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

Respiratory syncytial virus subtypes in children with bronchiolitis: does it correlate with clinical severity?

BACKGROUND

In this retrospective study, we aimed to evaluate the factors associated with the severity of respiratory syncytial virus (RSV) bronchiolitis in children aged under 2 years who were admitted to the Children's Hospital of Hebei between June 2018 and January 2019.

METHODS

Sputum samples positive for RSV via multiplex PCR were subtyped using real-time PCR. Data collected included risk factors for disease severity, demographics, microbiology, and outcomes.

RESULTS

Of the 82 children with RSV bronchiolitis, 79 were treated and discharged with improvement, while 3 died. All three patients had underlying medical conditions, including complex congenital heart disease and severe combined immunodeficiency. Further, disease severity was associated with preexisting underlying disease, fever duration, and bacterial co-infection, but not with the RSV subtype.

CONCLUSIONS

Our findings suggest that an appropriate therapeutic regimen should include the detection of bacterial co-infections and the identification of underlying diseases for the effective management of severe RSV bronchiolitis.

A Rare Association: Non-ST Elevation Myocardial Infarction (NSTEMI) Secondary to Respiratory Syncytial Virus (RSV) Infection

We present a case report on a rare association between non-ST elevation myocardial infarction (NSTEMI) and respiratory syncytial virus (RSV) infection in a patient with no traditional risk factors for cardiovascular disease (CVD) including a family history of premature coronary artery disease (CAD). While RSV is commonly known for its respiratory manifestations, it has been increasingly recognized as a cause of significant morbidity and mortality in adults, particularly those with underlying comorbidities. However, the association between RSV infection and NSTEMI, especially in patients without traditional risk factors, remains relatively unexplored. Our case involves a 31-year-old healthy adult who presented with progressive exertional chest pain and flu-like symptoms. Electrocardiogram (EKG) changes and elevated troponin levels indicated NSTEMI. Laboratory tests confirmed RSV infection. Angiography revealed significant coronary artery disease requiring percutaneous coronary intervention. This case highlights the need for healthcare professionals to be aware of the potential cardiovascular (CV) complications associated with RSV infection, even in patients without traditional risk factors. It expands our understanding of viral respiratory infections as potential triggers for acute coronary syndromes (ACS) and emphasizes the importance of considering RSV infection in the differential diagnosis of NSTEMI, especially in young otherwise healthy individuals. Further research is warranted to explore the underlying mechanisms and develop preventive strategies for RSV-related cardiovascular complications.

Innate immune pathway modulator screen identifies STING pathway activation as a strategy to inhibit multiple families of arbo and respiratory viruses

RNA viruses continue to remain a threat for potential pandemics due to their rapid evolution. Potentiating host antiviral pathways to prevent or limit viral infections is a promising strategy. Thus, by testing a library of innate immune agonists targeting pathogen recognition receptors, we observe that Toll-like receptor 3 (TLR3), stimulator of interferon genes (STING), TLR8, and Dectin-1 ligands inhibit arboviruses, Chikungunya virus (CHIKV), West Nile virus, and Zika virus to varying degrees. STING agonists (cAIMP, diABZI, and 2',3'-cGAMP) and Dectin-1 agonist scleroglucan demonstrate the most potent, broad-spectrum antiviral function. Furthermore, STING agonists inhibit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and enterovirus-D68 (EV-D68) infection in cardiomyocytes. Transcriptome analysis reveals that cAIMP treatment rescue cells from CHIKV-induced dysregulation of cell repair, immune, and metabolic pathways. In addition, cAIMP provides protection against CHIKV in a chronic CHIKV-arthritis mouse model. Our study describes innate immune signaling circuits crucial for RNA virus replication and identifies broad-spectrum antivirals effective against multiple families of pandemic potential RNA viruses.

Broad-spectrum antiviral inhibitors targeting pandemic potential RNA viruses

RNA viruses continue to remain a clear and present threat for potential pandemics due to their rapid evolution. To mitigate their impact, we urgently require antiviral agents that can inhibit multiple families of disease-causing viruses, such as arthropod-borne and respiratory pathogens. Potentiating host antiviral pathways can prevent or limit viral infections before escalating into a major outbreak. Therefore, it is critical to identify broad-spectrum antiviral agents. We have tested a small library of innate immune agonists targeting pathogen recognition receptors, including TLRs, STING, NOD, Dectin and cytosolic DNA or RNA sensors. We observed that TLR3, STING, TLR8 and Dectin-1 ligands inhibited arboviruses, Chikungunya virus (CHIKV), West Nile virus (WNV) and Zika virus, to varying degrees. Cyclic dinucleotide (CDN) STING agonists, such as cAIMP, diABZI, and 2',3'-cGAMP, and Dectin-1 agonist scleroglucan, demonstrated the most potent, broad-spectrum antiviral function. Comparative transcriptome analysis revealed that CHIKV-infected cells had larger number of differentially expressed genes than of WNV and ZIKV. Furthermore, gene expression analysis showed that cAIMP treatment rescued cells from CHIKV-induced dysregulation of cell repair, immune, and metabolic pathways. In addition, cAIMP provided protection against CHIKV in a CHIKV-arthritis mouse model. Cardioprotective effects of synthetic STING ligands against CHIKV, WNV, SARS-CoV-2 and enterovirus D68 (EV-D68) infections were demonstrated using human cardiomyocytes. Interestingly, the direct-acting antiviral drug remdesivir, a nucleoside analogue, was not effective against CHIKV and WNV, but exhibited potent antiviral effects against SARS-CoV-2, RSV (respiratory syncytial virus), and EV-D68. Our study identifies broad-spectrum antivirals effective against multiple families of pandemic potential RNA viruses, which can be rapidly deployed to prevent or mitigate future pandemics.

Cardiac function in bronchiolitis: Not only a right ventricle matter

OBJECTIVES

Extrapulmonary manifestations of bronchiolitis have been previously studied, with some identifying right ventricle (RV) diastolic/systolic dysfunction. We hypothesized that severe cases of bronchiolitis would have cardiac dysfunction resulting an increase in N-terminal pro-hormone B-type natriuretic peptide (NT-proBNP) values and worse outcomes. Therefore, the objective was to evaluate the existence of cardiac dysfunction and to determine its association with severe bronchiolitis.

METHODS

This prospective cohort study included children hospitalized for bronchiolitis under 1-year old between January 2019 and March 2020. At admission, an echocardiography was performed and plasma levels of NT-proBNP were measured. To analyze outcomes, the cohort was divided into two groups based on the need for positive pressure respiratory support (PPRS), and both were compared to healthy infants.

STATISTICS

bivariant analysis, significant differences p < 0.05.

RESULTS

One hundred eighty-one patients were included; median age was 2 months. Seventy-three patients required PPRS. Compared to controls, patients requiring PPRS showed worse RV systolic function, with lower tricuspid annular-plane systolic excursion (p = 0.002) and parameters of worse right and left diastolic function (trans-tricuspid E and A wave [p = 0.004 and p = 0.04, respectively] and tricuspid tissue doppler imaging [TDI] e' [p = 0.003], trans-mitral E and mitral TDI a' [p = 0.02 and p = 0.005, respectively]). An NT-ProBNP greater than 3582 pg/dl predicts the need for longer necessity of PPRS in patients younger than 2 months.

CONCLUSIONS

In addition to the expected RV systolic dysfunction, patients with severe bronchiolitis have parameters of global diastolic worse function possibly secondary to intrinsic myocardial involvement. NT-ProBNP values at admission had strong discriminatory power to predict worse outcomes.

Micro-Players of Great Significance-Host microRNA Signature in Viral Infections in Humans and Animals

Over time, more and more is becoming known about micro-players of great significance. This is particularly the case for microRNAs (miRNAs; miR), which have been found to participate in the regulation of many physiological and pathological processes in both humans and animals. One such process is viral infection in humans and animals, in which the host miRNAs—alone or in conjunction with the virus—interact on two levels: viruses may regulate the host’s miRNAs to evade its immune system, while the host miRNAs can play anti- or pro-viral roles. The purpose of this comprehensive review is to present the key miRNAs involved in viral infections in humans and animals. We summarize the data in the available literature, indicating that the signature miRNAs in human viral infections mainly include 12 miRNAs (i.e., miR-155, miR-223, miR-146a, miR-122, miR-125b, miR-132, miR-34a, miR -21, miR-16, miR-181 family, let-7 family, and miR-10a), while 10 miRNAs are commonly found in animals (i.e., miR-155, miR-223, miR-146a, miR-145, miR-21, miR-15a/miR-16 cluster, miR-181 family, let-7 family, and miR-122) in this context. Knowledge of which miRNAs are involved in different viral infections and the biological functions that they play can help in understanding the pathogenesis of viral diseases, facilitating the future development of therapeutic agents for both humans and animals.

Exploring the management approaches of cytokines including viral infection and neuroinflammation for neurological disorders

Considerable evidence supports that cytokines are important mediators of pathophysiologic processes within the central nervous system (CNS). Numerous studies have documented the increased production of various cytokines in the human CNS in various neurological and neuropsychiatric disorders. Deciphering cytokine actions in the intact CNS has important implications for our understanding of the pathogenesis and treatment of these disorders. The purpose of this study is to discuss the recent research on treating cytokine storm and amyloids, including stroke, Parkinson's disease (PD), Alzheimer's disease (AD), Huntington's condition, Multi-sclerosis (MS), Amyotrophic Lateral Sclerosis (ALS). Neuroinflammation observed in neurological disorders has a pivotal role in exacerbating Aβ burden and tau hyperphosphorylation, suggesting that stimulating cytokines in response to an undesirable external response could be a checkpoint for treating neurological disorders. Furthermore, the pro-inflammatory cytokines help our immune system through a neuroprotective mechanism in clearing viral infection by recruiting mononuclear cells. This study reveals that cytokine applications may play a vital role in providing novel regulation and methods for the therapeutic approach to neurological disorders and the causes of the deregulation, which is responsible for neuroinflammation and viral infection. However, it needs to be further investigated to clarify better the mechanisms of cytokine release in response to various stimuli, which could be the central point for treating neurological disorders.

Cardiac Complications Caused by Respiratory Syncytial Virus Infection: Questionnaire Survey and a Literature Review

We investigated 22 cases of patients with myocarditis during respiratory syncytial virus (RSV) infection by a questionnaire survey, and performed a literature search to clarify their characteristics. The age distribution was divided into 2 groups, that is, 1 group comprised of patients younger than 4-years old and the other comprised patients older than 15 years. ECG demonstrated disturbance of the conduction system (AV block) in 7 out of 18 patients (38.8%), myocardial damage (ST-T change) in 9 out of 18 patients (50.0%), and tachycardia in 3 out of 18 patients (16.6%). Echocardiography displayed a robust decrease in left-heart function in 12 out of 14 patients. The outcome was 2 deaths, 1 pacemaker placement, 4 patients with mild sequel. Our data suggest that RSV myocarditis caused by RSV infection can be divided into 3 different pathophysiologies, characterized by disturbance of the conduction system, myocardial damage, and increase of autonomy.

Early elevated NT-proBNP but not troponin I is associated with severe bronchiolitis in infants

BACKGROUND

We aimed to explore and to compare the association between the NT-proBNP and high-sensitivity troponin I (hs-cTnI) at early stages of acute bronchiolitis with echocardiographic alterations, clinical severity and outcomes.

METHODS

A single centre, prospective observational study including previously healthy infants aged 1-12 months with bronchiolitis admitted to a tertiary hospital from April 2019 to March 2020. All patients underwent clinical, laboratory and echocardiographic evaluation at the same time point within 12 h of hospital admission. NT-proBNP > 1121 pg/ml and hs-cTnI > 26 ng/L were considered elevated. The primary outcome measure was the association of raised cardiac biomarkers with the need for PICU admission.

RESULTS

We enrolled 40 infants with median levels of NT-proBNP of 1176 (520-3030) pg/ml and hs-cTnI of 11.5 (5-21) ng/L at the time of hospital admission. Raised levels of NT-proBNP and hs-cTnI in 50% and 20% of cases, respectively. Of them, 15 (37%) required PICU admission during the hospitalization. Increased NT-proBNP was associated with PICU admission (adjusted OR 9.5 (CI95% 1.4-64); p = 0.020), prolonged hospitalization (β = 2.7; p = 0.012) and duration of oxygen administration (β = 2.7; p = 0.004) in the multivariate analysis. There were no differences in hs-cTnI levels regarding PICU admission (p = 0.866). Increased hs-cTnI levels were only associated with oxygen administration duration (Spearman rho = 0.38; p = 0.017), but this association disappeared in the multivariate analysis. Only NT-proBNP was associated with echocardiographic parameters of myocardial dysfunction (p < 0.001), and pulmonary hypertension (p < 0.001) CONCLUSION: Early elevated NT-proBNP but not hs-cTnI could be used as a biomarker for myocardial strain and disease severity in bronchiolitis.

The Assessment of Myocardial Strain by Cardiac Imaging in Healthy Infants with Acute Bronchiolitis: A Systematic Review and Meta-Analysis

This study aims to systematically review the incidence of myocardial strain detected by echocardiography in previously healthy infants with acute bronchiolitis and its role as a predictor for adverse outcomes in this setting.

METHODS

Pubmed/Medline, Excerpta Medica Data Base (EMBASE), and Cochrane Library were searched in April 2020 to identify original observational prospective studies that systematically performed echocardiography for the screening of myocardial strain in healthy infants with acute bronchiolitis. Pooled estimates were generated using random-effects models. Heterogeneity within studies was assessed using Cochran's Q and I² statistics. Funnel plots and Egger´s regression method were constructed to evaluate publication bias. Sensitivity analyses were also conducted to evaluate potential sources of heterogeneity.

RESULTS

After a detailed screening of 305 articles, a total of 10 studies with 395 participants (mean of 40 participants per study) was included. Five of them were classified as high-quality studies. Up to 28% of cases presented adverse outcomes. The echocardiographic screening for myocardial strain was performed within the first 24 h of admission in 92% cases. Tissue Doppler imaging and Speckle-Tracking echocardiography were performed only in 20% of cases. The presence of pulmonary hypertension was evaluated with methods different from the tricuspid regurgitation jet in 64% of cases. Seven studies found some grade of myocardial strain with a pooled incidence of 21% (CI 95%, 11-31%), in the form of pulmonary hypertension (pooled incidence of 20% (CI 95%, 11-30%)), and myocardial dysfunction (pooled incidence of 5% (CI 95%, 1-9%)). The presence of these echocardiographic alterations was associated with adverse outcomes (pooled relative risk = 16; CI 95%, 8.2-31.5). After a subgroup analysis based on the echocardiographic techniques used, no significant heterogeneity across the studies was observed. There was no evidence of publication bias when assessed by Egger´s test. Cardiac biomarkers to assess myocardial strain were used in five studies. Only N-terminal-pro-brain natriuretic peptide accurately predicted the presence of myocardial strain by echocardiography.

CONCLUSIONS

Myocardial strain is not infrequent in previously healthy infants with acute bronchiolitis, and it could be present at the early stages of the disease with prognostic implications. There is a need for sufficiently powered prospective studies with a similar methodology, preferably employing advanced imaging techniques, to conclusively address the usefulness of the assessment of myocardial strain in this setting.

Respiratory syncytial virus tropism for olfactory sensory neurons in mice

The olfactory mucosa, where the first step of odor detection occurs, is a privileged pathway for environmental toxicants and pathogens toward the central nervous system. Indeed, some pathogens can infect olfactory sensory neurons including their axons projecting to the olfactory bulb allowing them to bypass the blood-brain barrier and reach the central nervous system (CNS) through the so-called olfactory pathway. The respiratory syncytial virus (RSV) is a major respiratory tract pathogen but there is growing evidence that RSV may lead to CNS impairments. However, the mechanisms involved in RSV entering into the CNS have been poorly described. In this study, we wanted to explore the capacity of RSV to reach the CNS via the olfactory pathway and to better characterize RSV cellular tropism in the nasal cavity. We first explored the distribution of RSV infectious sites in the nasal cavity by in vivo bioluminescence imaging and a tissue clearing protocol combined with deep-tissue imaging and 3D image analyses. This whole tissue characterization was confirmed with immunohistochemistry and molecular biology approaches. Together, our results provide a novel 3D atlas of mouse nasal cavity anatomy and show that RSV can infect olfactory sensory neurons giving access to the central nervous system by entering the olfactory bulb. Cover Image for this issue: doi: 10.1111/jnc.14765.

Respiratory syncytial virus-associated mortality in a healthy 3-year-old child: a case report

Background

Respiratory syncytial virus (RSV) is the most frequently identified pathogen in children with acute lower respiratory tract infection. Fatal cases have mainly been reported during the first 6 months of life or in the presence of comorbidity.

Case presentation

A 47-month-old girl was admitted to the pediatric intensive care unit following sudden cardiopulmonary arrest occurring at home. The electrocardiogram showed cardiac asystole, which was refractory to prolonged resuscitation efforts. Postmortem analyses detected RSV by polymerase chain reaction in an abundant, exudative pericardial effusion. Histopathological examination was consistent with viral myoepicarditis, including an inflammatory process affecting cardiac nerves and ganglia. Molecular analysis of sudden unexplained death genes identified a heterozygous mutation in myosin light chain 2, which was also found in two other healthy members of the family. Additional expert interpretation of the cardiac histology confirmed the absence of arrhythmogenic right ventricular dysplasia or hypertrophic cardiomyopathy.

Conclusions

RSV-related sudden death in a normally developing child of this age is exceptional. This case highlights the risk of extrapulmonary manifestations associated with this infection, particularly arrhythmia induced by inflammatory phenomena affecting the cardiac autonomic nervous system. The role of the mutation in this context is uncertain, and it is therefore necessary to continue to assess how this pathogenic variant contributes to unexpected sudden death in childhood.

Acute Encephalitis and Myocarditis Associated with Respiratory Syncytial Virus Infections

Respiratory syncytial virus (RSV) is one of the most common causes of acute respiratory tract infections among children. 1%-2% of RSV infections require hospitalization. In addition to the respiratory system, cardiovascular system may be also affected by the RSV infection. A 7-year-old, previously healthy, female patient presenting with respiratory difficulties was admitted to the paediatric intensive care unit. The patient was intubated and connected to a mechanical ventilator because of acute respiratory failure. Her tracheal aspirate was studied for viral multiplex polymerase chain reaction (PCR), and RSV positivity was detected. Her echocardiogram revealed left ventricular dysfunction. She was put on fluid restriction, intravenous furosemide, and inotropic support. Her cranial magnetic resonance examination showed the signs of acute haemorrhagic encephalopathy. She underwent five sessions of therapeutic plasma exchange with fresh frozen plasma. She was extubated on the 18^th day of admission and provided with respiratory support with high-flow oxygen therapy thereafter. On the 23^rd day, when her clinical status remained stable, she was transferred to the paediatrics ward. An RSV infection should be considered in cases with acute necrotising encephalitis and myocarditis.

Left Ventricular Dysfunction and Plasmatic NT-proBNP Are Associated with Adverse Evolution in Respiratory Syncytial Virus Bronchiolitis

AIM

To investigate whether the presence of left ventricular myocardial dysfunction (LVMD) assessed by Tei index (LVTX) impacts the outcomes of healthy infants with Respiratory Syncytial Virus Bronchiolitis (RSVB). To explore whether N-terminal pro-B-type natriuretic peptide (NT-proBNP) increases the accuracy of traditional clinical markers in predicting the outcomes.

METHODS

A single-centre, prospective, cohort study including healthy infants aged 1-12 months old admitted for RSVB between 1 October 2016 and 1 April 2017. All patients underwent clinical, laboratory and echocardiographic evaluation within 24 h of admission. Paediatric intensive care unit (PICU) admission was defined as severe disease.

RESULTS

We enrolled 50 cases of RSVB (median age of 2 (1-6.5) months; 40% female) and 50 age-matched controls. We observed higher values of LVTX in infants with RSVB than in controls (0.42 vs. 0.36; p = 0.008). Up to nine (18%) children presented with LVMD (LVTX > 0.5), with a higher incidence of PICU admission (89% vs. 5%; p < 0.001). The diagnostic performance of NT-proBNP in predicting LVMD was high (area under the receiver operator characteristic curve (AUC) 0.95, CI 95% 0.90-1). The diagnostic yield of the predictive model for PICU admission that included NT-proBNP was excellent (AUC 0.945, CI 95% 0.880-1), and significantly higher than the model without NT-proBNP (p = 0.026).

CONCLUSIONS

LVMD could be present in healthy infants with RSVB who develop severe disease. NT-proBNP seems to improve traditional clinical markers for outcomes.

Respiratory Syncytial Virus and Associations With Cardiovascular Disease in Adults

Respiratory syncytial virus (RSV) is historically known for causing respiratory illness in young children, but the appreciation of its impact on older adults is growing. Studies have shown that hospitalization for respiratory illness due to RSV is complicated by cardiovascular events in 14% to 22% of adult patients, including worsening congestive heart failure, acute coronary syndrome, and arrhythmias. Additionally, underlying cardiovascular disease is associated with hospitalization in 45% to 63% of adults with confirmed RSV. In summary, patients with cardiopulmonary disease have higher rates of health care utilization for RSV-related illness and worse outcomes. Patients with cardiovascular disease likely represent an important target population for the rapidly developing field of RSV vaccines.

The BeWo cell line derived from a human placental choriocarcinoma is permissive for respiratory syncytial virus infection

The respiratory syncytial virus (RSV) is the main pathogen associated with upper respiratory tract infections during early childhood. Vertical transmission of this virus has been suggested in humans, based on observations recorded during animal studies that revealed an association of RSV with persistent structural and functional changes in the developing lungs of the offspring. However, human placentas have not yet been evaluated for susceptibility to RSV infection. In this study, we examined the capacity of RSV to infect a human trophoblast model, the BeWo cell line. Our results suggest that BeWo cells are susceptible to RSV infection since they allow RNA viral replication, viral protein translation, leading to the production of infectious RSV particles. In this report, we demonstrate that a human placenta model system, consisting of BeWo cells, is permissive to RSV infection. Thus, the BeWo cell line may represent a useful model for studies that aim to characterize the events of a possible RSV infection at the human maternal-fetal interface.

Neurologic Alterations Due to Respiratory Virus Infections

Central Nervous System (CNS) infections are one of the most critical problems in public health, as frequently patients exhibit neurologic sequelae. Usually, CNS pathologies are caused by known neurotropic viruses such as measles virus (MV), herpes virus and human immunodeficiency virus (HIV), among others. However, nowadays respiratory viruses have placed themselves as relevant agents responsible for CNS pathologies. Among these neuropathological viruses are the human respiratory syncytial virus (hRSV), the influenza virus (IV), the coronavirus (CoV) and the human metapneumovirus (hMPV). These viral agents are leading causes of acute respiratory infections every year affecting mainly children under 5 years old and also the elderly. Up to date, several reports have described the association between respiratory viral infections with neurological symptoms. The most frequent clinical manifestations described in these patients are febrile or afebrile seizures, status epilepticus, encephalopathies and encephalitis. All these viruses have been found in cerebrospinal fluid (CSF), which suggests that all these pathogens, once in the lungs, can spread throughout the body and eventually reach the CNS. The current knowledge about the mechanisms and routes used by these neuro-invasive viruses remains scarce. In this review article, we describe the most recent findings associated to neurologic complications, along with data about the possible invasion routes of these viruses in humans and their various effects on the CNS, as studied in animal models.

Respiratory virus prophylaxis in congenital heart disease

Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infections and causes up to 200,000 infant deaths a year worldwide. The average rate of hospitalization for severe RSV infection is 5 per 1000 children, and the rate is three-times higher in those with congenital heart disease (CHD). Palivizumab, a monoclonal antibody, reduces hospitalization rates and intensive care admissions. It is used prophylactically and is administered as monthly doses during the RSV season. Hemodynamically unstable CHD is the most susceptible CHD to a severe episode of RSV infection. This review explores current evidence surrounding therapies, patterns of infection and identifies groups which may still be vulnerable to severe RSV infection.

Complete heart block complicating the acute phase of respiratory syncytial virus bronchiolitis

Respiratory syncytial virus is the most common pathogen causing lower respiratory tract infection in infants. In recent years, the importance of extrapulmonary complications and longterm sequelae including those involving the cardiovascular system has become apparent. We report on a 10 month old infant with respiratory syncytial virus bronchiolitis, the acute phase of which was complicated by irreversible complete heart block, which was managed conservatively.

CHD and respiratory syncytial virus: global expert exchange recommendations

BACKGROUND

Palivizumab is the standard immunoprophylaxis against serious disease due to respiratory syncytial virus infection. Current evidence-based prophylaxis guidelines may not address certain children with CHD within specific high-risk groups or clinical/management settings.

METHODS

An international steering committee of clinicians with expertise in paediatric heart disease identified key questions concerning palivizumab administration; in collaboration with an additional international expert faculty, evidence-based recommendations were formulated using a quasi-Delphi consensus methodology.

RESULTS

Palivizumab prophylaxis was recommended for children with the following conditions: <2 years with unoperated haemodynamically significant CHD, who are cyanotic, who have pulmonary hypertension, or symptomatic airway abnormalities; <1 year with cardiomyopathies requiring treatment; in the 1st year of life with surgically operated CHD with haemodynamically significant residual problems or aged 1-2 years up to 6 months postoperatively; and on heart transplant waiting lists or in their 1st year after heart transplant. Unanimous consensus was not reached for use of immunoprophylaxis in children with asymptomatic CHD and other co-morbid factors such as arrhythmias, Down syndrome, or immunodeficiency, or during a nosocomial outbreak. Challenges to effective immunoprophylaxis included the following: multidisciplinary variations in identifying candidates with CHD and prophylaxis compliance; limited awareness of severe disease risks/burden; and limited knowledge of respiratory syncytial virus seasonal patterns in subtropical/tropical regions.

CONCLUSION

Evidence-based immunoprophylaxis recommendations were formulated for subgroups of children with CHD, but more data are needed to guide use in tropical/subtropical countries and in children with certain co-morbidities.

Immunological Features of Respiratory Syncytial Virus-Caused Pneumonia-Implications for Vaccine Design

The human respiratory syncytial virus (hRSV) is the causative agent for high rates of hospitalizations due to viral bronchiolitis and pneumonia worldwide. Such a disease is characterized by an infection of epithelial cells of the distal airways that leads to inflammation and subsequently to respiratory failure. Upon infection, different pattern recognition receptors recognize the virus and trigger the innate immune response against the hRSV. Further, T cell immunity plays an important role for virus clearance. Based on animal studies, it is thought that the host immune response to hRSV is based on a biased T helper (Th)-2 and Th17 T cell responses with the recruitment of T cells, neutrophils and eosinophils to the lung, causing inflammation and tissue damage. In contrast, human immunity against RSV has been shown to be more complex with no definitive T cell polarization profile. Nowadays, only a humanized monoclonal antibody, known as palivizumab, is available to protect against hRSV infection in high-risk infants. However, such treatment involves several injections at a significantly high cost. For these reasons, intense research has been focused on finding novel vaccines or therapies to prevent hRSV infection in the population. Here, we comprehensively review the recent literature relative to the immunological features during hRSV infection, as well as the new insights into preventing the disease caused by this virus.

Clinical presentation and microbiological diagnosis in paediatric respiratory tract infection: a systematic review

BACKGROUND

Antibiotic prescribing decisions for respiratory tract infection (RTI) in primary care could be improved if clinicians could target bacterial infections. However, there are currently no evidence-based diagnostic rules to identify microbial aetiology in children presenting with acute RTIs.

AIM

To analyse evidence of associations between clinical symptoms or signs and detection of microbes from the upper respiratory tract (URT) of children with acute cough.

DESIGN AND SETTING

Systematic review and meta-analysis.

METHOD

A literature search identified articles reporting relationships between individual symptoms and/or signs, and microbes detected from URT samples. Associations between pathogens and symptoms or signs were summarised, and meta-analysis conducted where possible.

RESULTS

There were 9984 articles identified, of which 28 met inclusion criteria. Studies identified 30 symptoms and 41 signs for 23 microbes, yielding 1704 potential associations, of which only 226 (13%) have presently been investigated. Of these, relevant statistical analyses were presented for 175 associations, of which 25% were significant. Meta-analysis demonstrated significant relationships between respiratory syncytial virus (RSV) detection and chest retractions (pooled odds ratio [OR] 1.9, 95% confidence interval [CI] = 1.6 to 2.3), wheeze (pooled OR 1.7, 95% CI = 1.5 to 2.0), and crepitations/crackles (pooled OR 1.7, 95% CI = 1.3 to 2.2).

CONCLUSIONS

There was an absence of evidence for URT pathogens other than RSV. The meta-analysis identified clinical signs associated with RSV detection, suggesting clinical presentation may offer some, albeit poor, diagnostic value. Further research is urgently needed to establish the value of symptoms and signs in determining microbiological aetiology and improve targeting of antibiotics in primary care.

Human Respiratory Syncytial Virus: Infection and Pathology

The human respiratory syncytial virus (hRSV) is by far the major cause of acute lower respiratory tract infections (ALRTIs) worldwide in infants and children younger than 2 years. The overwhelming number of hospitalizations due to hRSV-induced ALRTI each year is due, at least in part, to the lack of licensed vaccines against this virus. Thus, hRSV infection is considered a major public health problem and economic burden in most countries. The lung pathology developed in hRSV-infected individuals is characterized by an exacerbated proinflammatory and unbalanced Th2-type immune response. In addition to the adverse effects in airway tissues, hRSV infection can also cause neurologic manifestations in the host, such as seizures and encephalopathy. Although the origins of these extrapulmonary symptoms remain unclear, studies with patients suffering from neurological alterations suggest an involvement of the inflammatory response against hRSV. Furthermore, hRSV has evolved numerous mechanisms to modulate and evade the immune response in the host. Several studies have focused on elucidating the interactions between hRSV virulence factors and the host immune system, to rationally design new vaccines and therapies against this virus. Here, we discuss about the infection, pathology, and immune response triggered by hRSV in the host.

Biomarkers of respiratory syncytial virus (RSV) infection: specific neutrophil and cytokine levels provide increased accuracy in predicting disease severity

Despite fundamental advances in the research on respiratory syncytial virus (RSV) since its initial identification almost 60 years ago, recurring failures in developing vaccines and pharmacologic strategies effective in controlling the infection have allowed RSV to become a leading cause of global infant morbidity and mortality. Indeed, the burden of this infection on families and health care organizations worldwide continues to escalate and its financial costs are growing. Furthermore, strong epidemiologic evidence indicates that early-life lower respiratory tract infections caused by RSV lead to the development of recurrent wheezing and childhood asthma. While some progress has been made in the identification of reliable biomarkers for RSV bronchiolitis, a "one size fits all" biomarker capable of accurately and consistently predicting disease severity and post-acute outcomes has yet to be discovered. Therefore, it is of great importance on a global scale to identify useful biomarkers for this infection that will allow pediatricians to cost-effectively predict the clinical course of the disease, as well as monitor the efficacy of new therapeutic strategies.

Central nervous system alterations caused by infection with the human respiratory syncytial virus

Worldwide, the human respiratory syncytial virus (hRSV) is the leading cause of infant hospitalization because of acute respiratory tract infections, including severe bronchiolitis and pneumonia. Despite intense research, to date there is neither vaccine nor treatment available to control hRSV disease burden globally. After infection, an incubation period of 3-5 days is usually followed by symptoms, such as cough and low-grade fever. However, hRSV infection can also produce a larger variety of symptoms, some of which relate to the individual's age at infection. Indeed, infants can display severe symptoms, such as dyspnea and chest wall retractions. Upon examination, crackles and wheezes are also common features that suggest infection by hRSV. Additionally, infection in infants younger than 1 year is associated with several non-specific symptoms, such as failure to thrive, periodic breathing or apnea, and feeding difficulties that usually require hospitalization. Recently, neurological symptoms have also been associated with hRSV respiratory infection and include seizures, central apnea, lethargy, feeding or swallowing difficulties, abnormalities in muscle tone, strabismus, abnormalities in the CSF, and encephalopathy. Here, we discuss recent findings linking the neurological, extrapulmonary effects of hRSV with infection and functional impairment of the CNS.

Pericardial effusion in an infant with severe respiratory syncytial virus bronchiolitis

Respiratory syncytial virus is the most common pathogen causing lower respiratory tract infection in infants. Respiratory syncytial virus infection is also associated with a number of extrapulmonary manifestations, including the cardiac system. Pericardial effusion, however, is a very rare occurrence with respiratory syncytial virus infection. We report a very young infant with respiratory syncytial virus bronchiolitis whose clinical course was associated with pericardial effusion, treated conservatively.

Prolonged sinoatrial block in an infant with respiratory syncytial viral bronchiolitis

Complete heart block in children admitted to the pediatric intensive care unit with respiratory syncytial viral (RSV) infections has been described. This report describes a prolonged sinoatrial block exceeding 4 s in an infant with RSV, which, to the authors' knowledge, is the longest such event described in the published literature. This block was followed by shorter episodes within the next 24 h. An extensive workup showed no other known cause of bradycardia or sinoatrial block. The infant was discharged home with 48 h Holter monitoring, which was normal. At this writing, the infant has remained asymptomatic since discharge. Respiratory syncytial viral infections may cause prolonged sinoatrial block in an otherwise healthy child.

Managing the morbidity associated with respiratory viral infections in children with congenital heart disease

Children with congenital heart disease (CHD) are at risk for increased morbidity from viral lower respiratory tract infections because of anatomical cardiac lesions than can worsen an already compromised respiratory status. Respiratory syncytial virus (RSV) remains an important pathogen in contributing toward the morbidity in this population. Although the acute treatment of RSV largely remains supportive, the development of monoclonal antibodies, such as palivuzumab, has reduced the RSV-related hospitalization rate in children with CHD. This review highlights the specific cardiac complications of RSV infection, the acute treatment of bronchiolitis in patients with CHD, and the search for new therapies against RSV, including an effective vaccine, because of the high cost associated with immunoprophylaxis and its lack of reducing RSV-related mortality.

Inflammatory responses to acute pneumovirus infection in neonatal mice

Background

The innate immune responses of neonates differ dramatically from those of adults. Here we examine the acute inflammatory responses of neonatal and weanling mice infected with pneumonia virus of mice (PVM), a rodent pathogen (family Paramyxoviridae, genus Pneumovirus) that replicates the sequelae of severe respiratory syncytial virus infection.

Results

We demonstrate that virus replication proceeds indistinguishably in all age groups (inoculated at 1, 2, 3 and 4 weeks of age), although inflammatory responses vary in extent and character. Some of the biochemical mediators detected varied minimally with age at inoculation. Most of the mediators evaluated demonstrated elevated expression over baseline correlating directly with age at the time of virus inoculation. Among the latter group are CCL2, CCL3, and IFN-γ, all cytokines previously associated with PVM-induced inflammatory pathology in mature mice. Likewise, we detect neutrophil recruitment to lung tissue in all age groups, but recruitment is most pronounced among the older (3 - 4 week old) mice. Interestingly, all mice exhibit failure to thrive, lagging in expected weight gain for given age, including the youngest mice that present little overt evidence of inflammation.

Conclusions

Our findings among the youngest mice may explain in part the phenomenon of atypical or minimally symptomatic respiratory infections in human neonates, which may be explored further with this infection model.