Human metapneumovirus infection in young children hospitalized with acute respiratory tract disease: virologic and clinical features

Human metapneumovirus and human bocavirus associated with respiratory infection in Apulian population

We have studied the occurrence of hBoV, hMPV and InfA-B in an Apulian population with respiratory tract infections. During influenza season 2008-2009, 116 oropharingeal swabs were collected from patients affected by Influenza-Like Illness (ILI). The PCR products of hMPV M and HBoV NP-1 genes were sequenced. 78 out of 116 samples were positive for at least one respiratory virus; hBoV was detected in 53, hMPV in 22 and InfA-B in 41 out of 116 swabs. A high rate of hBoV infection in adult (18.9%) and elderly (26.4%) subjects was found. The co-infection rate was higher for hMPV (18/22 cases, 81.8%) compared to hBoV (26/53 cases, 49.1%), and InfA-B (25/41 cases, 61.0%). Co-infections were common in children. hBoV positive samples shared a high level of genetic similarity with the hBoV1 genotype, and hMPV positive samples clustered with A2 subgroup. Our results suggest that hBoV and hMPV play a role in ILI.

The relationship between respiratory viral loads and diagnosis in children presenting to a pediatric hospital emergency department

BACKGROUND

respiratory viral infections account for a considerable proportion of pediatric emergency room visits. Illnesses range in severity from mild upper respiratory tract infections to serious lower respiratory tract infections (LRTI). The relationship between viral load and specific viruses to clinical diagnosis made by physicians in this setting is poorly understood.

METHODS

we applied a real-time, quantitative polymerase chain reaction (qPCR) panel for 13 common respiratory viruses to 195 frozen, archival nasopharyngeal aspirate specimens obtained from symptomatic children ≤ 4 months of age presenting to the emergency room. Mean total viral load and number of viruses per archival nasopharyngeal aspirate specimen were compared between LRTI (n = 70) and non-LRTI (1 or more of upper respiratory tract infection, fever, or cough) (n = 125), as were yield and concordance of qPCR results to viral culture/direct fluorescence assay (DFA).

RESULTS

children with LRTI had significantly increased total viral load and harbored more viruses than the non-LRTI group. Respiratory syncytial virus-A and -B were significantly associated with LRTI, and parainfluenza virus-1 with non-LRTI. Individual loads of parainfluenza virus-2 and human rhinovirus were increased in LRTI versus non-LRTI. Quantitative PCR yielded more viruses (including coinfections, where a "dominant virus" was typically identified) than viral culture/DFA and documented nucleic acid from pathogens not tested by culture/DFA including human rhinovirus; coronaviruses -OC43, -229E, and -NL63; and metapneumovirus.

CONCLUSIONS

in symptomatic children presenting to the emergency room, total viral load is related to clinical diagnosis; specific viruses are associated with particular clinical diagnoses, and qPCR has a higher yield than other viral diagnostic methods.

Viral etiology of acute lower respiratory tract infections in hospitalized young children in Northern Taiwan

BACKGROUND

Lower respiratory tract infections (LRTIs) comprise a great proportion of diagnoses among hospitalized children. This study identifies the viral pathogens causing LRTIs in young children and compares their clinical features and disease severity.

METHODS

Children younger than 36 months old, hospitalized at a medical center in Northern Taiwan with acute bronchiolitis or pneumonia from April to December 2007, were prospectively enrolled. Nasopharyngeal aspiration fluid samples were sent for virus culture, for direct immunofluorescence test of respiratory syncytial virus (RSV), for rapid influenza viral identification, and for polymerase chain reaction of human metapneumovirus (hMPV), human boca virus (hBoV), and human corona virus. The clinical features and laboratory findings were recorded and analyzed.

RESULTS

A total of 48 children were enrolled. RSV was the most common pathogen (41.7%), followed by hMPV (27.1%), hBoV, and enterovirus (both 6.3%). There were no significant differences in clinical presentation and disease severity between the RSV and hMPV groups. However, the hMPV group had a higher mixed infection rate (p = 0.038). Fourteen children had no identifiable viruses. Children with single, dual, and triple pathogens numbered 26, 7, and 1, respectively. The mixed infection rate reached 23.5% among 34 children with identifiable viruses. Children with a higher severity score had greater chance to develop asthma in the next 2 years (p = 0.042).

CONCLUSION

RSV is the most common pathogen causing LRTIs in young children, followed by hMPV. The hMPV group had higher mixed infection rate than RSV group. hBoV does circulate in northern Taiwan.

[Children with cancer and respiratory viral infection: epidemiology, diagnosis and treatment options]

Community-adquired respiratory viral infection is the most common cause of febrile infection in children, and an important cause of infection to consider in children with cancer. Nevertheless, there are few well-designed, controlled studies in this population, which makes it difficult to understand the importance, behaviour and management of these viruses in immunocompromised children. New diagnostic techniques in PCR-based microbiology, could provide many opportunities for early diagnosis, preventing the spread of the virus and to implement the correct therapy. It is important to design appropriate prospective studies to assess these types of infections in children with cancer. In this review we analyse the main studies published in the literature, evaluating the epidemiology, diagnosis and management of children with cancer and respiratory viral infection.

Early life patterns of common infection: a latent class analysis

Early life infection has been implicated in the aetiology of many chronic diseases, most often through proxy measures. Data on ten infectious symptoms were collected by parental questionnaire when children were 6 months old as part of the Avon Longitudinal Study of Parents and Children, United Kingdom. A latent class analysis was used to identify patterns of infection and their relationship to five factors commonly used as proxies: sex, other children in the home, maternal smoking, breastfeeding and maternal education. A total of 10,032 singleton children were included in the analysis. Five classes were identified with differing infectious disease patterns and children were assigned to the class for which they had a highest probability of membership based on their infectious symptom profile: ‘general infection’ (n = 1,252, 12.5%), ‘gastrointestinal’ (n = 1,902, 19.0%), ‘mild respiratory’ (n = 3,560, 35.5%), ‘colds/ear ache’ (n = 462, 4.6%) and ‘healthy’ (n = 2,856, 28.5%). Females had a reduced risk of being in all infectious classes, other children in the home were associated with an increased risk of being in the ‘general infection’, ‘mild respiratory’ or ‘colds/ear ache’ class. Breastfeeding reduced the risk of being in the ‘general infection’ and ‘gastrointestinal’ classes whereas maternal smoking increased the risk of membership. Higher maternal education was associated with an increased risk of being in the ‘mild respiratory’ group. Other children in the home had the greatest association with infectious class membership. Latent class analysis provided a flexible method of investigating the relationship between multiple symptoms and demographic and lifestyle factors.

The distinguishing features of human metapneumovirus and respiratory syncytial virus

Acute respiratory tract infections (RTIs) are a leading cause of morbidity and mortality worldwide. Human Metapneumovirus (hMPV) is a member of the Metapneumovirus genus within the Pneumovirinae subfamily of the Paramyxoviridae family. Though hMPV was only discovered in 2001, a large body of work has already shown that it is the aetiologic agent of a substantial proportion of upper and lower RTIs across all age groups in both healthy and immunocompromised hosts throughout the world. RSV, also a pneumovirus, is the human pathogen most closely related to hMPV. RSV is the leading cause of pneumonia and bronchiolitis in infants and young children, but can also cause respiratory tract disease in all age groups. In this paper, we will review the salient features of the virology, epidemiology, pathogenesis, host immune responses, clinical manifestations and diagnostic modalities of hMPV, using RSV as a comparison. In addition, we will show how immunoprophylactic and therapeutic strategies studied and used in clinical practice for RSV-some with great success, and others tragic failure-have led to promising areas of research for the prevention and treatment of the significant burden of disease caused by hMPV.

Human metapneumovirus and respiratory syncytial virus: subtle differences but comparable severity

Human metapneumovirus (hMPV) is a recently discovered virus that causes respiratory illness in children that can lead to hospitalization. Our study was undertaken to further understand hMPV-associated illness, compare clinical characteristics of hMPV and respiratory syncytial virus (RSV), and establish the utility of routine screening for hMPV. We retrospectively identified hMPV-associated illnesses described among children with respiratory symptoms admitted to a tertiary care center in southeast Michigan during the 2006–2007 respiratory viral season. A convenience sample of 256 nasopharyngeal specimens was subjected to nucleic acid extraction and amplification to identify those specimens positive for hMPV. A medical record review was undertaken to retrieve demographic and clinical data of patients with hMPV, comparing them to RSV-positive patients and patients evaluated for respiratory symptoms who were negative for hMPV and RSV. We found that hMPV was the second most commonly identified virus after RSV. hMPV-positive patients were older than RSV-positive patients. Among hMPV-positive patients, pneumonia was diagnosed in 37.5% and bronchiolitis in 31.2%, peribronchial cuffing was present on chest radiographs of 37.5%, antibiotic treatment was used in 81.2%, and admission to the ICU was seen in 37.5%. Finally, hMPV-positive patients were more likely to have fever than RSV-positive patients or patients negative for hMPV and RSV. We concluded that hMPV is a major pathogen associated with hospitalization of children and with the same severity of illness as RSV but in a slightly older population. Because of the apparent prevalence and severity of illness, routine screening should be implemented.

Comparison of two commercial molecular assays for simultaneous detection of respiratory viruses in clinical samples using two automatic electrophoresis detection systems

Two molecular assays were compared with real-time RT-PCR and viral culture for simultaneous detection of common viruses from respiratory samples: a multiplex ligation-dependant probe amplification (MLPA) and a dual priming oligonucleotide system (DPO). In addition, the positive detections of MLPA and DPO were identified using two different automatic electrophoresis systems. A panel of 168 culture-positive and negative samples was tested by the molecular assays for the presence of influenza A and B virus, respiratory syncytial virus, human metapneumovirus, rhinovirus, coronaviruses, parainfluenza viruses and adenovirus.

One hundred and twenty-nine (77%) samples were positive as detected by at least one method. Sixty-nine (41%) samples were positive by cell culture (excluding human metapneumovirus and coronaviruses), 116 (69%) by RT-PCR, 127 (76%) by MLPA and 100 (60%) by DPO. The MLPA yielded results in one attempt for all samples included while 12 (7.2%) samples had to be repeated by the DPO assay due to inconclusive results. The MLPA assay performed well in combination with either electrophoresis system, while the performance of the DPO assay was influenced by the electrophoresis systems.

Both molecular assays are comparable with real-time RT-PCR, more sensitive than viral culture and can detect dual infections easily. Results can be obtained within 1 day.

Bronchiolitis: recent evidence on diagnosis and management

Viral bronchiolitis is a leading cause of acute illness and hospitalization of young children. Research into the variation in treatment and outcomes for bronchiolitis across different settings has led to evidence-based clinical practice guidelines. Ongoing investigation continues to expand this body of evidence. Authors of recent surveillance studies have defined the presence of coinfections with multiple viruses in some cases of bronchiolitis. Underlying comorbidities and young age remain the most important predictors for severe bronchiolitis. Pulse oximetry plays an important role in driving use of health care resources. Evidence-based reviews have suggested a limited role for diagnostic laboratory or radiographic tests in typical cases of bronchiolitis. Several large, recent trials have revealed a lack of efficacy for routine use of either bronchodilators or corticosteroids for treatment of bronchiolitis. Preliminary evidence suggests a potential future role for a combination of these therapies and other novel treatments such as nebulized hypertonic saline.

Human metapneumovirus infections--biannual epidemics and clinical findings in children in the region of Basel, Switzerland

Human metapneumovirus (hMPV) epidemics vary in time and severity. We report findings for PCR for hMPV and respiratory syncytial virus (RSV) performed on nasopharyngeal aspirates (NPA) of hospitalized and outpatient children with respiratory tract infections between October 2004 and April 2008. A total of 3,934 NPAs were tested for hMPV and 3,859 for RSV. Of these, 198 (5%) were hMPV positive and 869 (23%) were RSV-positive. Median age was 17 months and 9 months for hMPV and RSV, respectively. Fifty-nine percent of hMPV and 58% of RSV patients were hospitalized. Proportions of hMPV positive samples for the four winter seasons were 0.4%, 11%, 0.2%, and 14%. For RSV, they were 28%, 15%, 28%, and 28%. HMPV epidemics follow a biannual variation in our area. Major epidemics were observed in winter seasons starting in odd years (2005/06 and 2007/08), minor epidemics in those starting in even years (2004/05 and 2006/07). RSV epidemics usually follow a reciprocal biannual pattern, leading to annually alternating major RSV and hMPV epidemics.