Antigen-based assays for the identification of influenza virus and respiratory syncytial virus: why and how to use them in pediatric practice

Prognosis of hospitalized children under 2 years of age with co-detection of influenza A and respiratory syncytial virus at the healthcare facility

Abstract Objectives: the aim of this study is to evaluate the impact of co-detection of Flu A and RSV using rapid immunochromatographic tests at the point of care, in pediatric patients under 2 years of age in a general hospital. Methods: a retrospective cohort study was conducted to analyze clinical outcomes in hospitalized infants with viral respiratory disease with positive results of rapid immunochromatographic test for RSV and/or Flu-A, from 2013 to 2018. A logistic regression model was adjusted to analyze predictors of orotracheal intubation during hospitalization. Results: we analyzed 220 cases: RSV (192), Flu-A (9), co-detection (19). Lethality rate was 1.8% (2 cases), and 88% (194) were under 1 year of age. Mean time of hospitalizations was higher in patients with co-detection. Variables significantly associated with orotracheal intubation were: younger age in months, comorbidities, RSV and Flu-A co-detection, and bacterial pneumonia during hospitalization. Conclusions: RSV and Flu-Aco-detection was associated with the least favorable clinical prognoses in this study. Rapid test diagnosis may provide important information at the point of care, because molecular panels are not widely accessible in general hospitals. Rapid diagnosis allows timely evaluation and treatment.

Respiratory RNA Viruses

Acute upper and lower respiratory infections are a major public health problem and a leading cause of morbidity and mortality worldwide. At greatest risk are young children, the elderly, the chronically ill, and those with suppressed or compromised immune systems. Viruses are the predominant cause of respiratory tract illnesses and include RNA viruses such as respiratory syncytial virus, influenza virus, parainfluenza virus, metapneumovirus, rhinovirus, and coronavirus. Laboratory testing is required for a reliable diagnosis of viral respiratory infections, as a clinical diagnosis can be difficult since signs and symptoms are often overlapping and not specific for any one virus. Recent advances in technology have resulted in the development of newer diagnostic assays that offer great promise for rapid and accurate detection of respiratory viral infections. This chapter emphasizes the fundamental characteristics and clinical importance of the various RNA viruses that cause upper and lower respiratory tract diseases in the immunocompromised host. It highlights the laboratory methods that can be used to make a rapid and definitive diagnosis for the greatest impact on the care and management of ill patients, and the prevention and control of hospital-acquired infections and community outbreaks.

Prevalence of co-infection between respiratory syncytial virus and influenza in children

BACKGROUND

Respiratory syncytial virus (RSV) and influenza have varying degree of seasonal overlap.

OBJECTIVE

To determine the prevalence of co-infection of RSV and influenza compared to the prevalence of those infections independently when both are in season.

METHODS

This was a retrospective cross-sectional study of children evaluated between July 2010 and June 2013 for viral respiratory infection using multiplex PCR. Seasonality was defined retrospectively as weeks when >2% of the total annual positive tests were obtained and was calculated for influenza A, influenza B, and RSV independently. Periods of overlapping seasonality of RSV and influenza A and RSV and influenza B were identified. The expected incidences of co-infection were modeled as the product of the incidences of the individual viruses.

RESULTS

13,664 specimens were sent for PCR during the study period. Over all 3 seasons, RSV overlapped with influenza A and B for 22 and 18weeks, respectively; in 2011-12, RSV overlapped with neither influenza A nor B. Based on modeling, there were 6-7 fold fewer cases of RSV/influenza co-infection observed than expected: RSV/influenza A 77 vs. 12, (p≤0.001; RSV/influenza B 76 vs. 11 (p≤0.001).

CONCLUSIONS

The observed incidence of co-infectivity of RSV and influenza was significantly less than the expected incidence even when both were co-circulating. In light of these data, it may be reasonable to forgo rapid influenza testing or empiric antiviral treatment for children whom rapid RSV testing is positive and who are at low risk of influenza-related complications, especially in times of antiviral therapy shortages.

Performance evaluation of a rapid molecular diagnostic, MultiCode based, sample-to-answer assay for the simultaneous detection of Influenza A, B and respiratory syncytial viruses

BACKGROUND

Clinical signs and symptoms of different airway pathogens are generally indistinguishable, making laboratory tests essential for clinical decisions regarding isolation and antiviral therapy. Immunochromatographic tests (ICT) and direct immunofluorescence assays (DFA) have lower sensitivities and specificities than molecular assays, but have the advantage of quick turnaround times and ease-of-use.

OBJECTIVE

To evaluate the performance of a rapid molecular assay, ARIES FluA/B & RSV, using laboratory developed RT-PCR assays (LDA), ICT (BinaxNOW) and DFA.

METHODS

Analytical and clinical performance were evaluated in a retrospective study arm (stored respiratory samples obtained between 2006-2015) and a prospective study arm (unselected fresh clinical samples obtained between December 2015 and March 2016 tested in parallel with LDAs).

RESULTS

Genotype inclusivity and analytical specificity was 100%. However, ARIES was 0.5 log, 1-2logs and 2.5logs less sensitive for fluA, RSV and fluB respectively, compared to LDA. In total, 447 clinical samples were included, of which 15.4% tested positive for fluA, 9.2% for fluB and 26.0% for RSV, in both LDA and ARIES. ARIES clinical sensitivity compared to LDA was 98.6% (fluA), 93.3% (fluB) and 95.1% (RSV). Clinical specificity was 100% for all targets. ARIES detected 10.6% (4 fluA, 8 fluB, 11 RSV) and 26.9% (7 fluA, 3 fluB, 22 RSV) more samples compared to DFA and ICT, all confirmed by LDA.

CONCLUSION

Although analytically ARIES is less sensitive than LDA, the clinical performance of the assay in our tertiary care setting was comparable, and significantly better than that of the established rapid assays.

Antimicrobial stewardship in paediatrics

BACKGROUND

Antibiotics are among the drugs most commonly prescribed to children in hospitals and communities. Unfortunately, a great number of these prescriptions are unnecessary or inappropriate. Antibiotic abuse and misuse have several negative consequences, including drug-related adverse events, the emergence of multidrug resistant bacterial pathogens, the development of Clostridium difficile infection, the negative impact on microbiota, and undertreatment risks. In this paper, the principle of and strategies for paediatric antimicrobial stewardship (AS) programs, the effects of AS interventions and the common barriers to development and implementation of AS programs are discussed.

DISCUSSION

Over the last few years, there have been significant shortages in the development and availability of new antibiotics; therefore, the implementation of strategies to preserve the activity of existing antimicrobial agents has become an urgent public health priority. AS is one such approach. The need for formal AS programs in paediatrics was officially recognized only recently, considering the widespread use of antibiotics in children and the different antimicrobial resistance patterns that these subjects exhibit in comparison to adult and elderly patients. However, not all problems related to the implementation of AS programs among paediatric patients are solved. The most important remaining problems involve educating paediatricians, creating a multidisciplinary interprofessional AS team able to prepare guidelines, monitoring antibiotic prescriptions and defining corrective measures, and the availability of administrative consensuses with adequate financial support. Additionally, the problem of optimizing the duration of AS programs remains unsolved. Further studies are needed to solve the above mentioned problems.

CONCLUSIONS

In paediatric patients, as in adults, the successful implementation of AS strategies has had a significant impact on reducing targeted- and nontargeted-antimicrobial use by improving the quality of care for hospitalized patients and preventing the emergence of resistance. Considering that rationalization of antibiotic misuse and abuse is the basis for reducing emergence of bacterial resistance and several clinical problems, all efforts must be made to develop multidisciplinary paediatric AS programs in hospital and community settings.

Antivirals for Respiratory Viral Infections: Problems and Prospects

In the past two decades, several newly emerging and reemerging viral respiratory pathogens including several influenza viruses (avian influenza and pandemic influenza), severe acute respiratory syndrome coronavirus (SARS-CoV), and Middle East respiratory syndrome coronavirus (MERS-CoV), have continued to challenge medical and public health systems. Thereafter, the development of cost-effective, broad-spectrum antiviral agents is the urgent mission of both virologists and pharmacologists. Current antiviral developments have focused targets on viral entry, replication, release, and intercellular pathways essential for viral life cycle. Here, we review the current literature on challenges and prospects in the development of these antivirals.

Diagnostic performance of influenza viruses and RSV rapid antigen detection tests in children in tertiary care

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The here studied rapid antigen detection test (RADT) BinaxNOW RSV has a high sensitivity and positive predictive value.

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RADT BinaxNOW Influenza A&B has a relatively low sensitivity and positive predictive value.

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We advise a restricted use of RADT BinaxNOW Influenza A&B in a tertiary paediatric care setting.

Background

Rapid antigen detection tests (RADTs) are increasingly used to detect influenza viruses and respiratory syncytial virus (RSV). However, their sensitivity and specificity are a matter of debate, challenging their clinical usefulness.

Objectives

Comparing diagnostic performances of BinaxNow Influenza AB^® (BNI) and BinaxNow RSV^® (BNR), to those of real-time reverse transcriptase PCR (RT-PCR), virus isolation and direct immunofluorescence (D-IF) in paediatric patients.

Study design

Between November 2005 and September 2013, 521 nasal washings from symptomatic children (age <5 years) attending our tertiary care centre were tested, with a combination of the respective assays using RT-PCR as gold standard.

Results

Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of BNI were 69% (confidence interval [CI] [51–83]), 96% [94–97], 55% [39–70] and 98% [96–99] respectively. Of eleven false-negative samples, RT-PCR Ct-values were higher than all RT-PCR positive test results (27 vs 22, p = 0.012). Of twenty false-positive samples, none were culture positive and two tested positive in D-IF.

Sensitivity, specificity, PPV and NPV for BNR were 79% [73–85], 98% [96–99], 97% [93–99] and 88% [84–91]. Of the 42 false-negative samples the median Ct-value was higher than that of all RT-PCR positive samples (31 vs 23, p < 0.0001). Five false-positive samples were detected. Three of these tested positive for RSV in virus isolation and D-IF.

Conclusions

RADTs have a high specificity with BNR being superior to BNI. However, their relative low sensitivity limits their usefulness for clinical decision making in a tertiary care paediatric hospital.

Viral Infection in the Development and Progression of Pediatric Acute Respiratory Distress Syndrome

Viral infections are an important cause of pediatric acute respiratory distress syndrome (ARDS). Numerous viruses, including respiratory syncytial virus (RSV) and influenza A (H1N1) virus, have been implicated in the progression of pneumonia to ARDS; yet the incidence of progression is unknown. Despite acute and chronic morbidity associated with respiratory viral infections, particularly in "at risk" populations, treatment options are limited. Thus, with few exceptions, care is symptomatic. In addition, mortality rates for viral-related ARDS have yet to be determined. This review outlines what is known about ARDS secondary to viral infections including the epidemiology, the pathophysiology, and diagnosis. In addition, emerging treatment options to prevent infection, and to decrease disease burden will be outlined. We focused on RSV and influenza A (H1N1) viral-induced ARDS, as these are the most common viruses leading to pediatric ARDS, and have specific prophylactic and definitive treatment options.

[Interests and limitations of rapid diagnostic tests for respiratory and gastrointestinal viral diseases]

Les tests de dépistage rapide (TDR) basés sur la technique d’immunochromatographie sont très répandus pour le diagnostic des maladies infectieuses. Dans le cadre des infections respiratoires virales, il s’agit essentiellement de tests pour le diagnostic de la grippe et des infections à virus respiratoire syncytial (VRS). Pour le diagnostic des gastroentérites virales, ce sont des tests de détection des rotavirus, adénovirus, norovirus et astrovirus qui peuvent être utilisés. Les TDR pour les infections à VRS et les gastroentérites sont utilisés essentiellement dans le cadre de la pathologie pédiatrique. Ces tests présentent généralement une spécificité élevée mais une sensibilité modeste par rapport aux techniques moléculaires. Ce sont donc surtout des tests de dépistages et leur négativité ne permet pas d’exclure le diagnostic.

Challenges and opportunities in developing respiratory syncytial virus therapeutics

Two meetings, one sponsored by the Wellcome Trust in 2012 and the other by the Global Virology Foundation in 2013, assembled academic, public health and pharmaceutical industry experts to assess the challenges and opportunities for developing antivirals for the treatment of respiratory syncytial virus (RSV) infections. The practicalities of clinical trials and establishing reliable outcome measures in different target groups were discussed in the context of the regulatory pathways that could accelerate the translation of promising compounds into licensed agents. RSV drug development is hampered by the perceptions of a relatively small and fragmented market that may discourage major pharmaceutical company investment. Conversely, the public health need is far too large for RSV to be designated an orphan or neglected disease. Recent advances in understanding RSV epidemiology, improved point-of-care diagnostics, and identification of candidate antiviral drugs argue that the major obstacles to drug development can and will be overcome. Further progress will depend on studies of disease pathogenesis and knowledge provided from controlled clinical trials of these new therapeutic agents. The use of combinations of inhibitors that have different mechanisms of action may be necessary to increase antiviral potency and reduce the risk of resistance emergence.

Evaluation of novel second-generation RSV and influenza rapid tests at the point of care

Acute respiratory infections represent common pediatric emergencies. Infection control warrants immediate and accurate diagnoses. In the past, first-generation respiratory syncytial virus (RSV) rapid tests (strip tests) have shown suboptimal sensitivities. In 2013, the Food and Drug Administration licensed a second-generation RSV rapid test providing user-independent readouts (SOFIA™-RSV) using automated fluorescence assay technology known to yield superior results with influenza rapid testing. We are reporting the first point-of-care evaluation of the SOFIA™-RSV rapid test. In the Charité Influenza-Like Disease Cohort, 686 nasopharyngeal samples were tested in parallel with SOFIA™-RSV and SOFIA™-Influenza A+B. Compared to real-time PCR, SOFIA™-RSV sensitivities/specificities were 78.6%/93.9%, respectively (SOFIA™-Influenza A: 80.6%/99.3%). Performance was greatest in patients below 2 years of age with a test sensitivity of 81.8%. RSV sensitivities were highest (85%) in the first 2 days of illness and with nasopharyngeal compared to nasal swabs (P=0.055, McNemar's test). Second-generation RSV and influenza rapid testing provides highly accurate results facilitating timely patient cohortation and management.

Screening for respiratory syncytial virus and isolation strategies in children hospitalized with acute respiratory tract infection

Nosocomial infection with respiratory syncytial virus (RSV) is an important health risk in pediatric care but is largely preventable by efficient infection control measures. Commonly applied rapid antigen detection tests (RADTs) miss a considerable number of RSV-infected patients. The objective of our analysis was to evaluate whether readily available host parameters are associated with false-negative RADT, and to assess how these parameters could be applied in an optimized RSV isolation strategy.We retrospectively analyzed a cohort of 242 children under the age of 2 years hospitalized with acute respiratory tract infection to identify host parameters associated with false-negative RADT test result. We subsequently simulated the outcome of different isolation strategies based on RADT result and host parameters in view of the overall isolation efficacy.Out of 242 hospitalized patients, 134 (55%) patients were found RSV-positive by RT-PCR, whereas 108 (45%) patients were tested negative. The performance of the RADT was compared with the result obtained by reverse transcription polymerase chain reaction on the identical nasopharyngeal wash. Overall, we found that 85 patients (35%) were tested true positive, 108 (45%) were tested true negative, whereas a false-negative test result was obtained in 49 patients (20%). Duration of respiratory symptoms for >3 days and a respiratory admission diagnosis are associated with false-negative RADT result. In comparison with RADT alone, consideration of these clinical parameters and RADT result can decrease the rate of nonisolated RSV-infected patients from approximately 24% to 8% (65% RSV pretest probability).Consideration of both RADT and clinical parameters associated with false-negative RADT can result in an optimized RSV infection control policy.

Inter-society consensus document on treatment and prevention of bronchiolitis in newborns and infants

Acute bronchiolitis is the leading cause of lower respiratory tract infection and hospitalization in children less than 1 year of age worldwide. It is usually a mild disease, but some children may develop severe symptoms, requiring hospital admission and ventilatory support in the ICU. Infants with pre-existing risk factors (prematurity, bronchopulmonary dysplasia, congenital heart diseases and immunodeficiency) may be predisposed to a severe form of the disease. Clinical diagnosis of bronchiolitis is manly based on medical history and physical examination (rhinorrhea, cough, crackles, wheezing and signs of respiratory distress). Etiological diagnosis, with antigen or genome detection to identify viruses involved, may have a role in reducing hospital transmission of the infection. Criteria for hospitalization include low oxygen saturation (<90-92%), moderate-to-severe respiratory distress, dehydration and presence of apnea. Children with pre-existing risk factors should be carefully assessed.To date, there is no specific treatment for viral bronchiolitis, and the mainstay of therapy is supportive care. This consists of nasal suctioning and nebulized 3% hypertonic saline, assisted feeding and hydration, humidified O2 delivery. The possible role of any pharmacological approach is still debated, and till now there is no evidence to support the use of bronchodilators, corticosteroids, chest physiotherapy, antibiotics or antivirals. Nebulized adrenaline may be sometimes useful in the emergency room. Nebulized adrenaline can be useful in the hospital setting for treatment as needed. Lacking a specific etiological treatment, prophylaxis and prevention, especially in children at high risk of severe infection, have a fundamental role. Environmental preventive measures minimize viral transmission in hospital, in the outpatient setting and at home. Pharmacological prophylaxis with palivizumab for RSV bronchiolitis is indicated in specific categories of children at risk during the epidemic period. Viral bronchiolitis, especially in the case of severe form, may correlate with an increased incidence of recurrent wheezing in pre-schooled children and with asthma at school age.The aim of this document is to provide a multidisciplinary update on the current recommendations for the management and prevention of bronchiolitis, in order to share useful indications, identify gaps in knowledge and drive future research.

Evaluation of Alere i Influenza A&B for rapid detection of influenza viruses A and B

Rapid and accurate diagnosis of influenza is important for infection control, as well as for patient management. Alere i Influenza A&B is an isothermal nucleic acid amplification-based integrated system for detection and differentiation of influenza virus A and influenza virus B. The performance of the Alere i Influenza A&B was screened using frozen nasopharyngeal-swab specimens collected in viral transport medium (VTM) that were originally tested fresh with the FilmArray Respiratory Panel (RP) assay during the 2012-2013 influenza outbreak. In total, 360 VTM specimens were selected for Alere i Influenza A&B testing: 40 influenza virus A H1N1-2009 (influenza virus A-1), 40 influenza virus A H3N2 (influenza virus A-3), 37 influenza virus A "equivocal" or "no subtype detected" (influenza virus A-u), 41 influenza virus B, and 202 influenza virus-negative specimens, as initially determined by the FilmArray RP assay. The Alere assay showed sensitivities of 87.2%, 92.5%, 25.0%, and 97.4% for influenza virus A-1, influenza virus A-3, influenza virus A-u, and influenza virus B, respectively, after discordant resolution by Prodesse ProFLU+ PCR. The specificities were 100% for both influenza virus A and influenza virus B. In general, the Alere i Influenza A&B provided good sensitivity, although the assay did show poorer sensitivity with samples determined to have low influenza virus A titers by Prodesse ProFlu+ PCR (a mean real-time PCR threshold cycle [CT] value of 31.9 ± 2.0), which included the majority of the samples called influenza virus A "equivocal" or "no subtype detected" by a single BioFire FilmArray RP test. The integrated, rapid, and simple characteristics of the Alere i Influenza A&B assay make it a potential candidate for point-of-care testing, with a test turnaround time of less than 15 min.

Host and viral factors affecting clinical performance of a rapid diagnostic test for respiratory syncytial virus in hospitalized children

Respiratory syncytial virus rapid antigen detection tests (RADT) are used widely. RADT exhibited high specificity (97%) and moderate sensitivity (80%) compared with reverse-transcriptase polymerase chain reaction in 720 hospitalized children <3 years old. Older age, prolonged symptoms, and respiratory syncytial virus genotype-B infection were significantly associated with false-negative results of RADT.

Delayed RSV diagnosis in a stem cell transplant population due to mutations that result in negative polymerase chain reaction

Respiratory syncytial virus (RSV) is a serious cause of morbidity and mortality in the adult hematopoietic stem cell transplant (HSCT) population. The timely diagnosis of RSV infection in this population is important for initiating therapy and instituting appropriate infection prevention measures. Molecular multiplex assays now offer increased sensitivity for a more accurate diagnosis. This study presents 5 cases of RSV infection in HSCT patients in which diagnosis was delayed due to false-negative results from a multiplex polymerase chain reaction (PCR) assay. The false-negative result was due to a single base-pair mutation in the RSV strain. These false results delayed the appropriate treatment of patients. This study shows that a combination of a multiplex PCR assay, viral antigen, and/or culture should be used to detect variants of RSV in patients and that multiplex respiratory viral assays should develop a more robust design that includes multiple genetic target per virus to prevent missing viruses that continue to have genetic variances.

Spectrum of viral infections in patients with cystic fibrosis

This review explores the extensive influence of viral infections leading to chronic deterioration of lung function in patients with cystic fibrosis (CF). The mechanisms how viral agents affect the pathogenesis as well as the inflammatory and immune response of CF are discussed. Viral infections of the upper and lower respiratory tract due to viruses in CF patients and methods for diagnosis of respiratory viruses are described in detail. The importance of respiratory and non-respiratory viral agents for the pathogenesis, especially for the exacerbation of bacterial lower respiratory tract infections and course of CF, is stressed, especially emphasizing respiratory syncytial virus, influenza virus, rhinovirus, and human herpes viruses. Possible harmful effects of further viruses like adenovirus, bocavirus, coronavirus, metapneumovirus, parainfluenzavirus on the lung function of CF patients are discussed. The potential use of adenovirus-based vectors for somatic gene therapy is mentioned.

Impact of viral infections in children with community-acquired pneumonia: results of a study of 17 respiratory viruses

Please cite this paper as: Esposito et al. (2012) Impact of viral infections in children with community‐acquired pneumonia: results of a study of 17 respiratory viruses. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2012.00340.x.

Background  Little is known about the prevalence of viral infections in children with community‐acquired pneumonia (CAP).

Objectives  To describe the clinical and virological data collected from children with radiographically confirmed CAP in whom 17 respiratory viruses were sought in respiratory secretion samples during the acute phase of the disease.

Patients and methods  The study involved 592 children with radiographically confirmed CAP whose respiratory secretion samples were tested using the Luminex xTAG Respiratory Virus Panel Fast assay, which simultaneously detects influenza A virus, influenza B virus, respiratory syncytial virus (RSV)‐A and ‐B, parainfluenzavirus‐1, ‐2, ‐3, and ‐4, adenovirus, human metapneumovirus, coronaviruses 229E, NL63, OC43, and HKU1, enterovirus/rhinovirus, and bocavirus. A real‐time PCR assay was used to identify the rhinovirus in the enterovirus/rhinovirus‐positive samples.

Results  A total of 435 children (73·5%) were positive for at least one virus: the most frequently detected was RSV, which was found in 188 (31·7%), followed by rhinovirus (n = 144, 24·3%), bocavirus (n = 60, 10·1%), influenza viruses (n = 57, 9·6), and hMPV (n = 49, 8·2%). Viral co‐infections were found in 117 children (19·7% of the enrolled children; 26·9% of those with viral infections). Marginal differences were found between the infections owing to a single virus. Co‐infections showed radiographic evidence of alveolar pneumonia significantly more frequently than single infections (OR 1·72, 95% CI 1·05–2·81).

Conclusions  The findings of this study highlight the importance of respiratory viruses (mainly RSV and rhinovirus) in children with CAP and show the characteristics of both the single infections and co‐infections associated with the disease.

Clinical and socioeconomic impact of different types and subtypes of seasonal influenza viruses in children during influenza seasons 2007/2008 and 2008/2009

Background

There are few and debated data regarding possible differences in the clinical presentations of influenza A/H1N1, A/H3N2 and B viruses in children. This study evaluates the clinical presentation and socio-economic impact of laboratory-confirmed influenza A/H1N1, A/H3N2 or B infection in children attending an Emergency Room because of influenza-like illness.

Methods

Among the 4,726 children involved, 662 had influenza A (143 A/H1N1 and 519 A/H3N2) and 239 influenza B infection detected by means of real-time polymerase chain reaction. Upon enrolment, systematic recordings were made of the patients' demographic characteristics and medical history using standardised written questionnaires. The medical history of the children was re-evaluated 5-7 days after enrolment and until the resolution of their illness by means of interviews and a clinical examination by trained investigators using standardised questionnaires. During this evaluation, information was also obtained regarding illnesses and related morbidity among households.

Results

Children infected with influenza A/H1N1 were significantly younger (mean age, 2.3 yrs) than children infected with influenza A/H3N2 (mean age, 4.7 yrs; p < 0.05)) or with influenza B (mean age, 5.2 yrs; p < 0.05). Adjusted for age and sex, children with influenza A/H3N2 in comparison with those infected by either A/H1N1 or with B influenza virus were more frequently affected by fever (p < 0.05) and lower respiratory tract involvement (p < 0.05), showed a worse clinical outcome (p < 0.05), required greater drug use (p < 0.05), and suffered a worse socio-economic impact (p < 0.05). Adjusted for age and sex, children with influenza B in comparison with those infected by A/H1N1 influenza virus had significantly higher hospitalization rates (p < 0.05), the households with a disease similar to that of the infected child (p < 0.05) and the need for additional household medical visits (p < 0.05).

Conclusions

Disease due to influenza A/H3N2 viral subtype is significantly more severe than that due to influenza A/H1N1 subtype and influenza B virus, which indicates that the characteristics of the different viral types and subtypes should be adequately considered by health authorities when planning preventive and therapeutic measures.

Impact of perioperative RSV or influenza infection on length of stay and risk of unplanned ICU admission in children: a case-control study

Background

Children with viral respiratory infections who undergo general anesthesia are at increased risk of respiratory complications. We investigated the impact of RSV and influenza infection on perioperative outcomes in children undergoing general anesthesia.

Methods

We performed a retrospective case-control study. All patients under the age of 18 years who underwent general anesthesia at our institution with confirmed RSV or influenza infection diagnosed within 24 hours following induction between October 2002 and September 2008 were identified. Controls were randomly selected and were matched by surgical procedure, age, and time of year in a ratio of three controls per case. The primary outcome was postoperative length of stay (LOS).

Results

Twenty-four patients with laboratory-confirmed RSV or influenza who underwent general anesthesia prior to diagnosis of viral infection were identified and matched to 72 controls. Thirteen cases had RSV and 11 had influenza. The median postoperative LOS was three days (intra-quartile range 1 to 8 days) for cases and two days (intra-quartile range 1 to 5 days) for controls. Patients with influenza had a longer postoperative LOS (p < 0.001) and patients with RSV or influenza were at increased risk of unplanned admission to the PICU (p = 0.04) than matched controls.

Conclusions

Our results suggest that children with evidence of influenza infection undergoing general anesthesia, even in the absence of symptoms previously thought to be associated with a high risk of complications, may have a longer postoperative hospital LOS when compared to matched controls. RSV and influenza infection was associated with an increased risk of unplanned PICU admission.

Impact of the viral respiratory season on postoperative outcomes in children undergoing cardiac surgery

To compare postoperative outcomes in children undergoing cardiac surgery during the viral respiratory season and nonviral season at our institution. This was a retrospective cohort study and secondary matched case-control analysis. The setting was an urban academic tertiary-care children's hospital. The study was comprised of all patients <18 years of age who underwent cardiac surgery at Johns Hopkins Hospital from October 2002 through September 2007. Patients were stratified by season of surgery, complexity of cardiac disease, and presence or absence of viral respiratory infection. Measurements included patient characteristics and postoperative outcomes. The primary outcome was postoperative length of stay (LOS). A total of 744 patients were included in the analysis. There was no difference in baseline characteristics or outcomes, specifically, no difference in postoperative LOS, intensive care unit (ICU) LOS, and mortality, among patients by seasons of surgery. Patients with viral respiratory illness were more likely to have longer postoperative LOS (p < 0.01) and ICU LOS (p < 0.01) compared with matched controls. We identified no difference in postoperative outcomes based on season in patients undergoing cardiac surgery. Children with viral respiratory infection have significantly worse outcomes than matched controls, strengthening the call for universal administration of influenza vaccination and palivizumab to appropriate groups. Preoperative testing for respiratory viruses should be considered during the winter months for children undergoing elective cardiac surgery.

Advances in the diagnosis of respiratory tract infections: role of the Luminex xTAG respiratory viral panel

Clinical laboratories providing an etiological diagnosis of respiratory tract infections (RTI) have increasingly relied on nucleic acid amplification tests. Polymerase chain reaction‐based methods are becoming more standardized, and several have undergone the scrutiny of regulatory agencies mandated to assess the risks and benefits of implementing pathogen‐detection assays into diagnostic algorithms. Respiratory viruses lead to both upper and lower RTI and are implicated in exacerbations of chronic pulmonary conditions. Viruses from different taxonomic families present with overlapping clinical signs and symptoms, necessitating an accurate laboratory diagnosis. The clinical utility of diagnostic algorithms incorporating tests for respiratory viruses will depend on the breadth of pathogen coverage and the time to reliable and actionable results. This review covers strategies for detecting a panel of respiratory viruses employed over the last decade that have enabled an etiological diagnosis of RTI in a cost‐effective manner.

Viral agents causing lower respiratory tract infections in hospitalized children: evaluation of the Speed-Oligo® RSV assay for the detection of respiratory syncytial virus

Respiratory syncytial virus (RSV) is the viral agent which is more frequently involved in lower respiratory tract infections (LRTIs) in infants under 1 year of age in developed countries. A new oligochromatographic assay, Speed-Oligo® RSV, was designed and optimized for the specific detection and identification of RSV subtypes A and B. The test was evaluated in 289 clinical samples from 169 hospitalized children using an immunochromatography (IC) test, virus isolation by culture, and an in-house real-time polymerase chain reaction (RT-PCR). Other viruses causing LRTIs were investigated by cell culture or PCR-based tests. Sixty-two patients were infected by RSV (36.7%). In addition, adenovirus, influenza B, parainfluenza 2, and human metapneumovirus were detected in rates ranging from 5 to 8%. A proportion of 10.1% of the patients had mixed infections. The sensitivity, specificity, and positive and negative predictive values were, respectively, 94.9, 99.4, 98.9, and 97.4% for Speed-Oligo® RSV, 92.9, 96.3, 92.9, and 96.3% for RT-PCR/RSV, and 58.4, 98.1, 93.3, and 82.6% for IC. Our rates of viral detection and co-infection were similar to those of previously reported series. Finally, we find that Speed-Oligo® RSV is a rapid and easy-to-perform technique for the detection of RSV and the identification of subtypes A and B.

Clinical manifestations and socio-economic impact of influenza among healthy children in the community

OBJECTIVES

To evaluate the total burden of influenza among healthy children in the community in order to analyse the cost of influenza in paediatric age.

METHODS

This prospective study involved a total community population of 21,986 children, 6988 of whom experienced an influenza-like illness (ILI) between 1 November 2008 and 30 April 2009. An electronic chart was completed, a nasopharyngeal swab was obtained, and information was recorded concerning the clinical outcomes and household impact of the ILI episodes. Influenza A and B viruses were detected in all the swabs by means of polymerase chain reaction, and costs of the disease were calculated.

RESULTS

Influenza viruses were detected in 2143 cases (30.7%), an incidence of 96.4 per 1000 children. Influenza A and B viruses were found in respectively 1751 (81.7%) and 392 cases (18.3%). The mean cost of influenza was no less than €130, 32% higher than the cost of influenza-negative ILIs (p < 0.001). The influenza A cases were significantly more expensive than the influenza B cases (p < 0.001), and influenza in children aged <2 and 2-5 years was significantly more expensive than in children aged >5 years (p < 0.05). The differences were mainly related to the indirect costs of the parents' lost working days.

CONCLUSIONS

The findings of this study confirm that influenza among healthy children is important because of its frequency and its indirect consequences on the households of infected children, and support the use of influenza vaccination in healthy children aged between 6 months and 5 years.

Collection by trained pediatricians or parents of mid-turbinate nasal flocked swabs for the detection of influenza viruses in childhood

This study evaluated the efficiency of pediatric mid-turbinate nasal flocked swabs used by parents in 203 children aged 6 months to 5 years with signs and symptoms of respiratory disease. Two nasal samples were collected from each child in a randomised sequence: one by a trained pediatrician and one by a parent. The real-time polymerase chain reaction influenza virus detection rates were similar in the samples collected using the two methods (Cohen's kappa = 0.86), as were the cycle threshold values. In comparison with the pediatrician-collected samples, the sensitivity and specificity of the parental collections were respectively 89.3% (95% confidence interval [CI]: 77.8-100%) and 97.7% (95% CI: 95.5-100%), and the positive and negative predictive values were respectively 86.2% (95% CI: 73.7-95.1%) and 98.2% (95% CI: 96.4-100%). The children were significantly more satisfied with the parental collections (median values ± standard deviation, 1.59 ± 0.55 vs 3.51 ± 0.36; p < 0.0001). These findings show that mid-turbinate nasal flocked swabs specifically designed for infants and children can be used by parents without reducing the influenza virus detection rate. Moreover, the direct involvement of parents significantly increases patient acceptance, thus simplifying collection and suggesting that this novel swab design should be considered for epidemiological surveys and vaccine efficacy studies.