Viral load and acute otitis media development after human metapneumovirus upper respiratory tract infection

Human bocavirus and human metapneumovirus in hospitalized children with lower respiratory tract illness in Changsha, China

BACKGROUND

Lower respiratory tract illness is a major cause of morbidity and mortality in children worldwide, however, information about the epidemiological and clinical characteristics of LRTIs caused by HMPV and HBoV in China is limited.

OBJECTIVES

Human bocavirus (HBoV) and human metapneumovirus (HMPV) are two important viruses for children with lower respiratory tract infections (LRTI). We aimed to assay the correlation between viral load and clinical characteristics of HBoV and HMPV with LRTI in Changsha, China.

METHODS

Nasopharyngeal aspirates (NPAs) from children with LRTI were collected. Real-time PCR was used to screen HBoV and HMPV. Analyses were performed using SPSS 16.0 software.

RESULTS

Pneumonia was the most frequent diagnosis. There was no significant difference between HBoV- and HMPV-positive patients in age (P = .506) or hospitalization duration (P = .280); 24.1% and 18.2% were positive for HBoV and HMPV. HBoV infections peaked in summer (32.2%), and HMPV infections peaked in winter (28.9%). The HBoV-positive patients had a shorter hospitalization duration than the HBoV-negative patients (P = .021), and the HMPV-positive patients had a higher prevalence of fever than the HMPV-negative patients (P = .002). The HBoV viral load was significantly higher among patients aged <1 year (P = .006). The mean HBoV and HMPV viral loads were not significantly different between patients with single infections and coinfections. Patients infected with HBoV only were older than those coinfected with HBoV and other respiratory viruses (P = .005). No significant difference was found in the clinical characteristics of patients infected with HMPV only and those coinfected with HMPV and other respiratory viruses.

CONCLUSION

Pneumonia was the most frequent diagnosis caused by HBoV and HMPV. Neither HBoV nor HMPV viral load was correlated with disease severity.

Panel 4: Report of the Microbiology Panel

Objective To perform a comprehensive review of the literature from July 2011 until June 2015 on the virology and bacteriology of otitis media in children. Data Sources PubMed database of the National Library of Medicine. Review Methods Two subpanels comprising experts in the virology and bacteriology of otitis media were created. Each panel reviewed the relevant literature in the fields of virology and bacteriology and generated draft reviews. These initial reviews were distributed to all panel members prior to meeting together at the Post-symposium Research Conference of the 18th International Symposium on Recent Advances in Otitis Media, National Harbor, Maryland, in June 2015. A final draft was created, circulated, and approved by all panel members. Conclusions Excellent progress has been made in the past 4 years in advancing our understanding of the microbiology of otitis media. Numerous advances were made in basic laboratory studies, in animal models of otitis media, in better understanding the epidemiology of disease, and in clinical practice. Implications for Practice (1) Many viruses cause acute otitis media without bacterial coinfection, and such cases do not require antibiotic treatment. (2) When respiratory syncytial virus, metapneumovirus, and influenza virus peak in the community, practitioners can expect to see an increase in clinical otitis media cases. (3) Biomarkers that predict which children with upper respiratory tract infections will develop otitis media may be available in the future. (4) Compounds that target newly identified bacterial virulence determinants may be available as future treatment options for children with otitis media.

Clinical Features, Virus Identification, and Sinusitis as a Complication of Upper Respiratory Tract Illness in Children Ages 4-7 Years

OBJECTIVE

To determine the rate of sinusitis complicating upper respiratory tract illnesses (URIs) in children. We prospectively identified the clinical, virologic, and epidemiologic characteristics of URIs in a population of 4- to 7-year-old children followed for 1 year.

STUDY DESIGN

This was an observational cohort study in 2 primary care pediatric practices in Madison, Wisconsin. Nasal samples were obtained during 4 asymptomatic surveillance visits and during symptomatic URIs. A polymerase chain reaction-based assay for 9 respiratory viruses was performed on nasal samples. A diagnosis of sinusitis was based on published criteria.

RESULTS

Two hundred thirty-six children ages 48-96 months were enrolled. A total of 327 URIs were characterized. The mean number of URIs per child was 1.3 (range 0-9) per year. Viruses were detected in 81% of URIs; rhinovirus (RV) was most common. Seventy-two percent of URIs were resolved clinically by the 10th day. RV-A and RV-C were detected more frequently at URI visits; RV-B was detected at the same rate for both asymptomatic surveillance visits and URI visits. Sinusitis was diagnosed in 8.8% of symptomatic URIs. Viruses were detected frequently (33%) in samples from asymptomatic children.

CONCLUSIONS

Sinusitis occurred in 8.8% of symptomatic URIs in our study. The virus most frequently detected with URIs in children was RV; RV-A and RV-C detection but not RV-B detection were associated with illness. Viruses, especially RV, are detected frequently in asymptomatic children. Most URIs have improved or resolved by the 10th day after onset. Children experienced a mean of 1.3 URIs per year, which was lower than expected.

Importance of viruses in acute otitis media

PURPOSE OF REVIEW

Acute otitis media occurs as a complication of viral upper respiratory tract infection. Bacterial otopathogens and respiratory viruses interact and play important roles in acute otitis media development. A better understanding of viral and bacterial interactions may lead to innovative ways to lessen the burden of this common childhood disease.

RECENT FINDINGS

There has been increasing evidence that acute otitis media occurs during upper respiratory infection, even in the absence of nasopharyngeal bacterial colonization. Among the types of viruses associated with acute otitis media, respiratory syncytial virus continues to be the most commonly detected. It is still unclear whether viral load plays an important role in acute otitis media development, but symptomatic upper respiratory tract infection (as opposed to asymptomatic viral infection) is crucial. Widespread use of bacterial and viral vaccines in young children, including pneumococcal conjugate and influenza vaccines, has led to the reduction in otitis media-related healthcare use between 2001 and 2011. There has been no new vaccine against respiratory viruses other than influenza.

SUMMARY

Progress has been made toward the reduction of the burden of acute otitis media in the last decade. Success in reducing acute otitis media incidence will rely mainly on prevention of nasopharyngeal otopathogen colonization, as well as reduction in the incidence of viral upper respiratory tract infection.

Symptomatic and asymptomatic respiratory viral infections in the first year of life: association with acute otitis media development

Sensitive viral diagnostic methods have identified increasing prevalence of asymptomatic viral infection. This study determined the epidemiologic characteristics and etiology of asymptomatic upper respiratory tract infection in the first year of life and the association with acute otitis media complication.

Background. Sensitive diagnostic assays have increased the detection of viruses in asymptomatic individuals. The clinical significance of asymptomatic respiratory viral infection in infants is unknown.

Methods. High-throughput, quantitative polymerase chain reaction assays were used to detect 13 common respiratory viruses from nasopharyngeal specimens collected during 2028 visits from 362 infants followed from near birth up to 12 months of age. Specimens were collected at monthly interval (months 1–6 and month 9) and during upper respiratory tract infection (URTI) episodes. Subjects were followed closely for acute otitis media (AOM) development.

Results. Viruses were detected in 76% of 394 URTI specimens and 27% of asymptomatic monthly specimens. Rhinovirus was detected most often; multiple viruses were detected in 29% of the specimens. Generalized mixed-model analyses associated symptoms with increasing age and female sex; detection of respiratory syncytial virus (RSV), influenza, rhinovirus, metapneumovirus, and adenovirus was highly associated with symptoms. Increasing age was also associated with multiple virus detection. Overall, 403 asymptomatic viral infections in 237 infants were identified. Viral load was significantly higher in URTI specimens than asymptomatic specimens but did not differentiate cases of URTI with and without AOM complication. The rate of AOM complicating URTI was 27%; no AOM occurred following asymptomatic viral infections. AOM development was associated with increasing age and infection with RSV, rhinovirus, enterovirus, adenovirus, and bocavirus.

Conclusions. Compared to symptomatic infection, asymptomatic viral infection in infants is associated with young age, male sex, low viral load, specific viruses, and single virus detection. Asymptomatic viral infection did not result in AOM.

Acute bacterial sinusitis complicating viral upper respiratory tract infection in young children

BACKGROUND

Acute bacterial sinusitis (ABS) is a common complication of viral upper respiratory tract infections (URI). Clinical characteristics of URIs complicated by ABS in young children have not been well studied.

METHODS

We identified ABS episodes in a prospective, longitudinal cohort study of 294 children (6-35 months of age at enrollment), who were followed up for 1 year to capture all URI episodes and complications. At the initial URI visit seen by the study personnel (median day = 4 from symptoms onset), nasopharyngeal samples were obtained for bacterial cultures and viral studies.

RESULTS

Of 1295 documented URI episodes, 103 (8%) episodes (in 73 children) were complicated by ABS, 32 of which were concurrent with acute otitis media. The majority (72%) of ABS episodes were diagnosed based on persistent symptoms or a biphasic course. Average age at ABS diagnosis was 18.8 ± 7.2 months; White children were more likely to have ABS episodes than Blacks (P = 0.01). Hispanic/Latino ethnicity (P < 0.0001) was negatively associated, and adequate 7-valent pneumococcal conjugate vaccine immunization status (P = 0.001) appeared to increase the risk of ABS. Girls had more ABS episodes than boys (0.5 ± 0.8 vs. 0.3 ± 0.6 episodes/yr, respectively, P = 0.03). Viruses were detected in 63% during the initial URI visit; rhinovirus detection was positively correlated with ABS risk (P = 0.01). Bacterial cultures were positive in 82/83 (99%) available samples obtained at the initial URI visit; polymicrobial (56%), Moraxella catarrhalis (20%) and Streptococcus pneumoniae (10%) were the most common cultures. Presence of pathogenic bacteria overall and presence of M. catarrhalis during URI were positively correlated with the risk for ABS (P = 0.04 for both).

CONCLUSIONS

ABS complicates 8% of URI in young children. Girls have more frequent ABS episodes than boys. Presence of rhinovirus and M. catarrhalis during URI are positively correlated with the risk for ABS complication.

Role of Human Bocavirus in Upper Respiratory Tract Infections and Acute Otitis Media

BACKGROUND

Human bocavirus (HBoV) is a newly described parvovirus. HBoV1 has been associated with respiratory infections, including acute otitis media (AOM), but the knowledge on the significance of HBoV1 in upper respiratory tract infections (URI) and AOM in relation to other respiratory viruses is limited. The objective of this study was to compare the rate of detection of HBoV1 to that of other respiratory viruses in specimens from children with URI, with and without AOM complication.

METHODS

Nasopharyngeal secretions (NPS) were collected during URI from healthy children (6-35 months) followed prospectively for 1 year; specimens have been previously analyzed for broad spectrum of respiratory viruses. Archived NPS were analyzed for HBoV1 using a high-throughput, quantitative polymerase chain reaction method.

RESULTS

Seven hundred and seven NPS samples collected during URI episodes from 201 children were studied for HBoV1. A total of 94 (47%) children tested positive for HBoV1 DNA during 172 (24%) URI episodes; HBoV1 was present as the only virus in 44 (6%) URI episodes. Overall, 37% of URI episodes were complicated by AOM. Of URI associated with single virus (n = 303), the rate of AOM complicating URI associated with HBoV1 only was 52% (23 of 44); this was a higher AOM rate, compared to that of other respiratory viruses.

CONCLUSIONS

Among URI associated with single respiratory virus, HBoV1-URI was commonly associated with AOM complication. The important role of HBoV1 on AOM pathogenesis needs to be studied further.

Human metapneumovirus viral load is an important risk factor for disease severity in young children

BACKGROUND

The role of viral load in human metapneumovirus (HMPV) disease severity has not yet been clearly determined.

OBJECTIVE

We evaluated the importance of viral load along with other factors in HMPV disease severity among children aged <3 years old.

STUDY DESIGN

HMPV-positive cases were selected from a cohort of outpatients and hospitalized children with lower respiratory tract infections. HMPV groups (A or B) and viral loads were determined in their nasopharyngeal aspirates. Disease severity was defined by assessing risk for hospitalization and by using two validated clinical severity scores.

RESULTS

Of the 118 HMPV cases detected over 4 years for which viral load could be determined, 60 belonged to genotype A and 58 to genotype B. Baseline characteristics were similar in HMPV-A and HMPV-B mono-infected patients. In multivariate analysis, HMPV hospitalization was associated with viral load ≥1000 copies/10(4)cells (OR, 3.2; 95%CI, 1.4-7.4), age <6 months (OR, 3.1; 95%CI, 1.2-8.6) and presence of ≥3 children in the household (OR, 2.7; 95%CI, 1.04-6.9). A high HMPV viral load was also associated with pulmonary rales (p=.03), use of bronchodilators (p=.02) and inhaled corticosteroids (p=.01).

CONCLUSION

HMPV viral load is associated with disease severity in young children along with young age and household crowding.

Seasonality of acute otitis media and the role of respiratory viral activity in children

BACKGROUND

Acute otitis media (AOM) occurs as a complication of viral upper respiratory tract infections in young children. AOM and respiratory viruses both display seasonal variation. Our objective was to examine the temporal association between circulating respiratory viruses and the occurrence of pediatric ambulatory care visits for AOM.

METHODS

This retrospective study included 9 seasons of respiratory viral activity (2002 to 2010) in Utah. We used Intermountain Healthcare electronic medical records to assess community respiratory viral activity via laboratory-based active surveillance and to identify children <18 years with outpatient visits and International Classification of Diseases, Ninth Revision codes for AOM. We assessed the strength of the association between AOM and individual respiratory viruses using interrupted time series analyses.

RESULTS

During the study period, 96,418 respiratory viral tests were performed; 46,460 (48%) were positive. The most commonly identified viruses were respiratory syncytial virus (22%), rhinovirus (8%), influenza (8%), parainfluenza (4%), human metapneumovirus (3%) and adenovirus (3%). AOM was diagnosed during 271,268 ambulatory visits. There were significant associations between peak activity of respiratory syncytial virus, human metapneumovirus, influenza A and office visits for AOM. Adenovirus, parainfluenza and rhinovirus were not associated with visits for AOM.

CONCLUSIONS

Seasonal respiratory syncytial virus, human metapneumovirus and influenza activity were temporally associated with increased diagnoses of AOM among children. These findings support the role of individual respiratory viruses in the development AOM. These data also underscore the potential for respiratory viral vaccines to reduce the burden of AOM.

Viral-bacterial interactions in acute otitis media

Acute otitis media (AOM) is a polymicrobial disease, which usually occurs as a complication of viral upper respiratory tract infection (URI). While respiratory viruses alone may cause viral AOM, they increase the risk of bacterial middle ear infection and worsen clinical outcomes of bacterial AOM. URI viruses alter Eustachian tube (ET) function via decreased mucociliary action, altered mucus secretion and increased expression of inflammatory mediators among other mechanisms. Transient reduction in protective functions of the ET allows colonizing bacteria of the nasopharynx to ascend into the middle ear and cause AOM. Advances in research help us to better understand the host responses to viral URI, the mechanisms of viral-bacterial interactions in the nasopharynx and the development of AOM. In this review, we present current knowledge regarding viral-bacterial interactions in the pathogenesis and clinical course of AOM. We focus on the common respiratory viruses and their established role in AOM.