%), Boca: 14 (4.9%), WUV: 10 (3.5%) and KIV: 4 (1.4%). HCoV-NL63 was not detected in any of the samples.

CONCLUSIONS

These newly discovered viruses were associated with the development of RTI in Kuwait. The rapid identification of these viral infections could aid in the control of nosocomial transmission, reduce the use of antibiotics and improve treatment and management strategies.

Effects of human Parvovirus B19 and Bocavirus VP1 unique region on tight junction of human airway epithelial A549 cells

As is widely recognized, human parvovirus B19 (B19) and human bocavirus (HBoV) are important human pathogens. Obviously, both VP1 unique region (VP1u) of B19 and HBoV exhibit the secreted phospholipase A2 (sPLA2)-like enzymatic activity and are recognized to participate in the pathogenesis of lower respiratory tract illnesses. However, exactly how, both VP1u from B19 and HBoV affect tight junction has seldom been addressed. Therefore, this study investigates how B19-VP1u and HBoV-VP1u may affect the tight junction of the airway epithelial A549 cells by examining phospholipase A2 activity and transepithelial electrical resistance (TEER) as well as performing immunoblotting analyses. Experimental results indicate that TEER is more significantly decreased in A549 cells by treatment with TNF-α (10 ng), two dosages of B19-VP1u and BoV-VP1u (400 ng and 4000 ng) or bee venom PLA2 (10 ng) than that of the control. Accordingly, more significantly increased claudin-1 and decreased occludin are detected in A549 cells by treatment with TNF-α or both dosages of HBoV-VP1u than that of the control. Additionally, more significantly decreased Na+/K+ ATPase is observed in A549 cells by treatment with TNF-α, high dosage of B19-VP1u or both dosages of BoV-VP1u than that of the control. Above findings suggest that HBoV-VP1u rather than B19 VP1u likely plays more important roles in the disruption of tight junction in the airway tract. Meanwhile, this discrepancy appears not to be associated with the secreted phospholipase A2 (sPLA2)-like enzymatic activity.