Diagnostic assays for respiratory syncytial virus disease

Advancing birth cohort studies using administrative and other research-independent data repositories: Opportunities and challenges

The birth cohort study design is an essential epidemiologic tool for investigating the developmental origins of health and disease. Birth cohorts have greatly improved the etiologic understanding of asthma and allergic diseases, setting the stage for advancements in translational interventions. Increasingly, investigators leverage data repositories that have been compiled and maintained independently of research investigations (administrative data) to establish large birth cohorts or to augment data generated through active participant interaction. In many cases, administrative data can greatly enhance the capacity of birth cohorts to achieve their scientific goals. However, investigators must be wary of common pitfalls and carefully consider whether administrative data are well suited to the scientific inquiry. This article reviews the strengths and challenges of using administrative data and the pragmatic solutions that have been developed to optimize their use in birth cohorts. As birth cohorts continue to play an important role in understanding the etiology of early-life disease, unleashing the power of administrative data will greatly assist in this scientific process.

Multiplex molecular assays for the laboratory-based and point-of-care diagnosis of infections caused by seasonal influenza, COVID-19, and RSV

INTRODUCTION

SARS-CoV-2, seasonal influenza, and respiratory syncytial virus (RSV) are major causes of acute respiratory infections in all age groups and responsible for an enormous socio-economic burden. The recently coined term 'tripledemic' describes co-circulation of these three viruses, a novel epidemiological paradigm that poses profound public health implications.

AREAS COVERED

Real-time reverse transcription polymerase chain reaction (RT-PCR) is now considered the reference method for the diagnosis of SARS-CoV-2, influenza, and RSV infections. Syndromic-based multiplex RT-PCR panels that simultaneously detect several respiratory viruses have become increasingly common. This review explores available molecular diagnostics (MDx) platforms for the diagnosis of SARS-CoV-2, influenza, and RSV in the same biological sample. Within some limitations of the published validation and diagnostic accuracy studies, both laboratory-based and point-of-care multiplex panels proved highly performant in identifying SARS-CoV-2, influenza A, influenza B, and RSV. Improved operational efficiency and faster turnaround times make these assays potentially cost-effective or even cost-saving.

EXPERT OPINION

The adoption of multiplex MDx assays for the contemporary detection of SARS-CoV-2, influenza, RSV, and other respiratory pathogens will likely increase in the next few years. To maximize the clinical usefulness and cost-effectiveness of these assays, locally issued guidelines and protocols on their implementation should be adopted.

RT-RPA-PfAgo detection platform for one-tube simultaneous typing diagnosis of human respiratory syncytial virus

Human respiratory syncytial virus (HRSV) is the most prevalent pathogen contributing to acute respiratory tract infections (ARTI) in infants and young children and can lead to significant financial and medical costs. Here, we developed a simultaneous, dual-gene and ultrasensitive detection system for typing HRSV within 60 minutes that needs only minimum laboratory support. Briefly, multiplex integrating reverse transcription-recombinase polymerase amplification (RT-RPA) was performed with viral RNA extracted from nasopharyngeal swabs as a template for the amplification of the specific regions of subtypes A (HRSVA) and B (HRSVB) of HRSV. Next, the Pyrococcus furiosus Argonaute (PfAgo) protein utilizes small 5'-phosphorylated DNA guides to cleave target sequences and produce fluorophore signals (FAM and ROX). Compared with the traditional gold standard (RT-qPCR) and direct immunofluorescence assay (DFA), this method has the additional advantages of easy operation, efficiency and sensitivity, with a limit of detection (LOD) of 1 copy/μL. In terms of clinical sample validation, the diagnostic accuracy of the method for determining the HRSVA and HRSVB infection was greater than 95%. This technique provides a reliable point-of-care (POC) testing for the diagnosis of HRSV-induced ARTI in children and for outbreak management, especially in resource-limited settings.

Diagnostic value of routine blood tests in differentiating between SARS-CoV-2, influenza A, and RSV infections in hospitalized children: a retrospective study

BACKGROUND

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), influenza A, and respiratory syncytial virus (RSV) infections have similar modes of transmission and clinical symptoms. There is a need to identify simple diagnostic indicators to distinguish these three infections, particularly for community hospitals and low- and middle-income countries that lack nucleic acid detection kits. This study used clinical data to assess the diagnostic value of routine blood tests in differentiating between SARS-CoV-2, influenza A, and RSV infections in children.

METHODS

A total of 1420 children treated at the Hangzhou Children's Hospital between December 2022 and June 2023 were enrolled in this study, of whom 351 had SARS-CoV-2, 671 had influenza, and 398 had RSV. In addition, 243 healthy children were also collected. The blood test results of SARS-CoV-2 patients were compared to those of patients with influenza A and RSV and the healthy controls. The area under the receiver operating characteristic curve (AUC-ROC) was employed to evaluate each blood parameter's diagnostic value.

RESULTS

Children with SARS-CoV-2 exhibited notably elevated levels of white blood cell (WBC) count, platelet (PLT) count, neutrophil count, and neutrophil-to-lymphocyte ratio (NLR) compared to influenza A patients (P < 0.05). In contrast, SARS-CoV-2 patients exhibited a decrease in the mean platelet volume to platelet count ratio (MPV/PLT) and the lymphocyte-to-monocyte ratio (LMR) when compared to other individuals (P < 0.05). These parameters had an AUC between 0.5 and 0.7. Compared to patients with RSV, SARS-CoV-2 patients had significantly higher MPV/PLT and significantly lower WBC, lymphocyte, PLT, LMR, and lymphocyte multiplied by platelet (LYM*PLT) values (P < 0.05). However, only LYM*PLT had an acceptable diagnostic value above 0.7 for all age groups. Compared to healthy children, children with COVID-19 exhibited elevated NLR and MPV/PLT levels, alongside decreased lymphocyte, PLT, LMR, and LYM*PLT values. (P < 0.05). The AUC of the LMR, LYM*PLT, and PLT were above 0.7 in all age groups, indicating promising diagnostic values.

CONCLUSIONS

The routine blood parameters among patients with COVID-19, influenza A, and RSV differ significantly early in the disease and could be used by clinicians to discriminate between the 3 types of infection.

Novel Approach for Detecting Respiratory Syncytial Virus in Pediatric Patients Using Machine Learning Models Based on Patient-Reported Symptoms: Model Development and Validation Study

BACKGROUND

Respiratory syncytial virus (RSV) affects children, causing serious infections, particularly in high-risk groups. Given the seasonality of RSV and the importance of rapid isolation of infected individuals, there is an urgent need for more efficient diagnostic methods to expedite this process.

OBJECTIVE

This study aimed to investigate the performance of a machine learning model that leverages the temporal diversity of symptom onset for detecting RSV infections and elucidate its discriminatory ability.

METHODS

The study was conducted in pediatric and emergency outpatient settings in Japan. We developed a detection model that remotely confirms RSV infection based on patient-reported symptom information obtained using a structured electronic template incorporating the differential points of skilled pediatricians. An extreme gradient boosting-based machine learning model was developed using the data of 4174 patients aged ≤24 months who underwent RSV rapid antigen testing. These patients visited either the pediatric or emergency department of Yokohama City Municipal Hospital between January 1, 2009, and December 31, 2015. The primary outcome was the diagnostic accuracy of the machine learning model for RSV infection, as determined by rapid antigen testing, measured using the area under the receiver operating characteristic curve. The clinical efficacy was evaluated by calculating the discriminative performance based on the number of days elapsed since the onset of the first symptom and exclusion rates based on thresholds of reasonable sensitivity and specificity.

RESULTS

Our model demonstrated an area under the receiver operating characteristic curve of 0.811 (95% CI 0.784-0.833) with good calibration and 0.746 (95% CI 0.694-0.794) for patients within 3 days of onset. It accurately captured the temporal evolution of symptoms; based on adjusted thresholds equivalent to those of a rapid antigen test, our model predicted that 6.9% (95% CI 5.4%-8.5%) of patients in the entire cohort would be positive and 68.7% (95% CI 65.4%-71.9%) would be negative. Our model could eliminate the need for additional testing in approximately three-quarters of all patients.

CONCLUSIONS

Our model may facilitate the immediate detection of RSV infection in outpatient settings and, potentially, in home environments. This approach could streamline the diagnostic process, reduce discomfort caused by invasive tests in children, and allow rapid implementation of appropriate treatments and isolation at home. The findings underscore the potential of machine learning in augmenting clinical decision-making in the early detection of RSV infection.

American Society of Transplantation and Cellular Therapy Series: #7 - Management of Respiratory Syncytial Virus Infections in Hematopoietic Cell Transplant Recipients

The Practice Guidelines Committee of the American Society of Transplantation and Cellular Therapy (ASTCT) partnered with its Transplant Infectious Disease Special Interest Group (TID-SIG) to update the 2009 compendium-style infectious disease guidelines for hematopoietic cell transplantation (HCT). A new approach was adopted to better serve clinical providers by publishing each standalone topic in the infectious disease series in a concise format of frequently asked questions (FAQ), tables, and figures. Experts in HCT and infectious diseases identified FAQs and then provided answers based on the strength of the recommendation and the level of supporting evidence. In the seventh guideline in the series, we focus on the respiratory syncytial virus (RSV) with FAQs addressing epidemiology, clinical diagnosis, prophylaxis, and treatment. Special consideration was given to RSV in pediatric, cord blood, haploidentical, and T cell-depleted HCT and chimeric antigen receptor T cell therapy recipients, as well as to identify future research directions.

Pediatric Respiratory Syncytial Virus Diagnostic Testing Performance: A Systematic Review and Meta-analysis

BACKGROUND

Adding additional specimen types (eg, serology or sputum) to nasopharyngeal swab (NPS) reverse transcription polymerase chain reaction (RT-PCR) increases respiratory syncytial virus (RSV) detection among adults. We assessed if a similar increase occurs in children and quantified underascertainment associated with diagnostic testing.

METHODS

We searched databases for studies involving RSV detection in persons <18 years using ≥2 specimen types or tests. We assessed study quality using a validated checklist. We pooled detection rates by specimen and diagnostic tests and quantified performance.

RESULTS

We included 157 studies. Added testing of additional specimens to NP aspirate (NPA), NPS, and/or nasal swab (NS) RT-PCR resulted in statistically nonsignificant increases in RSV detection. Adding paired serology testing increased RSV detection by 10%, NS by 8%, oropharyngeal swabs by 5%, and NPS by 1%. Compared to RT-PCR, direct fluorescence antibody tests, viral culture, and rapid antigen tests were 87%, 76%, and 74% sensitive, respectively (pooled specificities all ≥98%). Pooled sensitivity of multiplex versus singleplex RT-PCR was 96%.

CONCLUSIONS

RT-PCR was the most sensitive pediatric RSV diagnostic test. Adding multiple specimens did not substantially increase RSV detection, but even small proportional increases could result in meaningful changes in burden estimates. The synergistic effect of adding multiple specimens should be evaluated.

Underascertainment of Respiratory Syncytial Virus Infection in Adults Due to Diagnostic Testing Limitations: A Systematic Literature Review and Meta-analysis

BACKGROUND

Most observational population-based studies identify respiratory syncytial virus (RSV) by nasal/nasopharyngeal swab reverse transcriptase real-time PCR (RT-PCR) only. We conducted a systematic review and meta-analyses to quantify specimen and diagnostic testing-based underascertainment of adult RSV infection.

METHODS

EMBASE, PubMed, and Web of Science were searched (January 2000-December 2021) for studies including adults using/comparing >1 RSV testing approach. We quantified test performance and RSV detection increase associated with using multiple specimen types.

RESULTS

Among 8066 references identified, 154 met inclusion. Compared to RT-PCR, other methods were less sensitive: rapid antigen detection test (RADT; pooled sensitivity, 64%), direct fluorescent antibody (DFA; 83%), and viral culture (86%). Compared to singleplex PCR, multiplex PCR's sensitivity was lower (93%). Compared to nasal/nasopharyngeal swab RT-PCR alone, adding another specimen type increased detection: sputum RT-PCR, 52%; 4-fold rise in paired serology, 44%; and oropharyngeal swab RT-PCR, 28%. Sensitivity was lower in estimates limited to only adults (for RADT, DFA, and viral culture), and detection rate increases were largely comparable.

CONCLUSIONS

RT-PCR, particularly singleplex testing, is the most sensitive RSV diagnostic test in adults. Adding additional specimen types to nasopharyngeal swab RT-PCR testing increased RSV detection. Synergistic effects of using ≥3 specimen types should be assessed, as this approach may improve the accuracy of adult RSV burden estimates.

Respiratory Syncytial Virus-An Update for Prenatal and Primary Health Providers

Respiratory syncytial virus (RSV) infection is a significant cause of morbidity and mortality among infants aged younger than 1 year, adults aged 65 years or older, and immunocompromised persons. Limited data exist on RSV infection in pregnancy and further research is needed. Strides are being made to develop vaccines, including vaccines for maternal immunization, as well as monoclonal antibodies for disease prevention.

Respiratory Syncytial Virus is the Most Common Causative Agent of Viral Bronchiolitis in Young Children: An Updated Review

BACKGROUND

Viral bronchiolitis is a common condition and a leading cause of hospitalization in young children.

OBJECTIVE

This article provides readers with an update on the evaluation, diagnosis, and treatment of viral bronchiolitis, primarily due to RSV.

METHODS

A PubMed search was conducted in December 2021 in Clinical Queries using the key terms "acute bronchiolitis" OR "respiratory syncytial virus infection". The search included clinical trials, randomized controlled trials, case control studies, cohort studies, meta-analyses, observational studies, clinical guidelines, case reports, case series, and reviews. The search was restricted to children and English literature. The information retrieved from the above search was used in the compilation of this article.

RESULTS

Respiratory syncytial virus (RSV) is the most common viral bronchiolitis in young children. Other viruses such as human rhinovirus and coronavirus could be etiological agents. Diagnosis is based on clinical manifestation. Viral testing is useful only for cohort and quarantine purposes. Cochrane evidence-based reviews have been performed on most treatment modalities for RSV and viral bronchiolitis. Treatment for viral bronchiolitis is mainly symptomatic support. Beta-agonists are frequently used despite the lack of evidence that they reduce hospital admissions or length of stay. Nebulized racemic epinephrine, hypertonic saline and corticosteroids are generally not effective. Passive immunoprophylaxis with a monoclonal antibody against RSV, when given intramuscularly and monthly during winter, is effective in preventing severe RSV bronchiolitis in high-risk children who are born prematurely and in children under 2 years with chronic lung disease or hemodynamically significant congenital heart disease. Vaccines for RSV bronchiolitis are being developed. Children with viral bronchiolitis in early life are at increased risk of developing asthma later in childhood.

CONCLUSION

Viral bronchiolitis is common. No current pharmacologic treatment or novel therapy has been proven to improve outcomes compared to supportive treatment. Viral bronchiolitis in early life predisposes asthma development later in childhood.

Evaluation of the ImmuView RSV Test for Rapid Detection of Respiratory Syncytial Virus in Adult Patients with Influenza-Like Symptoms

Rapid antigen tests may enhance the diagnostic yield of respiratory syncytial virus (RSV) infections, but studies have shown low sensitivity in adults. We evaluated the novel ImmuView RSV test in adult patients with influenza-like symptoms who were prospectively enrolled at three emergency departments in two Swedish hospitals during two influenza seasons, 2017 to 2018 and 2018 to 2019. The ImmuView RSV test was performed on nasopharyngeal swabs and results were compared to those of the BinaxNOW RSV test. In the first season, tests were performed on frozen samples, while unfrozen samples were used in the second season. For comparison, tests were also performed on selected samples from children. Of 333 included adult patients, the sensitivity of ImmuView and BinaxNOW was 27% for both tests and specificities were 98% and 100%, respectively. The interassay agreement was good (κ = 0.61). There was no significant difference in test performance between frozen and unfrozen samples. In samples from children, the sensitivities of ImmuView and BinaxNOW were 67% and 70%, respectively. In conclusion, the ImmuView RSV test showed low sensitivity and high specificity for identifying RSV in adult patients with influenza-like symptoms, comparable with the BinaxNOW RSV test. Rapid RSV testing is of limited value for diagnosing RSV infection in adults. IMPORTANCE By timely RSV diagnosis among patients with influenza-like symptoms, especially when influenza diagnostics turn negative, it is possible to prevent unnecessary antibiotic usage as well as reduce diagnostic testing, nosocomial transmission, and hospital stay. Previous rapid RSV tests have demonstrated poor sensitivity in adults, and we could demonstrate that the novel ImmuView RSV test similarly showed limited value for diagnosing RSV infection in adult patients. However, in contrast to many other studies, we investigated patient characteristics in cases with false-positive tests and we compared the performance between unfrozen and frozen samples. Thus, our results are important, as they generate new knowledge about rapid antigen tests.

The spatial-temporal dynamics of respiratory syncytial virus infections across the east-west coasts of Australia during 2016-17

Respiratory syncytial virus (RSV) is an important human respiratory pathogen. In temperate regions, a distinct seasonality is observed, where peaks of infections typically occur in early winter, often preceding the annual influenza season. Infections are associated with high rates of morbidity and mortality and in some populations exceed that of influenza. Two subtypes, RSV-A and RSV-B, have been described, and molecular epidemiological studies have shown that both viruses mostly co-circulate. This trend also appears to be the case for Australia; however, previous genomic studies have been limited to cases from one Eastern state—New South Wales. As such, the broader spatial patterns and viral traffic networks across the continent are not known. Here, we conducted a whole-genome study of RSV comparing strains across eastern and Western Australia during the period January 2016 to June 2017. In total, 96 new RSV genomes were sequenced, compiled with previously generated data, and examined using a phylodynamic approach. This analysis revealed that both RSV-A and RSV-B strains were circulating, and each subtype was dominated by a single genotype, RSV-A ON1-like and RSV-B BA10-like viruses. Some geographical clustering was evident in strains from both states with multiple distinct sub-lineages observed and relatively low mixing across jurisdictions, suggesting that endemic transmission was likely seeded from imported, unsampled locations. Overall, the RSV phylogenies reflected a complex pattern of interactions across multiple epidemiological scales from fluid virus traffic across global and regional networks to fine-scale local transmission events.

Convolutional neural network analysis of recurrence plots for high resolution melting classification

BACKGROUND AND OBJECTIVE

High resolution melting (HRM) analysis is a rapid and correct method for identification of species, such as, microorganism, bacteria, yeast, virus, etc. HRM data are produced using real-time polymerase chain reaction (PCR) and unique for each species. Analysis of the HRM data is important for several applications, such as, for detection of diseases (e.g., influenza, zika virus, SARS-Cov-2 and Covid-19 diseases) in health, for identification of spoiled foods in food industry, for analysis of crime scene evidence in forensic investigation, etc. However, the characteristics of the HRM data can change due to the experimental conditions or instrumental settings. In addition, it becomes laborious and time-consuming process as the number of samples increases. Because of these reasons, the analysis and classification of the HRM data become challenging for species which have similar characteristics.

METHODS

To improve the classification accuracy of HRM data, we propose to use image (visual) representation of HRM data, which we call HRM images, that are generated using recurrence plots, and propose convolutional neural network (CNN) based models for classifying HRM images. In this study, two different types of recurrence plots are generated, which are black-white recurrence plots (BW-RP) and gray scale recurrence plots (GS-RP) and four different CNN models are proposed for classifying HRM data.

RESULTS

The classification performance of the proposed methods are evaluated based on average classification accuracy and F1 score, specificity, recall, and precision values for each yeast species. When BW-RP representation of HRM data is used as input to the CNN models, the best classification accuracy of 95.2% is obtained. The classification accuracies of CNN models for melting curve and GS-RP data representations of HRM data are 90.13% and 86.13%, respectively. The classification accuracy of support vector machines (SVM) model that take melting curve representation of HRM data is 86.53%. Moreover, when BW-RP representation of HRM data is used as input to the CNN models, the F1 score, specificity, recall and precision values are the highest for almost all of species.

CONCLUSIONS

Experimental results show that using BW-RP representation of HRM data improved the classification accuracy of HRM data and CNN models that take these images as input outperformed CNN models that take melting curve and GS-RP representations of HRM data as inputs and SVM model that take melting curve representation of HRM data as input.

A novel point-of-care test of respiratory syncytial viral RNA based on cellulose-based purification and convective PCR

BACKGROUND

Respiratory syncytial virus (RSV) infection is a global public-health problem. Timely diagnostics are needed for high-risk patients. Several methods have been used for RSV detection but not suitable for on-site detection due to the requirement of specialized laboratories and expensive equipment.

METHODS

We developed a convenient, rapid and low-cost method of nucleic acids (NA) extraction based on cellulose paper, which could extract NA from nasopharyngeal swabs (NPSs) within 1 min. This extraction method was integrated with fluorescence convection polymerase chain reaction (CPCR), which easily affordable and easy-to-use NA detection of the RSV in 33 min.

RESULTS

The developed cellulose-based NA purification combine with CPCR (CP-CPCR) reliably detected as little as 0.01 TCID₅₀/mL of RSV cultures. CP-CPCR performance was tested further using NPSs: it showed sensitivity of 100% and a specificity of 100% compared with traditional extraction and amplification methods.

CONCLUSIONS

Our evaluation confirmed high specificity, sensitivity and efficient of the CP-CPCR, which can be used widely for RSV testing in resource-limited settings.

Accuracy of diagnostic tests for respiratory syncytial virus infection within a paediatric hospital population in Kilifi County, Kenya

Background: Respiratory syncytial virus (RSV)-induced lower respiratory tract disease is a prominent cause of hospitalisation among children aged <5 years in developing countries. Accurate and rapid diagnostic tests are central to informing effective patient management and surveillance efforts geared towards quantifying RSV disease burden. This study sought to estimate the sensitivity (Se), specificity (Sp) (along with the associated factors) and predictive values of a direct immunofluorescence test (IFAT), and two real-time reverse transcription polymerase chain reaction (rRT-PCR) assays for RSV infection within a paediatric hospital population: a multiplex rRT-PCR (MPX) and Fast-Track Diagnostics ® (FTD) Respiratory Pathogens 33 (Resp-33) rRT-PCR. Methods: The study enlisted 1458 paediatrics aged ≤59 months admitted with acute respiratory illness at the Kilifi County Hospital between August 2011 and December 2013. A Bayesian latent class modelling framework was employed to infer the tests' estimates based on the patients' diagnostic data from the three tests. Results: The tests posted statistically similar Se estimates: IFAT (93.7%, [90.7; 95.0]), FTD (97.8%, [94.6; 99.4]) and MPX (97.5%, [94.2; 99.3]). As for Sp, FTD registered a lower estimate (97.4%, [96.2; 98.2]) than MPX (99.7%, [99.0; 100.0]) but similar to IFAT (99.0%, [98.2; 99.6]). The negative and positive predictive values were strong (>91%) and closely mimicked the pattern given by the Se and Sp values respectively. None of the examined covariates (age, sex and pneumonia status) significantly influenced the accuracy of the tests. Conclusions: The evaluation found little to choose between the three diagnostic tests. Nonetheless, with its relative affordability, the conventional IFAT continues to hold promise for use in patient care and surveillance activities for RSV infection within settings where children are hospitalised with severe acute respiratory illness.

Outcomes of patients with Severe Acute Respiratory Infections (SARI) admitted to the intensive care unit: results from the Egyptian Surveillance Study 2010-2014

Background

Few data exist about respiratory viral infections in Egyptian patients. Hereby we describe the outcomes of hospitalized Egyptian patients with severe acute respiratory infections (SARI) admitted to the ICU.

Methods

A prospective study in which all hospitalized patients meeting the WHO case definition for SARI and admitted to the ICU, during the period 2010–2014, were enrolled. Samples were tested using RT-PCR for influenza A, B, respiratory syncytial virus (RSV), human metapneumovirus (hMPV), parainfluenza virus, adenovirus, bocavirus, enterovirus, and rhinovirus. Data were analyzed to study the clinical features of SARI-ICU patients and which pathogens are related to severe outcomes. Associated comorbidities were evaluated using Charlson Age-Comorbidity Index (CACI).

Results

Out of 1,075 patients with SARI, 219 (20.3%) were admitted to the ICU. The highest rates were reported for RSV (37%). SARI-ICU patients had higher rates of hospital stay, pneumonia, respiratory failure, ARDS, and mortality. Multivariate logistic regression analysis identified associated respiratory disorders (p=0.001), radiological abnormalities (p=0.023), and longer hospital stay (p=0.005) as risk factors for severe outcomes.

Conclusions

This surveillance study showed that 20% of hospitalized Egyptian patients with viral SARI needed ICU admission. SARI-ICU patients had higher rates of hospital stay, pneumonia, respiratory failure, ARDS, and mortality. Higher comorbidity index scores, radiological abnormalities, and longer hospital stay are risk factors for severe outcomes in SARI-ICU patients in our locality.

Six-monthly palivizumab prophylaxis effectively reduced RSV-associated hospitalization rates of preterm infants in a subtropical area: a population-based cohort study

BACKGROUND

To evaluate the effects of 6-monthly palivizumab on respiratory syncytial virus-associated hospitalization (RSVH) in preterm infants in an area without RSV seasonality.

METHODS

RSV prophylaxis with 6-monthly palivizumab in infants born at gestational age (GA) ≤28 weeks or those born at GA 29-35 weeks with bronchopulmonary dysplasia (BPD) was implemented in Taiwan since 2010. RSVH, use of mechanical ventilation (MV), admission to intensive care unit (ICU), length of hospital stay, and annual mortality were compared between the historical control group (no prophylaxis, 2008-2009) and the prophylaxis group (2011-2013).

RESULTS

The annual RSVH rates decreased in the target population and in subgroups of infants who received prophylaxis (all target infants: odds ratio [OR], 0.43; 95% confidence interval [CI], 0.29-0.65). No difference was observed in MV and ICU usage and 1-year mortality in the ≤28 weeks subgroup. In the GA 29-35 weeks with BPD subgroup, ICU usage and 1-year mortality rates were significantly reduced with palivizumab prophylaxis regimen. A significant decrease was noted in the annual mortality and ICU admission rates of infants who received prophylactic treatment.

CONCLUSION

Six-monthly palivizumab treatment reduced the RSVH rate, ICU usage, and annual mortality rates of target infants in an area without RSV seasonality.

Viral Surveillance of Children with Acute Respiratory Infection in Two Main Hospitals in Northern Jordan, Irbid, during Winter of 2016

Acute lower respiratory infection (ALRI) is a major cause of morbidity and mortality worldwide. Data regarding the etiology of acute respiratory infection (ARI) is scarce in developing countries. The aim of this study was to identify the viral etiology of ARI/ALRI in hospitalized children and factors associated with increased length of stay (LoS) and severe disease presentation in Northern Jordan. This was a prospective viral surveillance study using real-time reverse transcriptase-polymerase chain reaction in children younger than 5 years admitted with ARI to two main hospitals in Northern Jordan during the winter of 2016. Nasopharyngeal swabs were obtained and tested for respiratory syncytial virus (RSV) and other viruses. Demographic and clinical characteristics of RSV-positive patients were compared with those of RSV-negative patients. There were 479 patients hospitalized with ARI. Their mean age (standard deviation) was 10.4 (11.6) months. 53.9% tested positive for at least one virus, with RSV being the most commonly detected virus (34%). Compared with RSV-negative patients, RSV-positive patients were younger, more likely to have chronic lung disease, and more likely to present with cough, rhinorrhea, difficulty in breathing, retraction, flaring, grunting, wheezing, and a higher respiratory rate. Prematurity, presence of a chronic illness, oxygen saturation < 90%, and atelectasis and consolidation on chest X-rays were significantly associated with an increased mean LoS. Patients with a history of prematurity had higher risk of severe disease (odds ratio = 2.6; 95% confidence interval: 1.5, 4.7; p  = 0.001). Compared with patients 6 months old and younger, patients aged 6.1 to 12 months were less likely to have severe disease. Human metapneumovirus (HMPV)-positive ALRI was associated with increased odds of severe disease. Viruses are recognized as etiological agent of ARI/ALRI-associated morbidity in developing countries that need more attention and implementation of targeted strategies for prevention and detection. HMPV can be a cause of severe ALRI.

Laboratory Evaluation of Rapid Antigen Detection Tests for More-Sensitive Detection of Respiratory Syncytial Virus Antigen

We evaluated two currently available rapid antigen detection tests (RADTs) for Respiratory syncytial virus (RSV), Sofia^® RSV FIA and BinaxNOW RSV Card (BinaxNOW). Between November 2017 and February 2018, 395 nasopharyngeal swabs were collected from children diagnosed with acute respiratory infections. The swabs were evaluated using the aforementioned RADTs, the reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR), and the direct immunofluorescence assay (DFA). The sensitivity of Sofia^® RSV FIA (80.82%) was significantly higher than that of BinaxNOW (53.42%) when RT-qPCR was used as the standard. This was confirmed with DFA. The sensitivities of Sofia^® RSV FIA (85.4% [41/48]) and BinaxNOW (58.3% [28/48]) were higher for RSV A than for RSV B (69.6% [16/23] and 43.5% [10/23], respectively). The optimal critical cycle threshold (Ct) values on RT-qPCR that correlated with Sofia^® RSV FIA and BinaxNOW were 24 and 22, respectively. The kappa value for Sofia^® RSV FIA and RT-qPCR was 0.962 in patients who were two years old or younger, but 0.648 in those who were more than two years old. Thus, Sofia^® RSV FIA is more sensitive than BinaxNOW; its results were affected by the RSV viral strain and load. Sofia^® RSV FIA is more effective in children who are ≤ 2 years old than in those who are > 2 years old.

Clinical characteristics and outcomes of patients with severe acute respiratory infections (SARI): results from the Egyptian surveillance study 2010-2014

Background

Respiratory viral and atypical bacterial infections data in Egyptian patients are sparse. This study describes the clinical features and outcomes of patients with severe acute respiratory infections (SARI) in hospitalized patients in Egypt.

Methods

SARI surveillance was implemented at Cairo University Hospital (CUH) during the period 2010–2014. All hospitalized patients meeting the WHO case definition for SARI were enrolled. Nasopharyngeal/oropharyngeal (NP/OP) swabs were collected and samples were tested using RT-PCR for influenza A, B, respiratory syncytial virus (RSV), human metapneumovirus (hMPV), parainfluenza virus (PIV 1,2,3,4), adenovirus, bocavirus, coronavirus, enterovirus, rhinovirus, and atypical bacteria. Data were analyzed to calculate positivity rates for viral pathogens and determine which pathogens related to severe outcomes or resulted in death.

Results

Overall, 1,075/3,207 (33.5%) cases had a viral etiology, with a mean age of 5.74 (±13.87) years. The highest rates were reported for RSV (485 cases, 45.2%), PIV (125, 11.6%), and adenovirus (105, 9.8%). Children had a higher viral rate (981, 91.2%) compared to 94 (8.8%) cases in adults. Patients with identified viruses had significantly lower rates for ICU admission, hospital stay, mechanical ventilation, and overall mortality than those without identified viruses. No infections were independently associated with severe outcomes.

Conclusions

Viral pathogens were encountered in one-third of hospitalized adult and pediatric Egyptian patients with SARI, while atypical bacteria had a minor role. Highest rates of viral infections were reported for RSV, PIV, and adenovirus. Viral infections had neither negative impacts on clinical features nor outcomes of patients with SARI in our locality.

Evaluation of the national laboratory-based surveillance system for respiratory syncytial virus in Sweden, 2015-2016

BACKGROUND

Most laboratories use RSV PCR but near-patient tests (NPT) performed at paediatric clinics are believed to be increasingly used. Anonymised data on RSV infections has been collected since 1990 in Sweden. No evaluation of Swedish RSV surveillance or use of laboratory testing had previously been performed.

OBJECTIVES

Swedish RSV data and methods used for RSV laboratory testing and reporting were evaluated in order to improve RSV surveillance in a forthcoming vaccine era.

STUDY DESIGN

RSV data obtained in Sweden 2015-2016 were reviewed. Data on methods used for the RSV laboratory detection and reporting were collected via on-line questionnaires submitted to laboratories (n = 26) and clinics (n = 4) known to perform virological testing. Swedish Quality Control Program reports from 2013 to 2015 on the performance of RSV testing were also evaluated.

RESULTS

Over 60% of RSV infections were diagnosed in children under 5 years (1917/2925), but infections were also common in those 65 years and older (n = 607). Two laboratories limited RSV testing to children only. RSV NPT was utilised in eight clinics; four participated in RSV surveillance. RSV NPTs evaluated could only detect 50% of RSV positive samples. Reporting was complete and timely, but took too much time (18 min/week/laboratory).

CONCLUSIONS

Although most common in children, RSV infections are also common in the elderly, and testing should not be limited to children only. The poor performance of RSV NPT and importance of confirming results should be communicated to all relevant laboratories and clinics. All clinics should be encouraged to participate in surveillance. Automated case-based reporting should be considered.

Determining the Seasonality of Respiratory Syncytial Virus in the United States: The Impact of Increased Molecular Testing

Background

In the United States, the seasonality of respiratory syncytial virus (RSV) has traditionally been defined on the basis of weeks during which antigen-based tests detect RSV in >10% of specimens (hereafter, the "10% threshold"). Because molecular testing has become more widely used, we explored the extent of polymerase chain reaction (PCR)-based RSV testing and its impact on determining the seasonality of RSV.

Methods

We assessed antigen- and PCR-based RSV reports submitted to the National Respiratory and Enteric Virus Surveillance System during July 2005-June 2015. To characterize RSV seasons by using PCR-based reports, we assessed the traditional 10% threshold; subsequently, we developed 3 methods based on either PCR-based detections or the percentage of positive test results.

Results

The annual number of PCR-based reports increased 200-fold during 2005-2015, while the annual number of antigen-based reports declined. The weekly percentage of specimens positive for RSV by PCR was less than that for antigen-detection tests; accordingly, the 10% threshold excluded detections by PCR and so was imprecise for characterizing RSV seasons. Among our PCR-specific approaches, the most sensitive and consistent method captured 96%-98% of annual detections within a season, compared with 82%-94% captured using the traditional method.

Conclusions

PCR-based reports are increasingly relevant for RSV surveillance and determining the seasonality of RSV. These PCR-specific methods provide a more comprehensive understanding of RSV trends, particularly in settings where testing and reporting are most active. Diagnostic practices will vary by locality and should be understood before choosing which method to apply.

Viral etiology, seasonality and severity of hospitalized patients with severe acute respiratory infections in the Eastern Mediterranean Region, 2007-2014

Introduction

Little is known about the role of viral respiratory pathogens in the etiology, seasonality or severity of severe acute respiratory infections (SARI) in the Eastern Mediterranean Region.

Methods

Sentinel surveillance for SARI was conducted from December 2007 through February 2014 at 20 hospitals in Egypt, Jordan, Oman, Qatar and Yemen. Nasopharyngeal and oropharyngeal swabs were collected from hospitalized patients meeting SARI case definitions and were analyzed for infection with influenza, respiratory syncytial virus (RSV), adenovirus (AdV), human metapneumovirus (hMPV) and human parainfluenza virus types 1–3 (hPIV1-3). We analyzed surveillance data to calculate positivity rates for viral respiratory pathogens, describe the seasonality of those pathogens and determine which pathogens were responsible for more severe outcomes requiring ventilation and/or intensive care and/or resulting in death.

Results

At least one viral respiratory pathogen was detected in 8,753/28,508 (30.7%) samples tested for at least one pathogen and 3,497/9,315 (37.5%) of samples tested for all pathogens–influenza in 3,345/28,438 (11.8%), RSV in 3,942/24,503 (16.1%), AdV in 923/9,402 (9.8%), hMPV in 617/9,384 (6.6%), hPIV1 in 159/9,402 (1.7%), hPIV2 in 85/9,402 (0.9%) and hPIV3 in 365/9,402 (3.9%). Multiple pathogens were identified in 501/9,316 (5.4%) participants tested for all pathogens. Monthly variation, indicating seasonal differences in levels of infection, was observed for all pathogens. Participants with hMPV infections and participants less than five years of age were significantly less likely than participants not infected with hMPV and those older than five years of age, respectively, to experience a severe outcome, while participants with a pre-existing chronic disease were at increased risk of a severe outcome, compared to those with no reported pre-existing chronic disease.

Conclusions

Viral respiratory pathogens are common among SARI patients in the Eastern Mediterranean Region. Ongoing surveillance is important to monitor changes in the etiology, seasonality and severity of pathogens of interest.

Impact of a Transition from Respiratory Virus Shell Vial to Multiplex PCR on Clinical Outcomes and Cost in Hospitalized Children

While respiratory virus PCR panel (RVPP) is more expensive than shell vial (SV) cell culture, it has been shown to reduce unnecessary diagnostic procedures, decrease the inappropriate use of antimicrobials, and shorten the hospital length of stay (LOS). We therefore hypothesized that, for hospitalized children, RVPP would be associated with improved clinical outcomes but higher hospital charges than SV cell culture. We performed a retrospective cohort study of hospitalized children. Multivariate analysis was performed, and p-values were calculated. Respiratory virus testing was collected in a total of 1625 inpatient encounters, of which 156 were tested positive by RVPP (57.7%) and 112 were tested positive by SV (11.1%, p < 0.05). Excluding human rhinovirus (HRV) and human metapneumovirus (hMPV) from the analysis, patients with a positive test from SV had more comorbidities (p = 0.04) and higher mortality (p = 0.008). Patients with a positive test from RVPP had shorter LOS (p = 0.0503). Hospital charges for patients with a positive test from RVPP were lower, but not significantly so. When a multivariate analysis was performed, there were no statistically significant differences in comorbidities, mortality, LOS, or median hospital charges between those patients with a positive SV and those with a positive RVPP. Although testing with RVPP significantly increased the detection of respiratory viruses, clinical outcomes remained comparable to those tested with SV, however RVPP was found to not be associated with higher long-term hospital costs.

Performance evaluation of four rapid antigen tests for the detection of Respiratory syncytial virus

Rapid identification of Respiratory syncytial virus (RSV) is important in the management of infected patients. Rapid diagnostic tests (RDT) are widely used for this purpose. This study aimed to evaluate the clinical performance of four RSV antigen tests including the BinaxNow RSV Card test, SD Bioline RSV test, BD Veritor RSV test, and Humasis RSV antigen test in comparison with real-time RT-PCR as the reference method. Nasopharyngeal swabs were collected from 280 patients with symptoms of lower respiratory tract infection and stored at -80°C. All swabs were tested for RSV using four rapid antigen tests and real time RT-PCR. The sensitivity of the BinaxNow RSV Card test, SD Bioline RSV test, BD Veritor RSV test, and Humasis RSV Antigen tests were 62.5%, 61.3%, 65.0%, and 67.5% for RSV A, and 61.3%, 65.0%, 61.3%, and 67.5% for RSV B compared to real time RT-PCR, respectively. The specificity of BD Veritor RSV test was 95.8% and those of the other three RDTs was 100%. Commercial RSV antigen detection assays are useful tools for the rapid diagnosis of RSV infection. However, confirmatory testing is always recommended. J. Med. Virol. 88:1720-1724, 2016. © 2016 Wiley Periodicals, Inc.

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.

Comparison of Intravenous Palivizumab and Standard of Care for Treatment of Respiratory Syncytial Virus Infection in Mechanically Ventilated Pediatric Patients

OBJECTIVES

Evidence suggests palivizumab may be beneficial for respiratory syncytial virus (RSV) infection in pediatric patients, although it is only approved by the US Food and Drug Administration for RSV prophylaxis. The objective of this study is to compare outcomes among pediatric patients with RSV infection who received intravenous palivizumab and standard of care versus standard of care alone.

METHODS

This is a retrospective, single-center cohort study conducted between November 2003 and October 2013. Pediatric patients with active RSV infection treated with intravenous (IV) palivizumab after initiation of mechanical ventilation were matched 1:1 to a control selected from ventilated patients who received standard of care. The primary end point evaluated the duration of mechanical ventilation between groups. Secondary end points included hospital length of stay, intensive care unit length of stay, duration of respiratory support over baseline, time to RSV microbiologic cure, duration of antibiotic therapy, and in-hospital mortality.

RESULTS

A total of 22 patients with a median age of 3 months were included in the study. Patients in the treatment group received a median of 2 doses of IV palivizumab, with a mean dose of 14.2 mg/kg. All patients received bronchodilators and corticosteroids, with the exception of 1 patient in the control group, and only 1 treatment group patient received IV ribavirin. Duration of mechanical ventilation was longer in the treatment group (18.9 ± 9.5 vs. 14.3 ± 9.3 days; p = 0.26). No statistically significant differences were observed between groups for any of the secondary end points.

CONCLUSIONS

Pediatric patients who received IV palivizumab in addition to standard of care for treatment of RSV infection following initiation of mechanical ventilation experienced similar outcomes to those who received standard of care alone. Further studies are necessary to evaluate the potential benefit of IV palivizumab in addition to current standard of care.

Respiratory Infections

The majority of respiratory tract infections (RTIs) are community acquired and are the single most common cause of physician office visits and among the most common causes of hospitalizations. The morbidity and mortality associated with RTIs are significant and the financial and social burden high due to lost time at work and school. The scope of clinical symptoms can significantly overlap among the respiratory pathogens, and the severity of disease can vary depending on patient age, underlying disease, and immune status, thereby leading to inaccurate presumptions about disease etiology. The rapid and accurate diagnosis of the causative agent of RTIs improves patient care, reduces morbidity and mortality, promotes effective hospital bed utilization and antibiotic stewardship, and reduces length of stay. This chapter focuses on the clinical utility, advantages, and disadvantages of viral and bacterial tests cleared by the Food and Drug Administration (FDA), and new promising technologies for the detection of bacterial agents of pneumonia currently in development or in US FDA clinical trials are briefly reviewed.

Evaluation of a fluorescent immunoassay rapid test (Sofia™) for detection of influenza A+B and RSV in a tertiary pediatric setting

In response to the lack of sensitivity and reproducibility of previously marketed rapid antigen detection tests, a novel fluorescent immunoassay was recently developed. This new assay offers rapidity and automated reading. More characterization of this assay is needed. The aim of this study was to assess diagnostic performance of Sofia influenza A+B and respiratory syncytial virus (RSV) while compared to traditional viral cell culture. A total of 416 respiratory samples were analyzed prospectively with both methods in a tertiary pediatric center. Sensitivity and specificity of the Sofia™ test were 90.0% and 98.0% for influenza A, 90.9% and 98.9% for influenza B, and 87.7% and 94.7% for RSV compared to traditional cell culture. Overall, Sofia influenza A+B and RSV assays performed well in comparison to culture in a pediatric population.

Respiratory viruses and their impact in healthcare

PURPOSE OF REVIEW

As viral respiratory infections are responsible for significant morbidity and mortality, and are associated with numerous challenges for infection control, we provide an overview of the most recent publications on healthcare-associated respiratory infections.

RECENT FINDINGS

Populations most susceptible to respiratory viruses include neonates, immunocompromised and elderly populations. Newer polymerase chain reaction-based assays are more sensitive and are able to detect multiple respiratory viruses. The significance of virus detection among asymptomatic individuals, however, remains unclear. There is more evidence of airborne transmission of influenza, but currently N95 masks are recommended only for aerosol generating procedures. Transocular transmission of influenza has been demonstrated in the experimental setting, but further research is needed of transocular transmission of other respiratory viruses. Mandatory vaccination of healthcare workers against influenza has been shown to reduce influenza rates and patient mortality.

SUMMARY

Infection control measures can be supplemented with use of polymerase chain reaction testing to determine causes, but the cornerstone of prevention relies on enforcing appropriate isolation measures for patients: hand hygiene; appropriate use of personal protective equipment by healthcare workers; illness screening of visitors; and influenza vaccination of healthcare workers, patients and families.

Effect of young sibling visitation on respiratory syncytial virus activity in a NICU

OBJECTIVE

To determine whether the restriction of young sibling (<13 years) visitation in the neonatal intensive care unit (NICU) during the respiratory syncytial virus (RSV) season was associated with a reduction in the rate of RSV infection among NICU patients.

STUDY DESIGN

A retrospective chart review of all RSV positive infants from the 2001-2010 RSV seasons. The 2001-2006 RSV seasons (group 1) contained 639 admissions and the 2007-2010 (group 2, with sibling restriction) contained 461 admissions. Groups were compared by using the Fisher's Exact Test.

RESULTS

There was a reduction of RSV positive infants from 6.7% in Group 1 to 1.7% in Group 2 (P<0.0001). There was a reduction of symptomatic infants from the number of infants with symptomatic RSV infection from 23/639 infants with young sibling visitation to 2/461 (P<0.001).

CONCLUSION

Exclusion of young sibling visitors <13 years of age during RSV season was associated with a significant reduction in the number of RSV positive infants in the NICU.

Respiratory syncytial virus infection in older adults: an under-recognized problem

Human respiratory syncytial virus (RSV) is an enveloped, single-stranded, negative-sense RNA virus and member of the Paramyxoviridae family of the genus Pneumovirus that was first reported as a major pathogen in pediatric populations. However, since its discovery, RSV has not infrequently been detected in adults. Reinfection occurs throughout life, with more severe disease occurring in older adults, immunocompromised patients, and those with underlying cardiopulmonary disease. Initially described as the cause of nursing home outbreaks of respiratory disease, there is a now significant body of literature describing the clinical importance of RSV in older adults in a multitude of settings including long-term care, adult daycares, and in community-dwelling adults. Moreover, recent reports from China and other countries emphasize that RSV is a global pathogen that will become increasingly important in developed nations with aging populations. Annual attack rates in the USA range from 2 to 10% in community-dwelling older adults and 5-10% in older adults living in congregate settings. Population-based calculations of the proportion of acute respiratory illnesses attributable to RSV estimate that 11,000 elderly persons die annually in the USA of illnesses related to RSV infection. Clinical manifestations of RSV infections are similar to that of other viral respiratory pathogens and include cough, nasal congestion, rhinorrhea, sore throat, and dyspnea. Lower respiratory tract disease is common and may result in respiratory failure (8-13%) or death (2-5%). Recent advances in molecular diagnostics have made it possible to rapidly identify RSV infection using nucleic acid amplification tests, although clinicians will need to suspect the diagnosis when viral activity is high. At the present time, treatment is supportive. Effective antiviral agents for the treatment and vaccines for prevention of RSV remain a significant unmet medical need in the older adult population.

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.

Recent advances in the management of acute bronchiolitis

Acute bronchiolitis is characterized by acute wheezing in infants or children and is associated with signs or symptoms of respiratory infection; it is rarely symptomatic in adults and the most common etiologic agent is respiratory syncytial virus (RSV). Usually it does not require investigation, treatment is merely supportive and a conservative approach seems adequate in the majority of children, especially for the youngest ones (<3 months); however, clinical scoring systems have been proposed and admission in hospital should be arranged in case of severe disease or a very young age or important comorbidities. Apnea is a very important aspect of the management of young infants with bronchiolitis. This review focuses on the clinical, radiographic, and pathologic characteristics, as well as the recent advances in management of acute bronchiolitis.

Measles-mumps-rubella vaccination and respiratory syncytial virus-associated hospital contact

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MMR vaccination is given to protect against measles, mumps and rubella.

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RSV is an important cause of acute lower respiratory infections in young children.

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MMR vaccination was associated with 22% lower rate of RSV hospital contacts.

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MMR vaccination may reduce the rate or severity of RSV infection.

Background

The live measles vaccine has been associated with lower non-measles mortality and admissions in low-income countries. The live measles–mumps–rubella vaccine has also been associated with lower rate of admissions with any type of infection in Danish children; the association was strongest for admissions with lower respiratory infections.

Objective

To examine whether measles, mumps, and rubella (MMR) vaccination was associated with reduced rate of hospital contact related to respiratory syncytial virus (RSV) in a high-income country.

Methods

Nationwide cohort study of laboratory-confirmed RSV hospital contacts at age 14–23 months in all children born in Denmark 1997–2002 who had already received the vaccine against diphtheria, tetanus, pertussis (acellular), polio, and Haemophilus influenzae type b (DTaP-IPV-Hib) at the recommended ages of 3, 5, and 12 months.

Results

The study included 888 RSV hospital contacts in 128,588 person years of follow up (rate 6.8/1000 person years). Having MMR as the most recent vaccine was associated with a reduced rate of RSV hospital contacts compared with having DTaP-IPV-Hib as the most recent vaccine (Incidence rate ratio (IRR), 0.75; 95% confidence interval (CI), 0.63–0.89). After adjustment for potential confounders including exact age in days the IRR was 0.78 (95% CI, 0.66–0.93). The adjusted IRR was 0.74 (95% CI, 0.60–0.92) in males and 0.84 (95% CI, 0.66–1.06) in females (P Interaction, 0.42). There was no association in the first month after MMR vaccination (adjusted IRR, 0.97; 95% CI, 0.76–1.24) but the adjusted IRR was 0.70 (95% CI, 0.58–0.85) from one month after MMR vaccination.

Conclusions

MMR vaccination was associated with reduced rate of hospital contacts related to laboratory-confirmed RSV infection. Further research on the association between MMR vaccination and other unrelated pathogens are warranted.

Systematic review and meta-analysis of respiratory syncytial virus infection epidemiology in Latin America

Respiratory syncytial virus (RSV) is a frequent cause of acute respiratory infection and the most common cause of bronchiolitis in infants. The aim of this systematic review and meta-analysis was to obtain a comprehensive epidemiological picture of the data available on disease burden, surveillance, and use of resources in Latin America. Pooled estimates are useful for cross-country comparisons. Data from published studies reporting patients with probable or confirmed RSV infection in medical databases and gray literature were included from 74 studies selected from the 291 initially identified. When considering all countries, the largest pooled percentage RSV in low respiratory tract infection patients was found in the group between 0 and 11 months old, 41.5% (95% CI 32.0–51.4). In all countries, percentages were increasingly lower as older children were included in the analyses. The pooled percentage of RSV in LRTIs in the elderly people was 12.6 (95% CI 4.2–24.6). The percentage of RSV infection in hospitalized newborns was 40.9% (95% CI 28.28–54.34). The pooled case fatality ratio for RSV infection was 1.74% (95% CI 1.2–2.4) in the first 2 years of life. The average length of stay excluding intensive care unit admissions among children with risk factors for severe disease was 12.8 (95% CI 8.9–16.7) days, whereas it averaged 7.3 (95% CI 6.1/8.5) days in otherwise healthy children.We could conclude that infants in their first year of age were the most vulnerable population. To our knowledge, this is the first systematic review on RSV disease burden and use of health resources in Latin America.

The role of multiplex PCR in respiratory tract infections in children

BACKGROUND

Infants, toddlers, and children of primary-school age without any special risk factors generally have three to ten febrile respiratory infections per year. Most such infections are of viral origin and self-limiting, but viral infection is often hard to distinguish from bacterial infection. The use of a multiplex polymerase chain reaction (PCR) to detect viruses in respiratory secretions is potentially beneficial, as it might help physicians avoid giving antibiotics unnecessarily.

METHOD

This article is based on a selective review of the literature and on the findings of the authors' own investigations.

RESULTS

Multiplex PCR is a highly sensitive, highly specific test for the detection of viral nucleic acids in respiratory secretions. If PCR reveals the presence of RNA derived from respiratory syncytial virus, human metapneumovirus, parainfluenza virus, or influenza virus, then an acute infection caused by the corresponding pathogen is probably present, and further treatment can be given accordingly. On the other hand, the nucleic acids of adeno-, boca-, rhino- or coronaviruses can be found in relatively trivial infections as well as in asymptomatic persons, probably reflecting either a prior infection or a current subclinical one. For children in particular, upper respiratory infections are so common in the winter months that acute and prior infections with these pathogens cannot be distinguished by multiplex PCR. The use of multiplex PCR in children has not been shown to shorten hospital stays or to lessen antibiotic consumption or overall cost.

CONCLUSION

The detectability of viral nucleic acids is an important contribution to the diagnostic assessment of children with severe respiratory infection. For these highly sensitive diagnostic tests to be used optimally, primary viral infections must be distinguished from bacterial superinfections.

Recent evidence on the management of bronchiolitis

PURPOSE OF REVIEW

Bronchiolitis is a common condition in children less than 2  years of age and is a leading cause of infant hospitalization. Although there is significant variability in testing and treatment of children with bronchiolitis, diagnostic testing rarely improves care, and no currently available pharmacologic options have been proven to provide meaningful benefits or improve outcomes.

RECENT FINDINGS

Beta-agonists continue to be used frequently despite evidence that they do not reduce hospital admissions or length of stay. In general, therapies initially considered promising were subsequently proven ineffective, a pattern seen in studies on corticosteroids, and more recently with nebulized racemic epinephrine and hypertonic saline. Recent research has improved our understanding of the viral epidemiology of bronchiolitis, with increasing recognition of viruses other than respiratory syncytial virus and better awareness of the role of viral coinfections. How these findings will translate into improved outcomes remains uncertain.

SUMMARY

Much of the emphasis of the last few decades of bronchiolitis clinical care and research has centered on the identification and testing of novel therapies. Future quality improvement efforts should focus more on the limitation of unnecessary testing and treatments. Future research should include identification of subgroups of children with bronchiolitis that may benefit from focused clinical interventions.

Translational sciences approach to RSV vaccine development

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants and the elderly. Despite its relatively low degree of antigenic variation, it causes frequent reinfection throughout life. Clinical manifestations of RSV disease and the immune response to infection differ in infants and the elderly, suggesting that vaccines designed to protect these two populations may require different attributes. Here, the authors describe the translational approach of utilizing data from epidemiology studies performed in these populations, the use of RSV diagnostics in clinical practice, lessons learned from previous vaccine clinical trials and the success of palivizumab in prevention of RSV disease in premature and high-risk infants to aid the development of safe and effective RSV vaccines.

Respiratory viral infections in infants with clinically suspected pertussis

OBJECTIVE

to evaluate the frequency of respiratory viral infections in hospitalized infants with clinical suspicion of pertussis, and to analyze their characteristics at hospital admission and clinical outcomes.

METHODS

a historical cohort study was performed in a reference service for pertussis, in which the research of respiratory viruses was also a routine for infants hospitalized with respiratory problems. All infants reported as suspected cases of pertussis were included. Tests for Bordetella pertussis (BP) (polymerase chain reaction/culture) and for respiratory viruses (RVs) (immunofluorescence) were performed. Patients who received macrolides before hospitalization were excluded. Clinical data were obtained from medical records.

RESULTS

Among the 67 patients studied, BP tests were positive in 44%, and 26% were positive for RV. There was no etiological identification in 35%, and RV combined with BP was identified in 5%. All patients had similar demographic characteristics. Cough followed by inspiratory stridor or cyanosis was a strong predictor of pertussis, as well as prominent leukocytosis and lymphocytosis. Rhinorrhea and dyspnea were more frequent in viral infections. Macrolides were discontinued in 40% of patients who tested positive for RV and negative for BP.

CONCLUSION

the results suggest that viral infection can be present in hospitalized infants with clinical suspicion of pertussis, and etiological tests may enable a reduction in the use of macrolides in some cases. However, the etiological diagnosis of respiratory virus infection, by itself, does not exclude the possibility of infection with BP.

Respiratory syncytial virus detection in cells and clinical samples by using three new monoclonal antibodies

Acute respiratory infections caused by the respiratory syncytial virus (RSV) are important health burdens that affect infants worldwide. RSV is also an important cause of morbidity and disease in adults, which causes enormous economic losses. At the present time, RSV infection is diagnosed by immunofluorescence, test pack and/or PCR, obtaining better results with PCR than with any other technique. The production of new monoclonal antibodies (mAbs) capable of detecting RSV in clinical samples is necessary to generate better and faster diagnosis tools for RSV. In this study, three new mAbs, directed against the RSV N and M2-1 proteins, were evaluated for the detection of RSV in clinical samples. Nasopharyngeal swabs were obtained from: 27 RSV-positive patients; 15 human metapneumovirus (hMPV)-positive patients; and 6 healthy controls. To evaluate RSV presence in these samples, clinical samples and RSV-infected cells were tested by Enzyme-Linked ImmunoSorbent Assay (ELISA), flow cytometry, immunofluorescence, and dot-blot assays. Specificity and sensitivity were determined for each mAb by using purified RSV antigens and antigens from different viruses. Infected cells and clinical samples tested with the three new mAbs resulted positive by immunofluorescence, ELISA, flow cytometry, and dot blot. No false positives were obtained in samples infected with other respiratory virus (hMPV) or from healthy controls. These results suggest that these new anti-RSV mAbs can be considered for the rapid and reliable detection of RSV on infected cells and clinical specimens by multiple immunological approaches.

Laboratory testing trends for respiratory syncytial virus, 2007-2011

BACKGROUND

Antigen detection tests have been the most common diagnostic assay used to detect and diagnose respiratory syncytial virus (RSV). The utility and increased sensitivity of polymerase chain reaction (PCR) tests have been reported; however, their use in US hospital laboratories is not well characterized.

OBJECTIVE

To describe changes in RSV test types used by US hospital-affiliated laboratories, focusing on PCR testing prevalence.

STUDY DESIGN

Data were collected from 480 to 666 laboratories each RSV season (2007-2008 through 2010-2011) across 50 states, the District of Columbia, and Puerto Rico. A descriptive analysis was conducted using this convenience sample of RSV tests conducted from November to April each season. Total numbers and types of RSV tests performed were reported weekly and weekly proportions by test type were calculated. Kendall τ rank correlation was used to quantify associations between time and proportions of each test type.

RESULTS

PCR tests accounted for 2%, 3%, 16%, and 21% of weekly tests (total range, 381,068-481,654 over 4 seasons) conducted each season from 2007 to 2011, respectively. The proportion of laboratories reporting ≥1 PCR tests was 4%, 5%, 10%, and 16%, respectively. Decreases in antigen testing and viral culture were similarly observed.

CONCLUSIONS

Although antigen detection was the predominant test type reported in the sample of US hospital laboratories for RSV testing, PCR use increased to >20% of tests reported. These results demonstrate the increasing contribution of PCR to RSV surveillance. RSV surveillance systems relying solely on antigen detection results will not capture an increasing proportion of RSV test results.

The epidemiology and clinical characteristics of young children hospitalized with respiratory syncytial virus infections in Guatemala (2007-2010)

BACKGROUND

There have been few population-based studies from Central America on respiratory syncytial virus (RSV) infections in young children. We report population-based incidence rates and describe epidemiological and clinical characteristics of children <5 years old hospitalized with RSV infections in Guatemala.

METHODS

Prospective, active hospital-based surveillance for acute respiratory infections in children <5 years old was conducted at 3 hospitals in Guatemala from November 2007 through July 2010. RSV hospitalization rates were calculated for areas where the catchment population could be defined. Comparisons were made between children who were RSV-positive and RSV-negative.

RESULTS

RSV was detected in 549 (25%) of enrolled children. Overall, annual rates of RSV hospitalizations ranged from 5.9 to 45.9 and 2.0 to 13.7 per 1000 children <1 year old and <5 years old, respectively, but varied by location and calendar year. Rates generally decreased with age--children <6 months had rates up to 30 times higher than older children, but children >12 months old still had rates up to 5.5 per 1000 per year and accounted for 42% of deaths. Children with RSV infections were more likely to have signs of respiratory distress (85% versus 63%, P < 0.001) compared with those without RSV infections, but case fatality ratios were similar (3-4%).

CONCLUSIONS

The large burden and severity of RSV infections in young Guatemalan children is similar in magnitude and age distribution to RSV disease burdens found in other developing countries and suggests that this population would benefit from prevention strategies, including vaccines against RSV that are currently under development.

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.

Implementation of filmarray respiratory viral panel in a core laboratory improves testing turnaround time and patient care

The FilmArray respiratory virus panel detects 15 viral agents in respiratory specimens using polymerase chain reaction. We performed FilmArray respiratory viral testing in a core laboratory at a regional children’s hospital that provides service 24 hours a day 7 days a week. The average and median turnaround time were 1.6 and 1.4 hours, respectively, in contrast to 7 and 6.5 hours documented 1 year previously at an on-site reference laboratory using a direct fluorescence assay (DFA) that detected 8 viral agents. During the study period, rhinovirus was detected in 20% and coronavirus in 6% of samples using FilmArray; these viruses would not have been detected with DFA. We followed 97 patients with influenza A or influenza B who received care at the emergency department (ED). Overall, 79 patients (81%) were given oseltamivir in a timely manner defined as receiving the drug in the ED, a prescription in the ED, or a prescription within 3 hours of ED discharge. Our results demonstrate that molecular technology can be successfully deployed in a nonspecialty, high-volume, multidisciplinary core laboratory.

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.