Impact of human metapneumovirus in childhood: comparison with respiratory syncytial virus and influenza viruses

The Burden of Human Metapneumovirus- and Influenza-Associated Hospitalizations in Adults in New Zealand, 2012-2015

BACKGROUND

Unlike influenza, information on the burden of human metapneumovirus (HMPV) as a cause of hospitalizations in adults with acute respiratory illness (ARI) is limited.

METHODS

We compared the population-based incidence, seasonality, and clinical characteristics of these 2 viral infections among adults aged ≥20 years with ARI hospitalizations in Auckland, New Zealand, during 2012-2015 through the Southern Hemisphere Influenza Vaccine Effectiveness Research and Surveillance (SHIVERS) project.

RESULTS

Of the 14 139 ARI hospitalizations, 276 of 6484 (4.3%) tested positive for HMPV and 1342 of 7027 (19.1%) tested positive for influenza. Crude rates of 9.8 (95% confidence interval [CI], 8.7-11.0) HMPV-associated and 47.6 (95% CI, 45.1-50.1) influenza-associated ARI hospitalizations were estimated for every 100 000 adult residents annually. The highest rates for both viruses were in those aged ≥80 years, of Māori or Pacific ethnicity, or living in low socioeconomic status (SES) areas. HMPV infections were more common than influenza in those with chronic medical conditions.

CONCLUSIONS

Although HMPV infections accounted for fewer hospitalizations than influenza in adults aged ≥20 years, HMPV-associated ARI hospitalization rates were higher than influenza in older adults, Māori and Pacific people, and those of low SES. This highlights a need for vaccine/antiviral development.

Safety and Efficacy of Nirsevimab in a Universal Prevention Program of Respiratory Syncytial Virus Bronchiolitis in Newborns and Infants in the First Year of Life in the Valle d'Aosta Region, Italy, in the 2023-2024 Epidemic Season

Respiratory syncytial virus (RSV) bronchiolitis remains a significant global health burden, particularly in newborns and infants during their first year of life. The quest for an effective preventive strategy against RSV has long been sought, and recent developments have shown promise in the form of nirsevimab, a monoclonal antibody specifically designed for RSV prophylaxis. Valle d'Aosta was the first Italian region to propose universal prophylaxis with nirsevimab for newborns and infants in their first epidemic season as early as 2023-2024. This study describes the effectiveness and safety of the universal prevention program of RSV bronchiolitis using the monoclonal antibody nirsevimab in children resident in Valle d'Aosta born during the 2023-2024 epidemic season. There were 556 neonates born from 1 May 2023 to 15 February 2024. The risk of hospitalization for RSV bronchiolitis in 2023-2024 was 3.2%, compared to 7% in the 2022-2023 epidemic season (p < 0.001). After the start of the prophylaxis campaign with nirsevimab, the risk of hospitalization was 8.3% in the sample of infants who did not adhere to the prophylaxis, while no child in the sample of those treated (p < 0.001) was hospitalized for bronchiolitis. Few mild transient side effects were reported. This study shows the efficacy and safety of universal prophylaxis with nirsevimab in neonates, making Valle d'Aosta the first Italian region to offer universal prophylaxis to newborns without risk factors for RSV complications. Future research could further explore its long-term impact and cost-effectiveness.

Biomarkers for Serious Bacterial Infections in Febrile Children

Febrile infections in children are a common cause of presentation to the emergency department (ED). While viral infections are usually self-limiting, sometimes bacterial illnesses may lead to sepsis and severe complications. Inflammatory biomarkers such as C reactive protein (CRP) and procalcitonin are usually the first blood exams performed in the ED to differentiate bacterial and viral infections; nowadays, a better understanding of immunochemical pathways has led to the discovery of new and more specific biomarkers that could play a role in the emergency setting. The aim of this narrative review is to provide the most recent evidence on biomarkers and predictor models, combining them for serious bacterial infection (SBI) diagnosis in febrile children. Literature analysis shows that inflammatory response is a complex mechanism in which many biochemical and immunological factors contribute to the host response in SBI. CRP and procalcitonin still represent the most used biomarkers in the pediatric ED for the diagnosis of SBI. Their sensibility and sensitivity increase when combined, and for this reason, it is reasonable to take them both into consideration in the evaluation of febrile children. The potential of machine learning tools, which represent a real novelty in medical practice, in conjunction with routine clinical and biological information, may improve the accuracy of diagnosis and target therapeutic options in SBI. However, studies on this matter are not yet validated in younger populations, making their relevance in pediatric precision medicine still uncertain. More data from further research are needed to improve clinical practice and decision making using these new technologies.

Epidemiology and Burden of Influenza in Children 0-14 Years Over Ten Consecutive Seasons in Italy

BACKGROUND

In Europe, influenza vaccination coverage in the pediatric population is low. This study describes the influenza incidence and associated healthcare utilization in the pediatric population in Italy.

METHODS

Deidentified data from electronic medical records for children 0-14 years old seen by >150 family pediatricians in the Pedianet network in Italy were evaluated for 10 influenza seasons spanning 2010-2020. Incidence of influenza (cases per 1000 person-months), related sequelae and associated healthcare resource use were determined using diagnostic, prescription and medical examination data.

RESULTS

Over 10 seasons, an average of 8892 influenza cases (range, 4700-12,419; total 88,921) were diagnosed in a cohort of 1,432,384 children 0-14 years of age. Influenza vaccination coverage was 3.6% among children with an influenza diagnosis and 6.8% among children without. Influenza-related healthcare resource utilization included 1.58 family pediatrician visits per influenza episode and 220 ED and 111 hospital admissions, with the highest resource usage among children 1-4 years and lowest among children <6 months old. The most common influenza complications were acute otitis media (2.9% of influenza cases) and pneumonia (0.5%). Antibiotics were prescribed in 38.7% of influenza cases; no antiviral agents were prescribed. One intensive care unit admission and 2 cases requiring ventilatory support were documented. No influenza-related deaths were reported.

CONCLUSION

Pediatric influenza vaccination was low despite the burden and healthcare use related to seasonal influenza in the pediatric population during a 10-year period in Italy.

The burden of seasonal influenza in Italy: A systematic review of influenza-related complications, hospitalizations, and mortality

Reliable country‐specific data on influenza burden play a crucial role in informing prevention and control measures. Our purpose was to provide a comprehensive summary of the available evidence on the burden of seasonal influenza in Italy. We performed a systematic literature review of articles published until July 31, 2020. PubMed, Embase, and Web of Science were searched using terms related to burden, influenza, and Italian population. We included studies investigating seasonal influenza‐related complications, hospitalizations, and/or mortality. Sixteen studies were included: eight (50%) analyzed influenza‐related complications, eight (50%) hospitalizations, and seven (43.8%) influenza‐related deaths. Only three studies (19.7%) concerned pediatric age. The synthesis of results showed that patients with chronic conditions have an increased risk for complications up to almost three times as compared with healthy people. Hospitalizations due to influenza can occur in as much as 5% of infected people depending on the study setting. Excess deaths rates were over sixfold higher in the elderly as compared with the rest of population. Although there are still gaps in existing data, there is evidence of the significant burden that influenza places each year especially on high‐risk groups. These data should be used to inform public health decision‐making.

Visual detection of human metapneumovirus using CRISPR-Cas12a diagnostics

Human metapneumovirus (HmPV) is a common and serious virus that causes respiratory tract infection. This study aimed to develop a detection technique by combining reverse transcription recombinase polymerase amplification (RT-RPA) with CRISPR-Cas12a (RT-RPA-Cas12a) for clinical diagnosis of HmPV. Herein, four primer pairs targeting partial nucleoprotein (N) gene of HmPV were designed and evaluated. Then, the products amplified by RT-RPA were detected using CRISPR-Cas12a combined with fluorescence or lateral flow (LF). RT-RPA-Cas12a-based fluorescence or LF assay can be completed within 35 min or 45 min, and the detection limit was up to 6.97 × 10² copies/mL. And there was no cross reaction with human bocavirus, respiratory syncytial virus, adenovirus and parainfluenza virus. By combining with LF, the detection results were evaluated by naked eyes. Furthermore, 28 clinical samples were applied to examine the performance of RT-RPA-Cas12a system. The detection coincidence rates of RT-RPA-Cas12a-fluorescence and RT-RPA-Cas12a-LF with quantitative RT-PCR were 96.4% and 92.9%, respectively. Together, the new method for detecting HmPV with high sensitivity and specificity based on RT-RPA-Cas12a-fluorescence or LF shows promising potential for clinical diagnosis of HmPV without professional skills or ancillary equipment.

Cell-Mediated Responses to Human Metapneumovirus Infection

Viruses are the most common cause of acute respiratory tract infections (ARTI). Human metapneumovirus (hMPV) frequently causes viral pneumonia which can become life-threatening if the virus spreads to the lungs. Even though hMPV was only isolated in 2001, this negative-stranded RNA virus has probably been circulating in the human population for many decades. Interestingly, almost all adults have serologic evidence of hMPV infection. A well-established host immune response is evoked when hMPV infection occurs. However, the virus has evolved to circumvent and even exploit the host immune response. Further, infection with hMPV induces a weak memory response, and re-infections during life are common. In this review, we provide a comprehensive overview of the different cell types involved in the immune response in order to better understand the immunopathology induced by hMPV. Such knowledge may contribute to the development of vaccines and therapeutics directed against hMPV.

Cell-Mediated Responses to Human Metapneumovirus Infection

Viruses are the most common cause of acute respiratory tract infections (ARTI). Human metapneumovirus (hMPV) frequently causes viral pneumonia which can become life-threatening if the virus spreads to the lungs. Even though hMPV was only isolated in 2001, this negative-stranded RNA virus has probably been circulating in the human population for many decades. Interestingly, almost all adults have serologic evidence of hMPV infection. A well-established host immune response is evoked when hMPV infection occurs. However, the virus has evolved to circumvent and even exploit the host immune response. Further, infection with hMPV induces a weak memory response, and re-infections during life are common. In this review, we provide a comprehensive overview of the different cell types involved in the immune response in order to better understand the immunopathology induced by hMPV. Such knowledge may contribute to the development of vaccines and therapeutics directed against hMPV.

Cell-Mediated Responses to Human Metapneumovirus Infection

Viruses are the most common cause of acute respiratory tract infections (ARTI). Human metapneumovirus (hMPV) frequently causes viral pneumonia which can become life-threatening if the virus spreads to the lungs. Even though hMPV was only isolated in 2001, this negative-stranded RNA virus has probably been circulating in the human population for many decades. Interestingly, almost all adults have serologic evidence of hMPV infection. A well-established host immune response is evoked when hMPV infection occurs. However, the virus has evolved to circumvent and even exploit the host immune response. Further, infection with hMPV induces a weak memory response, and re-infections during life are common. In this review, we provide a comprehensive overview of the different cell types involved in the immune response in order to better understand the immunopathology induced by hMPV. Such knowledge may contribute to the development of vaccines and therapeutics directed against hMPV.

INFECTIONS IN PREGNANCY WITH COVID-19 AND OTHER RESPIRATORY RNA VIRUS DISEASES ARE RARELY, IF EVER, TRANSMITTED TO THE FETUS: EXPERIENCES WITH CORONAVIRUSES, HPIV, hMPV RSV, AND INFLUENZA

SARS-CoV-2, the agent of COVID-19, is similar to two other coronaviruses, SARS-CoV and MERS-CoV, in causing life-threatening maternal respiratory infections and systemic complications. Because of global concern for potential intrauterine transmission of SARS-CoV-2 from pregnant women to their infants, this report analyzes the effects on pregnancy of infections caused by SARS-CoV-2 and other respiratory RNA viruses, and examines the frequency of maternal-fetal transmission with SARS-CoV-2, severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), influenza, respiratory syncytial virus (RSV), parainfluenza (HPIV) and metapneumovirus (hMPV). There have been no confirmed cases of intrauterine transmission reported with COVID-19 or any other coronavirus infections. Influenza virus, despite causing approximately one billion annual infections globally, has only a few cases of confirmed or suspected intrauterine fetal infections reported. RSV is in an unusual cause of illness among pregnant women, and with the exception of one premature infant with congenital pneumonia, no other cases of maternal-fetal infection are described. Parainfluenza virus and human metapneumovirus can produce symptomatic maternal infections but do not cause intrauterine fetal infection. In summary, it appears that the absence thus far of maternal-fetal transmission of the SARS-CoV-2 virus during the COVID-19 pandemic is similar to other coronaviruses, and is also consistent with the extreme rarity of suggested or confirmed cases of intrauterine transmission of other respiratory RNA viruses. This observation has important consequences for pregnant women as it appears that if intrauterine transmission of SARSCoV-2 does eventually occur, it will be a rare event. Potential mechanisms of fetal protection from maternal viral infections are also discussed.

Engineering of Live Chimeric Vaccines against Human Metapneumovirus

Human metapneumovirus (HMPV) is an important human pathogen that, along with respiratory syncytial virus (RSV), is a major cause of respiratory tract infections in young infants. Development of an effective vaccine against Pneumoviruses has proven to be particularly difficult; despite over 50 years of research in this field, no vaccine against HMPV or RSV is currently available. Recombinant chimeric viruses expressing antigens of other viruses can be generated by reverse genetics and used for simultaneous immunization against more than one pathogen. This approach can result in the development of promising vaccine candidates against HMPV, and several studies have indeed validated viral vectors expressing HMPV antigens. In this review, we summarize current efforts in generating recombinant chimeric vaccines against HMPV, and we discuss their potential optimization based on the correspondence with RSV studies.

Distinction between rhinovirus-induced acute asthma and asthma-augmented influenza infection

BACKGROUND

Rhinovirus (RV) is an established trigger of asthma attacks, whereas such a link is less consistent for influenza virus (IFV).

OBJECTIVE

In the context of precision medicine, we hypothesized that IFV infection may cause a condition essentially different from RV, and we investigated this by evaluating clinical characteristics of RV/IFV-positive and -negative children with respiratory symptoms and/or fever.

METHODS

One thousand two hundred and seven children, 6 months to 13 years old, hospitalized for flu-like illness were recruited in this cross-sectional study. Collected information included demographics, medical history, symptoms/physical findings/diagnosis at presentation and treatment. Nasal secretions were PCR-tested for IFV/RV. Associations were evaluated with adjusted logistic regression models.

RESULTS

Rhinovirus positivity was associated with an asthma-like presentation, including increased wheeze/effort of breathing/diagnosis of acute asthma, and decreased fever/vomiting. Conversely, IFV⁺ children presented with less wheeze/effort of breathing/diagnosis of acute asthma, while they were more frequently febrile. In those with previous asthma history, both viruses induced wheeze; however, IFV was uniquely associated with a more generalised and severe presentation including fever, rales, intercostal muscle retractions and lymphadenopathy. These symptoms were not seen in RV⁺ asthmatics, who had fewer systemic signs and more cough.

CONCLUSIONS AND CLINICAL RELEVANCE

In children with respiratory symptoms and/or fever, RV but not IFV is associated with wheeze and an asthma-like presentation. In those with an asthma history, IFV causes more generalised and severe disease that may be better described as "asthma-augmented influenza" rather than an "asthma attack." Differences in the acute conditions caused by these viruses should be considered in the design of epidemiological studies.

Human metapneumovirus in hospitalized children less than 5 years of age in Pakistan

Acute respiratory infection (ARI) is the second leading cause of death in children less than 5 years of age worldwide. Human Metapneumovirus (hMPV) is associated with around 5-7% of the total pneumonia admissions in children. The aim of this study was to determine the magnitude of hMPV associated hospitalizations among children, in Karachi, Pakistan. A 3 years prospective study was conducted at the Aga Khan University Hospital (AKUH), from August 2009 to June 2012. Children less than 5 years of age, admitted with ARIs, were enrolled. Throat swabs were collected and tested for hMPV using real-time PCR. Multivariable log binomial regression analysis was performed. Out of 1150 children enrolled, hMPV was detected among 84/1150 (7%). About 87% of the enrolled children presented with cough, followed by fever (73%), nasal congestion (69%) and shortness of breath (68%). Of the hMPV positive subjects, most (56/84, 67%) were less than 12 months of age. The most common diagnosis in hMPV positive infants was pneumonia, followed by asthma and bronchiolitis. HMPV was identified year round, with peaks during February and August. Sore throat was found to be significantly associated with the hMPV infection (Adjusted RR 2.23; 95%CI 1.42-3.52). The proportion of hMPV was higher among hospitalized infants with ARI. Pneumonia was the primary discharge diagnoses of patients who tested positive for hMPV. hMPV could be a target for future vaccine to further decrease the burden of ARI morbidity and possibly mortality in developing countries.

A comparison of RSV and influenza in vitro kinetic parameters reveals differences in infecting time

Influenza and respiratory syncytial virus (RSV) cause acute infections of the respiratory tract. Since the viruses both cause illnesses with similar symptoms, researchers often try to apply knowledge gleaned from study of one virus to the other virus. This can be an effective and efficient strategy for understanding viral dynamics or developing treatment strategies, but only if we have a full understanding of the similarities and differences between the two viruses. This study used mathematical modeling to quantitatively compare the viral kinetics of in vitro RSV and influenza virus infections. Specifically, we determined the viral kinetics parameters for RSV A2 and three strains of influenza virus, A/WSN/33 (H1N1), A/Puerto Rico/8/1934 (H1N1), and pandemic H1N1 influenza virus. We found that RSV viral titer increases at a slower rate and reaches its peak value later than influenza virus. Our analysis indicated that the slower increase of RSV viral titer is caused by slower spreading of the virus from one cell to another. These results provide estimates of dynamical differences between influenza virus and RSV and help provide insight into the virus-host interactions that cause observed differences in the time courses of the two illnesses in patients.

Human metapneumovirus - what we know now

Human metapneumovirus (HMPV) is a leading cause of acute respiratory infection, particularly in children, immunocompromised patients, and the elderly. HMPV, which is closely related to avian metapneumovirus subtype C, has circulated for at least 65 years, and nearly every child will be infected with HMPV by the age of 5. However, immunity is incomplete, and re-infections occur throughout adult life. Symptoms are similar to those of other respiratory viral infections, ranging from mild (cough, rhinorrhea, and fever) to more severe (bronchiolitis and pneumonia). The preferred method for diagnosis is reverse transcription-polymerase chain reaction as HMPV is difficult to culture. Although there have been many advances made in the past 16 years since its discovery, there are still no US Food and Drug Administration-approved antivirals or vaccines available to treat HMPV. Both small animal and non-human primate models have been established for the study of HMPV. This review will focus on the epidemiology, transmission, and clinical manifestations in humans as well as the animal models of HMPV pathogenesis and host immune response.

School absenteeism among school-aged children with medically attended acute viral respiratory illness during three influenza seasons, 2012-2013 through 2014-2015

BACKGROUND

Acute respiratory illnesses (ARIs) are common in school-aged children, but few studies have assessed school absenteeism due to specific respiratory viruses.

OBJECTIVE

To evaluate school absenteeism among children with medically attended ARI due to common viruses.

METHODS

We analyzed follow-up surveys from children seeking care for acute respiratory illness who were enrolled in the influenza vaccine effectiveness study at Marshfield Clinic during the 2012-2013 through 2014-2015 influenza seasons. Archived influenza-negative respiratory swabs were retested using multiplex RT-PCR to detect 16 respiratory virus targets. Negative binomial and logistic regression models were used to examine the association between school absence and type of respiratory viruses; endpoints included mean days absent from school and prolonged (>2 days) absence. We examined the association between influenza vaccination and school absence among children with RT-PCR-confirmed influenza.

RESULTS

Among 1027 children, 2295 days of school were missed due to medically attended ARIs; influenza accounted for 39% of illness episodes and 47% of days missed. Mean days absent were highest for influenza (0.96-1.19) and lowest for coronavirus (0.62). Children with B/Yamagata infection were more likely to report prolonged absence than children with A/H1N1 or A/H3N2 infection [OR (95% CI): 2.1 (1.0, 4.5) and 1.7 (1.0, 2.9), respectively]. Among children with influenza, vaccination status was not associated with prolonged absence.

CONCLUSIONS

School absenteeism due to medically attended ARIs varies by viral infection. Influenza B infections accounted for the greatest burden of absenteeism.

Current developments and prospects on human metapneumovirus vaccines

INTRODUCTION

Human metapneumovirus (hMPV) has become one of the major pathogens causing acute respiratory infections (ARI) mainly affecting young children, immunocompromised patients, and the elderly. Currently there are no licensed vaccines against this virus. Areas covered: Since the discovery of hMPV in 2001, many groups have focused on developing vaccines against this pathogen. This review presents the outcomes and perspectives derived from preclinical studies performed in cell cultures and animals as well as the only candidate that has reached evaluation in a clinical trial. Limitations of the current vaccine candidates are discussed and perspectives for the development of plant-based vaccines are analyzed. Expert commentary: Several hMPV vaccine candidates are under development with the potential to progress into clinical trials. In parallel, the molecular farming field offers new opportunities to generate innovative vaccines that will offer several advantages in the fight against hMPV.

Metapneumovirus Infections and Respiratory Complications

Acute respiratory tract infections (ARTIs) are the most common illnesses experienced by people of all ages worldwide. In 2001, a new respiratory pathogen called human metapneumovirus (hMPV) was identified in respiratory secretions. hMPV is an RNA virus of the Paramyxoviridae family, and it has been isolated on every continent and from individuals of all ages. hMPV causes 7 to 19% of all cases of ARTIs in both hospitalized and outpatient children, and the rate of detection in adults is approximately 3%. Symptoms of hMPV infection range from a mild cold to a severe disease requiring a ventilator and cardiovascular support. The main risk factors for severe disease upon hMPV infection are the presence of a high viral load, coinfection with other agents (especially human respiratory syncytial virus), being between 0 and 5 months old or older than 65 years, and immunodeficiency. Currently, available treatments for hMPV infections are only supportive, and antiviral drugs are employed in cases of severe disease as a last resort. Ribavirin and immunoglobulins have been used in some patients, but the real efficacy of these treatments is unclear. At present, the direction of research on therapy for hMPV infection is toward the development of new approaches, and a variety of vaccination strategies are being explored and tested in animal models. However, further studies are required to define the best treatment and prevention strategies.

Human metapneumovirus in the preterm neonate: current perspectives

Premature birth (<37 weeks gestation) occurs in ~11% of all births in the US. These infants are at risk of chronic lung disease and respiratory conditions, including bronchopulmonary dysplasia. Respiratory viruses are important causes of acute respiratory illness (ARI) in preterm infants, leading to rehospitalization, increased health care burden, and long-term morbidity. Human metapneumovirus (HMPV) is a paramyxovirus discovered in 2001 that is related to respiratory syncytial virus. Epidemiologic studies show that HMPV is a leading cause of ARI in children and adults worldwide. Prematurity is a major risk factor for severe HMPV disease, requiring hospitalization. Moreover, limited data suggest that HMPV infection during infancy is associated with asthma and recurrent wheezing, which are common long-term pulmonary complication of prematurity. HMPV causes nosocomial outbreaks of ARI in hospitals and long-term care facilities, although there are few studies of the prevalence of HMPV in neonatal intensive care unit populations. HMPV is a common and important virus in premature infants, and caregivers for preterm infants should consider this virus in patients with acute respiratory symptoms.

Genome-Wide Analysis of Human Metapneumovirus Evolution

Human metapneumovirus (HMPV) has been described as an important etiologic agent of upper and lower respiratory tract infections, especially in young children and the elderly. Most of school-aged children might be introduced to HMPVs, and exacerbation with other viral or bacterial super-infection is common. However, our understanding of the molecular evolution of HMPVs remains limited. To address the comprehensive evolutionary dynamics of HMPVs, we report a genome-wide analysis of the eight genes (N, P, M, F, M2, SH, G, and L) using 103 complete genome sequences. Phylogenetic reconstruction revealed that the eight genes from one HMPV strain grouped into the same genetic group among the five distinct lineages (A1, A2a, A2b, B1, and B2). A few exceptions of phylogenetic incongruence might suggest past recombination events, and we detected possible recombination breakpoints in the F, SH, and G coding regions. The five genetic lineages of HMPVs shared quite remote common ancestors ranging more than 220 to 470 years of age with the most recent origins for the A2b sublineage. Purifying selection was common, but most protein genes except the F and M2-2 coding regions also appeared to experience episodic diversifying selection. Taken together, these suggest that the five lineages of HMPVs maintain their individual evolutionary dynamics and that recombination and selection forces might work on shaping the genetic diversity of HMPVs.

Detection of Human Metapneumovirus and Respiratory Syncytial Virus by Real-Time Polymerase Chain Reaction Among Hospitalized Young Children in Iran

Background

Acute respiratory infection plays an important role in hospitalization of children in developing countries; detection of viral causes in such infections is very important. The respiratory syncytial virus (RSV) is the most common etiological agent of viral lower respiratory tract infection in children, and human metapneumovirus (hMPV) is associated with both upper and lower respiratory tract infections among infants and children.

Objectives

This study evaluated the frequency and seasonal prevalence of hMPV and RSV in hospitalized children under the age of five, who were admitted to Aliasghar children’s hospital of Iran University of Medical Sciences from March 2010 until March 2013.

Patients and Methods

Nasopharyngeal or throat swabs from 158 hospitalized children with fever and respiratory distress were evaluated for RSV and hMPV RNA by the real-time polymerase chain reaction (PCR) method.

Results

Among the 158 children evaluated in this study, 49 individuals (31.1%) had RSV infection while nine individuals (5.7%) had hMPV infection. Five (55.5%) of the hMPV-infected children were male while four (44.5%) were female and 27 (55.2%) of the RSV-infected patients were females and 22 (44.8%) were males. The RSV infections were detected in mainly < one year old children and hMPV infections were detected mainly in > one year old children. Both RSV and hMPV infections had occurred mainly during winter and spring seasons.

Conclusions

Respiratory syncytial virus was the major cause of acute respiratory infection in children under one-year of age while human metapneumovirus had a low prevalence in this group. The seasonal occurrence of both viruses was the same.

Vitamin D and respiratory tract infections in childhood

BACKGROUND

Respiratory tract infections (RTIs) remain among of the most important causes of morbidity and mortality among children. Several studies have associated vitamin D deficiency with an increased risk of RTIs, and vitamin D supplementation has been proposed as a possible preventive measure against RTIs in children. The main aim of this review is to summarize the current evidence from the literature about the link between vitamin D and RTIs in children.

DISCUSSION

Several recent studies have shown that vitamin D has different immunomodulatory properties associated with the risk of RTIs in childhood. In this regard, it is very important to understand the definition of deficiency and insufficiency of vitamin D and when and how to treat this condition. Unfortunately, there is no consensus, although a level of at least 10 ng/mL 25-hydroxycholecalciferol (25[OH]D) is thought to be necessary to promote bone mineralization and calcium homeostasis, and a concentration between 20 ng/mL and 50 ng/mL is considered adequate to provide an immunomodulatory effect. Available data support a role for vitamin D deficiency in the risk of pediatric tuberculosis, recurrent acute otitis media, and severe bronchiolitis, whereas further studies are needed to confirm an association in children with recurrent pharyngotonsillitis, acute rhinosinusitis and community-acquired pneumonia.

CONCLUSIONS

Maintenance of adequate vitamin D status may be an effective and inexpensive prophylactic method against some RTIs, but the supplementation regimen has not been clearly defined. Further clinical trials are needed to determine the 25(OH)D concentrations associated with an increased risk of RTIs and optimal vitamin D supplementation regimen according to the type of RTI while also taking into consideration vitamin D receptor polymorphisms.

Respiratory Infections in the U.S. Military: Recent Experience and Control

This comprehensive review outlines the impact of military-relevant respiratory infections, with special attention to recruit training environments, influenza pandemics in 1918 to 1919 and 2009 to 2010, and peacetime operations and conflicts in the past 25 years. Outbreaks and epidemiologic investigations of viral and bacterial infections among high-risk groups are presented, including (i) experience by recruits at training centers, (ii) impact on advanced trainees in special settings, (iii) morbidity sustained by shipboard personnel at sea, and (iv) experience of deployed personnel. Utilizing a pathogen-by-pathogen approach, we examine (i) epidemiology, (ii) impact in terms of morbidity and operational readiness, (iii) clinical presentation and outbreak potential, (iv) diagnostic modalities, (v) treatment approaches, and (vi) vaccine and other control measures. We also outline military-specific initiatives in (i) surveillance, (ii) vaccine development and policy, (iii) novel influenza and coronavirus diagnostic test development and surveillance methods, (iv) influenza virus transmission and severity prediction modeling efforts, and (v) evaluation and implementation of nonvaccine, nonpharmacologic interventions.

[Viral epidemiology and clinical severity during the peak of the influenza A(H1N1) variant epidemic in febrile respiratory diseases of children]

En mars 2009, un nouveau virus a fait émergence, le virus Influenzae A(H1N1) variant. Nous avons voulu en étudier la répercussion médicale.

Objectifs

Définir la prévalence virale dans les atteintes respiratoires fébriles hospitalisées de l’enfant en période d’épidémie grippale A(H1N1) variant et déterminer les caractéristiques cliniques, paracliniques et évolutives liées aux virus identifiés.

Méthodes

Il s’est agi d’une étude épidémiologique, prospective, monocentrique menée à l’hôpital des Enfants du centre hospitalier universitaire de Bordeaux (Aquitaine, France) pendant l’épidémie grippale du 23 novembre au 20 décembre 2009 inclus. Tous les enfants hospitalisés pour atteinte respiratoire fébrile ont été inclus.

Résultats

Soixante-treize enfants ont été inclus. Une identification virale a été possible dans 52 % des cas, incluant 23 % de A(H1N1) variant [A(H1N1)v] et 29 % d’autres identifications dont 22 % de virus respiratoires syncitiaux. Une seule co-infection a été observée entre le virus [A(H1N1)v] et un pool viral (adénovirus ou virus para-influenzae ou bocavirus). Il n’existait pas de différence significative concernant l’âge, le sexe ou les facteurs de risque de gravité en fonction des virus identifiés. Concernant le virus [A(H1N1)v], les symptômes les plus fréquents étaient l’altération de l’état général, la toux, les atteintes oto-rhino-laryngologiques et les anomalies de la fréquence respiratoire, avec significativement moins de signes de lutte et d’anomalie auscultatoire mais plus de convulsions. Sur le plan paraclinique, il n’y avait pas de différence significative entre les groupes. Évolution et prise en charge ont été comparables.

Conclusion

Une faible prédominance du virus [A(H1N1)v] a été notée pendant l’épidémie grippale en Aquitaine dans les atteintes respiratoires fébriles justifiant une hospitalisation. Les caractéristiques cliniques, paracliniques et évolutives étaient peu spécifiques. L’ensemble de ces éléments n’a pas révélé de gravité particulière liée au virus [A(H1N1)v].

Viral aetiology and clinical outcomes in hospitalised infants presenting with respiratory distress

AIM

To determine the prevalence of various types of viruses in infants hospitalised due to respiratory distress, compare molecular diagnostic tests and evaluate symptom severity.

METHODS

All 136 nasopharyngeal aspirates from infants hospitalised for respiratory distress over a 9-month period were analysed for virus type by in-house respiratory syncytial virus (RSV) polymerase chain reaction (PCR) microarray-based and/or Luminex-based multiplex molecular tests. Medical records were reviewed retrospectively for clinical data.

RESULTS

Viral aetiology was confirmed in 126 subjects (92.6%) with 26 infected by more than one virus. RSVA/B was the most common (50.9%), followed by entero/rhinovirus (21.6%), human metapneumovirus (10.5%), parainfluenza virus (5.9%) and influenza (3.3%). RSV-infected infants had significantly lower saturation levels (89% versus 92%, p < 0.001), higher demand for oxygen (42.7% versus 21.6%, p = 0.021) and fluids (28% versus 9.8%; p = 0.014) and longer hospital stays (4 versus 3 days, <0.001) than other viruses. Luminex assays gave repeatable, slightly less sensitive results than in-house RSV PCR. Microarray-based assays were more sensitive, however, producing some unrepeatable results.

CONCLUSION

Respiratory syncytial virus dominates as the viral cause in hospitalised infants with respiratory distress in Sweden during the winter season, resulting in a clinical course that is significantly more severe. The multiplex assays produced reasonably concordant results.

Human metapneumovirus: insights from a ten-year molecular and epidemiological analysis in Germany

Human metapneumovirus (HMPV) is a cause of respiratory tract illness at all ages. In this study the epidemiological and molecular diversity among patients of different ages was investigated. Between 2000-2001 and 2009-2010, HMPV was detected in 3% (138/4,549) of samples from outpatients with influenza-like illness with a new, sensitive real-time RT-PCR assay. Several hundred (797) clinical specimens from hospitalized children below the age of 4 years with acute respiratory illness were investigated and HMPV was detected in 11.9% of them. Investigation of outpatients revealed that HMPV infections occurred in individuals of all ages but were most prevalent in children (0-4 years) and the elderly (>60 years). The most present clinical features of HMPV infections were cough, bronchitis, fever/shivers and pneumonia. About two thirds of HMPV-positive samples were detected in February and March throughout the study period. Molecular characterization of HMPV revealed a complex cyclic pattern of group dominance where HMPV subgroup A and B viruses predominated in general for three consecutive seasons. German HMPV represented all genetic lineages including A1, A2, B1, B2, sub-clusters A2a and A2b. For Germany, not only time-dependent circulation of lineages and sub-clusters was observed but also co-circulation of two or three predominant lineages. Two newly emerging amino acid substitutions (positions 223 and 280) of lineage B2 were detected in seven German HMPV sequences. Our study gives new insights into the molecular epidemiology of HMPV in in- and outpatients over a time period of 10 years for the first time. It is one of only few long-term surveillance studies in Europe, and allows comparative molecular analyses of HMPV circulating worldwide.

Spectrum of respiratory viruses circulating in eastern India: prospective surveillance among patients with influenza-like illness during 2010-2011

In developing countries, viruses causing respiratory disease are a major concern of public health. During January 2010-December 2011, 2,737 patients with acute respiratory infection from the outpatient departments as well as patients admitted to hospitals were screened for different respiratory viruses. Nasal and or throat swabs were collected and transported to the laboratory where initial screening of influenza A and influenza B viruses was performed. The samples were tested further for influenza C virus, parainfluenza viruses 1-4, human rhinovirus, metapneumovirus and respiratory syncytial virus by conventional RT- PCR. The study revealed that the majority of the patients were under 5 years of age; both due to their higher susceptibility to respiratory infections and presentation to hospitals. Out of 2,737 patients enrolled in this study, 59% were found positive for one or more respiratory viruses. Influenza B infection was detected in 12% of patients followed by influenza A (11.7%), respiratory syncytial virus (7.1%), parainfluenza virus-2 (6%), metapneumovirus (3%), parainfluenza virus-3 (1%), parainfluenza virus-4 (0.6%), parainfluenza virus-1 (0.3%), influenza C (0.2%) and human rhinovirus (0.2%). Distinct seasonal infection was observed only for influenza A and influenza B viruses.

The healthcare and societal burden associated with influenza in vaccinated and unvaccinated European and Israeli children

Few data exist regarding the healthcare and societal burden of culture-confirmed influenza illness in European and Israeli children. The current analysis describes this burden in vaccinated and unvaccinated children 2-17 years of age. Healthcare and societal burden outcomes were prospectively collected for culture-confirmed influenza illness in three previous randomized studies: a study of live attenuated influenza vaccine (LAIV) versus placebo in children aged <48 months attending day care (N = 846-973), and studies of LAIV versus inactivated influenza vaccine (IIV) in children aged <72 months with recurrent respiratory infections (N = 1,609) and in children aged 6-17 years with asthma (N = 2,211). The incidence of each endpoint among enrolled subjects and subjects with influenza was determined by treatment group and by country. Among subjects with influenza, 57-91% missed school or day care, 45-90% used non-antibiotic medications, 29-55% of parents missed work, 17-55% used antibiotics, 11-62% had additional provider visits, and 9-20% had acute otitis media. Where evaluated, rates of outcomes were generally similar between countries. Among all children enrolled, LAIV recipients missed 324-902 and 150 fewer days of day care per 1,000 children than those of placebo and IIV recipients, respectively; parents of LAIV recipients missed 197-340 and 76 fewer days of work per 1,000 children than those of placebo and IIV recipients, respectively. Influenza illness in European and Israeli children 2-17 years of age resulted in a considerable absenteeism and healthcare utilization that was similar across the countries studied. These data underscore the potential benefits of annual vaccination of children against influenza.

Seroepidemiologies of human metapneumovirus and respiratory syncytial virus in young children, determined with a new recombinant fusion protein enzyme-linked immunosorbent assay

We compared antibodies against human metapneumovirus (HMPV) and respiratory syncytial virus (RSV) in children. The antibody nadirs for both viruses were at 3 to 5 months, and the majority of children were seropositive for both by 2 years. There was no significant difference in the kinetics of maternal antibody decline or seroconversion relative to the two viruses.

Elucidation and clinical role of emerging viral respiratory tract infections in children

Acute respiratory viral infections (ARVI's) are the most common infectious disease in humans. With the appearance of molecular techniques the recovery of viruses has dramatically increased. Nowadays virologists can quickly discriminate virological families and related viruses from emerging viruses and consequently identify novel viruses. Many new respiratory viruses have been identified in children in the past 15 years. In this review we shortly discuss novel respiratory viruses and their pathogenic role in pediatric respiratory disease. Advantages and drawbacks of the technique and our current knowledge will be discussed. We will conclude this review with a general discussion on the future role of molecular diagnostic virology in the clinic.

Burden of paediatric influenza in Western Europe: a systematic review

Background

Influenza illness in children causes significant clinical and economic burden. Although some European countries have adopted influenza immunisation policies for healthy children, the debate about paediatric influenza vaccination in most countries of the European Union is ongoing. Our aim was to summarise influenza burden (in terms of health outcomes and economic burden) in children in Western Europe via a systematic literature review.

Methods

We conducted a systematic literature search of PubMed, EMBASE, and the Cochrane Library (1970-April 2011) and extracted data on influenza burden in children (defined as aged ≤ 18 years) from 50 publications (13 reporting laboratory-confirmed influenza; 37 reporting influenza-like illness).

Results

Children with laboratory-confirmed influenza experienced hospitalisations (0.3%-20%), medical visits (1.7-2.8 visits per case), antibiotic prescriptions (7%-55%), and antipyretic or other medications for symptomatic relief (76%-99%); young children and those with severe illness had the highest rates of health care use. Influenza in children also led to absenteeism from day care, school, or work for the children, their siblings, and their parents. Average (mean or median) length of absence from school or day care associated with confirmed influenza ranged from 2.8 to 12.0 days for the children, from 1.3 to 6.0 days for their siblings, and from 1.3 to 6.3 days for their parents. Influenza negatively affected health-related quality of life in children with asthma, including symptoms and activities; this negative effect was smaller in vaccinated children than in non-vaccinated children.

Conclusions

Influenza burden in children is substantial and has a significant direct impact on the ill children and an indirect impact on their siblings and parents. The identified evidence regarding the burden of influenza may help inform both influenza antiviral use in children and paediatric immunisation policies in European countries.

Fatal human metapneumovirus and influenza B virus coinfection in an allogeneic hematopoietic stem cell transplant recipient

Human metapneumovirus (hMPV) infection can occur in all age groups with significant morbidity and mortality. Coinfection with influenza virus occurs mainly with influenza type A and all reported cases recovered completely. We report the case of a 61-year-old man who had hematopoietic stem cell transplant for myelodysplastic syndrome. He was admitted to hospital for septic shock and neutropenia, and blood culture was positive for Pseudomonas aeruginosa. He rapidly developed respiratory failure and required ventilator support. His respiratory culture grew P. aeruginosa and hMPV. His course was complicated by persistent shock requiring vasopressor support, and repeat nasopharyngeal swab was positive for influenza type B and hMPV. His condition rapidly deteriorated, his family elected comfort care, and the patient died shortly thereafter. Coinfection with hMPV and influenza virus type B may have a poor outcome and can be fatal, especially in immunocompromised patients.

Increase human metapneumovirus mediated morbidity following pandemic influenza infection

Human metapneumovirus (hMPV) is a recently discovered respiratory pathogen, infecting mainly young children. The infected patients suffer from influenza like symptoms (ILS). In Israel the virus is mainly circulating in February to March. Here we report on an increased rate of hMPV infection in the winter season of 2009–10. The 2009–10 infection had several unique characteristics when compared to previous seasons; it started around January and a large number of infants were infected by the virus. Genetic analysis based on the viral L and F genes of hMPV showed that only subtypes A2 and B2 circulated in Israel. Additionally, we have identified a novel variant of hMPV within subgroup A2b, which subdivide it into A2b1 and A2b2. Finally, we showed that the hMPV infection was detected in the country soon after the infection with the pandemic influenza virus had declined, that infection with the pandemic influenza virus was dominant and that it interfered with the infection of other respiratory viruses. Thus, we suggest that the unusual increase in hMPV infection observed in 2009–10 was due to the appearance of the pandemic influenza virus in the winter season prior to 2009–10.

Human Metapneumovirus: lessons learned over the first decade

It has been 10 years since human metapneumovirus (HMPV) was identified as a causative agent of respiratory illness in humans. Since then, numerous studies have contributed to a substantial body of knowledge on many aspects of HMPV. This review summarizes our current knowledge on HMPV, HMPV disease pathogenesis, and disease intervention strategies and identifies a number of areas with key questions to be addressed in the future.

Isolation of influenza viruses in MDCK 33016PF cells and clearance of contaminating respiratory viruses

This paper summarizes results obtained by multiplex PCR screening of human clinical samples for respiratory viruses and corresponding data obtained after passaging of virus-positive samples in MDCK 33016PF cells. Using the ResPlexII v2.0 (Qiagen) multiplex PCR, 393 positive results were obtained in 468 clinical samples collected during an influenza season in Germany. The overall distribution of positive results was influenza A 42.0%, influenza B 38.7%, adenovirus 1.5%, bocavirus 0.5%, coronavirus 3.3%, enterovirus 5.6%, metapneumovirus 1.0%, parainfluenza virus 0.8%, rhinovirus 4.1%, and respiratory syncytial virus (RSV) 2.5%. Double infections of influenza virus together with another virus were found for adenovirus B and E, bocavirus, coronavirus, enterovirus and for rhinovirus. These other viruses were rapidly lost upon passages in MDCK 33016PF cells and under conditions as applied to influenza virus passaging. Clinical samples, in which no influenza virus but other viruses were found, were also subject to passages in MDCK 33016PF cells. Using lower inoculum dilutions than those normally applied for preparations containing influenza virus (total dilution of the original sample of ∼10⁴), the positive results for the different viruses turned negative already after 2 or 3 passages in MDCK 33016PF cells. These results demonstrate that, under practical conditions as applied to grow influenza viruses, contaminating viruses can be effectively removed by passages in MDCK cells. In combination with their superior isolation efficiency, MDCK cells appear highly suitable to be used as an alternative to embryonated eggs to isolate and propagate influenza vaccine candidate viruses.

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.

Viruses and bacteria in acute asthma exacerbations--a GA² LEN-DARE systematic review

To cite this article: Papadopoulos NG, Christodoulou I, Rohde G, Agache I, Almqvist C, Bruno A, Bonini S, Bont L, Bossios A, Bousquet J, Braido F, Brusselle G, Canonica GW, Carlsen KH, Chanez P, Fokkens WJ, Garcia‐Garcia M, Gjomarkaj M, Haahtela T, Holgate ST, Johnston SL, Konstantinou G, Kowalski M, Lewandowska‐Polak A, Lødrup‐Carlsen K, Mäkelä M, Malkusova I, Mullol J, Nieto A, Eller E, Ozdemir C, Panzner P, Popov T, Psarras S, Roumpedaki E, Rukhadze M, Stipic‐Markovic A, Todo Bom A, Toskala E, van Cauwenberge P, van Drunen C, Watelet JB, Xatzipsalti M, Xepapadaki P, Zuberbier T. Viruses and bacteria in acute asthma exacerbations – A GA²LEN‐DARE systematic review. Allergy 2011; 66: 458–468.

Abstract

A major part of the burden of asthma is caused by acute exacerbations. Exacerbations have been strongly and consistently associated with respiratory infections. Respiratory viruses and bacteria are therefore possible treatment targets. To have a reasonable estimate of the burden of disease induced by such infectious agents on asthmatic patients, it is necessary to understand their nature and be able to identify them in clinical samples by employing accurate and sensitive methodologies. This systematic review summarizes current knowledge and developments in infection epidemiology of acute asthma in children and adults, describing the known impact for each individual agent and highlighting knowledge gaps. Among infectious agents, human rhinoviruses are the most prevalent in regard to asthma exacerbations. The newly identified type‐C rhinoviruses may prove to be particularly relevant. Respiratory syncytial virus and metapneumovirus are important in infants, while influenza viruses seem to induce severe exacerbations mostly in adults. Other agents are relatively less or not clearly associated. Mycoplasma and Chlamydophila pneumoniae seem to be involved more with asthma persistence rather than with disease exacerbations. Recent data suggest that common bacteria may also be involved, but this should be confirmed. Although current information is considerable, improvements in detection methodologies, as well as the wide variation in respect to location, time and populations, underline the need for additional studies that should also take into account interacting factors.

Altered cardiac rhythm in infants with bronchiolitis and respiratory syncytial virus infection

Background

Although the most frequent extra-pulmonary manifestations of respiratory syncytial virus (RSV) infection involve the cardiovascular system, no data regarding heart function in infants with bronchiolitis associated with RSV infection have yet been systematically collected. The aim of this study was to verify the real frequency of heart involvement in patients with bronchiolitis associated with RSV infection, and whether infants with mild or moderate disease also risk heart malfunction.

Methods

A total of 69 otherwise healthy infants aged 1-12 months with bronchiolitis hospitalised in standard wards were enrolled. Pernasal flocked swabs were performed to collect specimens for the detection of RSV by real-time polymerase chain reaction, and a blood sample was drawn to assess troponin I concentrations. On the day of admission, all of the infants underwent 24-hour Holter ECG monitoring and a complete heart evaluation with echocardiography. Patients were re-evaluated by investigators blinded to the etiological and cardiac findings four weeks after enrolment.

Results

Regardless of their clinical presentation, sinoatrial blocks were identified in 26/34 RSV-positive patients (76.5%) and 1/35 RSV-negative patients (2.9%) (p < 0.0001). The blocks recurred more than three times over 24 hours in 25/26 RSV-positive patients (96.2%) and none of the RSV-negative infants. Mean and maximum heart rates were significantly higher in the RSV-positive infants (p < 0.05), as was low-frequency power and the low and high-frequency power ratio (p < 0.05). The blocks were significantly more frequent in the children with an RSV load of ≥100,000 copies/mL than in those with a lower viral load (p < 0.0001). Holter ECG after 28 ± 3 days showed the complete regression of the heart abnormalities.

Conclusions

RSV seems associated with sinoatrial blocks and transient rhythm alterations even when the related respiratory problems are mild or moderate. Further studies are needed to clarify the mechanisms of these rhythm problems and whether they remain asymptomatic and transient even in presence of severe respiratory involvement or chronic underlying disease.

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.

Human metapneumovirus in hospitalized children in Amman, Jordan

Human metapneumovirus (HMPV) has recently been identified as an important cause of acute respiratory infections (ARI) in children worldwide. However, there is little systematic data on its frequency and importance as a cause of ARI in the Middle East. We conducted a viral surveillance study in children <5 years of age admitted with respiratory symptoms and/or fever at two major tertiary care hospitals in Amman, Jordan from 1/18-3/29/07. Nose and throat swabs were collected and tested for HMPV and other respiratory viruses by real-time RT-PCR. A total of 743 subjects were enrolled. Forty-four (6%) subjects were positive for HMPV, 467 (64%) were positive for RSV and 13 (1.3%) had co-infection with both HMPV and RSV. The frequency of HMPV in January, February, and March was 4.1%, 3.0%, and 11.9% respectively. Clinical features associated with HMPV infection were similar to those of other respiratory viruses, except children with HMPV were more likely to present with fever than children not infected with HMPV. Children with HMPV and RSV co-infection were administered supplemental oxygen and were admitted to the ICU more frequently than children infected with HMPV alone or RSV alone, though these differences did not reach statistical significance. We conclude that HMPV is an important cause of acute respiratory infections in children in Amman, Jordan. Longer surveillance studies are needed to better understand the seasonal epidemiology of HMPV and to assess if co-infection with HMPV and RSV leads to more severe illness.

Role of emerging respiratory viruses in children with severe acute wheezing

BACKGROUND

Acute wheezing episodes are frequently associated with respiratory viral infections in children. However, the role of the recently described respiratory viruses is not yet fully understood.

OBJECTIVE

The main objective of this study was to estimate the frequency of human metapneumovirus (HMPV), human bocavirus (HBoV), and 14 other respiratory viruses in hospitalized children with acute wheezing.

METHODS

A prospective study was conducted on children <14 years old, admitted with an acute expiratory wheezing episode from September 2005 to June 2008. Viruses were detected in nasopharyngeal aspirates by polymerase chain reaction. Clinical data were prospectively recorded.

RESULTS

A viral pathogen was identified in 444 (71%) out of 626 hospitalized acute wheezing episodes. Respiratory syncytial virus (RSV) was the most frequently detected (27%), followed by rhinovirus (24%), adenovirus (17.8%), HBoV (16%), and HMPV (4.7%). The rate of viral detection was significantly higher in infants (77.3%), than in older children (59.8%) (P < 0.001). RSV and HBoV were more prevalent in infants (P < 0.001) than in older children.

CONCLUSION

The most prevalent viruses found in severe acute wheezing episodes were RSV and rhinovirus not only in childhood, but also in infancy. However, other emerging viruses such as HBoV and metapneumovirus also play an important role in wheezing episodes.