Role of viruses and atypical bacteria in exacerbations of asthma in hospitalized children: a prospective study in the Nord-Pas de Calais region (France)

We studied the role of viruses and atypical bacteria in children hospitalized with exacerbated asthma by a prospective study of children with acute asthma admitted to the Department of Pediatrics in Lille, and to 15 hospitals in the Nord-Pas de Calais region, from October 1, 1998-June 30, 1999. We included children aged 2-16 years with active asthma, defined as three or more recurrent episodes of reversible wheezing. The severity of asthma and of asthmatic exacerbations was recorded. Immunofluorescence assays (IFA) on nasopharyngeal secretions (NPS), serological tests, or both, were used for detection of influenza virus, respiratory syncytial virus (RSV), adenovirus, parainfluenza virus, and coronavirus. Polymerase chain reaction (PCR) assays on NPS were used for rhinovirus and enterovirus. Serological tests for Chlamydia pneumoniae and Mycoplasma pneumoniae were performed. A control group of asymptomatic asthmatic outpatients was examined for respiratory viruses (using IFA and PCR). Eighty-two symptomatic children (mean age, 7.9 years) were examined. Viruses were detected in 38% (enterovirus, 15.8%; rhinovirus, 12%; RSV, 7.3%). Serological tests for atypical bacteria were positive in 10% of patients (C. pneumoniae, 5%; M. pneumoniae, 5%). Among the 27 control subjects (mean age, 7.9 years), one PCR was positive for enterovirus. There was no correlation between severity of chronic asthma or asthmatic exacerbations and the diagnosis of infection. Atypical bacterial pathogen infections were linked with prolonged asthmatic symptoms. In conclusion, we confirmed the high incidence of viral infection in acute exacerbations of asthma, especially enteroviruses or rhinoviruses. Persistent clinical features were more frequently associated with atypical bacterial infections, suggesting that these infections should be investigated and treated in cases of persistent asthmatic symptoms.     

Viral "bronchitis" in childhood: relationship to asthma and obstructive lung disease

Lower respiratory tract infections in children, including group, bronchiolitis, and bronchitis are frequently associated with recurrent episodes of wheezing. Different respiratory viruses assume greater importance at different ages of children. Respiratory syncytial virus is the most prevalent viral respiratory infection in preschool children, while rhinovirus is of increasing importance in older children. Asymptomatic virus shedding and mild respiratory infections do not provoke asthma symptoms nor do bacteria, except in association with sinusitis. Furthermore, epidemiologic studies strongly suggest that viral lower respiratory tract illness in early childhood is associated with pulmonary abnormalities, including bronchial hyperreactivity and peripheral airway obstruction that may persist for many years, and is possibly a cause of chronic airway obstruction in adulthood. Several different mechanisms have been identified by which respiratory viruses provoke asthma. No one single mechanism, however, adequately explains virus-induced asthma. Nonetheless, a common thread to these various proposed mechanisms is the ability of respiratory viruses to cause airway inflammation, either directly, through cytopathic effects, or indirectly, by increasing the inflammatory processes of respiratory cells. The consequence of these effects causes increased airway responsiveness and asthma.     

Exacerbations of asthma in adults during experimental rhinovirus infection

To determine the incidence of wheezing in adult asthmatics with rhinovirus infection, we exposed 21 asthmatic volunteers to 1 of 2 rhinovirus serotypes. Symptoms, spirometry, and histamine inhalation challenge were assessed prior to, daily during, and 3 wk after the rhinovirus infection. Four volunteers had fiberoptic bronchoscopy performed on the fourth study day. Nineteen volunteers became infected with rhinovirus; 17 of 19 had typical coryzal symptoms. Volunteers did not have significant changes in spirometry or histamine sensitivity during rhinovirus infection when taken as a group or when categorized by severity of asthma or severity of the clinical illness. A subgroup of 4 volunteers was identified that had a 10% or greater decrease in FEV1 and a parallel increase in histamine sensitivity during rhinovirus infection; these 4 volunteers were not otherwise distinguishable from the group as a whole. Rhinovirus was recovered from bronchoscopy specimens of 1 of the 4 infected volunteers bronchoscoped. Thus, exacerbations of wheezing occurred in the minority of experimental rhinovirus infections in adult asthmatics, suggesting that other viral pathogens may play a more important role in precipitating asthma attacks.     

Reduced granulocyte response to isoproterenol, histamine, and prostaglandin E1 after in vitro incubation with Rhinovirus 16

Rhinovirus respiratory infections have been frequently associated with the precipitation of an asthma attack. As an explanation for virus-provoked asthma, it has been proposed that viruses or their products may alter beta-adrenergic responsiveness. Isolated human granulocytes have provided an in vitro study model for this problem. Granulocyte release of the lysosomal enzyme beta-glucuronidase (BG) occurred after incubation with complement-activated zymosan particles, and this release was inhibited by isoproterenol (ISO), histamine (HIS) acting via its H2 receptor, and prostaglandin E1 (PGE1). In asthma, the granulocyte response to HIS and ISO was impaired, and the ISO impairment was accentuated during virus-provoked asthma. After an in vitro incubation of polymorphonuclear leukocytes (PMN) with rhinovirus 16, the granulocyte response to ISO, HIS, and PGE1 was significantly reduced. This change in agonist response was proportional to the virus dosage, maximal at 37 degrees C and after a 60-min incubation period, and occurred with heat or UV-inactivated virus. It is possible that impaired beta-adrenergic responsiveness may also develop in other tissues, such as the airway smooth muscle, and thus explain, in part, wheezing during viral respiratory infections.     

A parental history of asthma is a risk factor for wheezing and nonwheezing respiratory illnesses in infants younger than 18 months of age

The relationship between respiratory infection and allergy as risk factors for the development of wheezing illnesses in infants has been in dispute. We hypothesized that a parental history of allergic diseases would be associated with an increased rate of respiratory infections as well as an increased rate of wheezing during infectious episodes. We prospectively evaluated 1,193 infants from birth to 18 mo of age, using bi-weekly telephone surveillance to document all respiratory events. The overall rate of respiratory illness (all RI) increased to a maximum of 10.6 illnesses/infant/year in the 7- to 9-mo age group and then leveled off in the older infants. Multivariable models adjusting for demographic variables, breast feeding, month of illness, number of siblings, and attendance at day care showed an increase in the rate of all RI in infants older than 7 mo of age who had a parental history of asthma (OR = 1.24, CI = 1.09 to 1.41) or a parental history of atopy (OR = 1.14, CI = 1.03 to 1.26). The rate of lower respiratory illnesses accompanied by wheezing was related only to a parental history of asthma (OR = 2.06, CI = 1.36 to 3.11). We conclude that all RI, most of which represent viral infections, are increased in otherwise normal infants with a parental history of asthma or atopy, whereas wheezing is related only to a parental history of asthma.     

Bronchiolitis to asthma: a review and call for studies of gene-virus interactions in asthma causation

Viral infections are important causes of asthma exacerbations in children, and lower respiratory tract infections (LRTIs), caused by viruses such as respiratory syncytial virus (RSV) and rhinovirus (RV), are a leading cause of bronchiolitis in infants. Infants hospitalized with bronchiolitis are at significantly increased risk for both recurrent wheezing and childhood asthma. To date, studies addressing the incidence of asthma after bronchiolitis severe enough to warrant hospitalization have focused almost exclusively on RSV, but a number of recent studies suggest that other respiratory pathogens, including RV, may contribute as well. It is not known whether viral bronchiolitis directly contributes to asthma causation or simply identifies infants at risk for subsequent wheezing, as from an atopic predisposition or preexisting abnormal lung function. Alternatively, the properties of the infecting virus may be important. Thus, many possible determinants exist that may contribute to the severity of bronchiolitis and the subsequent development of asthma. One such determinant is the potential involvement of genetic susceptibility loci to asthma after viral bronchiolitis, a critical area that is just beginning to be evaluated. By clarifying the roles of both host- (genetic) and virus- (environment) specific factors that contribute to the frequency and severity of viral LRTI, it may be possible to determine if severe LRTIs cause asthma, or if asthma susceptibility predisposes patients to severe LRTI in response to viral infection. Characterizing these relationships offers the potential of identifying at-risk hosts in whom preventing or delaying infection could alter the phenotypic expression of asthma.     

Detection and characterization of respiratory viruses causing acute respiratory illness and asthma exacerbation in children during three different seasons (2011–2014) in Mexico City

Background

Viral infections play a significant role in causing acute respiratory infections (ARIs) and exacerbations of chronic diseases. Acute respiratory infections are now the leading cause of mortality in children worldwide, especially in developing countries. Recently, human rhinovirus (HRV) infection has been emerged as an important cause of pneumonia and asthma exacerbation.

Objectives

To determine the role of several viral agents principally, respiratory syncytial virus, and HRV in children with ARIs and their relationship with asthma exacerbation and pneumonia.

Methods

Between October 2011 and March 2014, 432 nasopharyngeal samples of children <15 years of age with ARI hospitalized at a referral hospital for respiratory diseases were tested for the presence of respiratory viruses using a multiplex RT-qPCR. Clinical, epidemiological, and demographic data were collected and associated with symptomatology and viral infections.

Results

Viral infections were detected in at least 59·7% of the enrolled patients, with HRV (26·6%) being the most frequently detected. HRV infections were associated with clinical features of asthma and difficulty in breathing such as wheezing (P = 0·0003), supraesternal (P = 0·046), and xiphoid retraction (P = 0·030). HRV subtype C (HRV-C) infections were associated with asthma (P = 0·02).

Conclusions

Human rhinovirus was the virus most commonly detected in pediatric patients with ARI. There is also an association of HRV-C infection with asthma exacerbation, emphasizing the relevance of this virus in severe pediatric respiratory disease.     

Viruses in asthma exacerbations

PURPOSE OF REVIEW: Respiratory viruses are well recognized as major triggers of acute exacerbations of asthma in children and adults, resulting in frequent outpatients visits and hospitalizations. Clinical and epidemiologic evidence supports this association. The application of molecular diagnostic methods has improved understanding of viral epidemiology and the pathophysiological mechanisms involved in viral induced acute asthma. This article reviews publications since October 2002 for an update of the role of viruses in exacerbations of asthma. RECENT FINDINGS: Respiratory viruses are present in most patients hospitalized for life-threatening asthma and acute non life-threatening asthma. Rhinovirus is the most common, but coinfection with other viruses may be important. Patients with asthma are not more susceptible to upper respiratory tract rhinovirus infections than healthy people but suffer from more severe consequences of the lower respiratory tract infection. Recent epidemiologic studies suggest that viruses provoke asthma attacks by additive or synergistic interactions with allergen exposure or with air pollution. An impaired antiviral immunity to rhinovirus may lead to impaired viral clearance and hence prolonged symptoms. Respiratory viral infections cause asthmatic exacerbations by triggering recruitment of Th2-type cells into the lungs. There is no specific antiviral strategy for prevention of respiratory-triggered asthma exacerbations, although clinical trials of potential antiviral agents are ongoing. Indirect prevention strategies focus on the reduction of overall airway inflammation to reduce the severity of the host response to respiratory viral infections. SUMMARY: Respiratory viral infections are a major cause of morbidity and mortality in asthma. There is a lack of specific antiviral strategies in the prevention or reduction of viral-triggered asthma exacerbations. Recent advances in understanding of the epidemiology and immunopathogenesis of respiratory viral infection in asthma provide opportunities or identification of specific targets for antiviral agents and strategies for management and prevention.     

Respiratory viral infections after bone marrow/peripheral stem-cell transplantation: the Christie hospital experience

Respiratory virus infections are an important cause of morbidity and mortality in bone marrow transplant patients. A retrospective study was performed on the bone marrow transplant unit at the Christie Hospital Manchester. The aim of this study was to determine the frequency, clinical presentation, laboratory diagnosis, types of intervention (eg antiviral agents used) and the outcome of such infections in this cohort of transplant recipients. Data were collected from a total of 626 adult patients and showed 27 patients with 29 confirmed episodes of viral respiratory tract infections. The viruses present were rhinovirus (40%), respiratory syncytial virus (RSV) (22.2%), influenza A (18.5%), parainfluenza (PIV) (14.8%) and enteroviruses (7.4%). The overall frequency of documented respiratory virus infections was 4.3% during the 5-year period of the study. The prevalence of respiratory viral infections was 7.8% among allogeneic and 2.3% among autologous transplant recipients. The frequency of lower respiratory tract infection (LRTI) was 3.0% among allogeneic and 1.3% among autologous transplant recipients. Eight patients died (seven had allogeneic transplants). Three of these deaths were directly attributable to a respiratory viral infection (two rhinoviruses; one PIV 3). This study further supports the role played by human respiratory viruses in transplant-associated morbidity and mortality, and particularly highlights the significance of rhinovirus infections.     

The role of viruses in development or exacerbation of atopic asthma

Respiratory viral infections in early childhood have been linked to the development of persistent wheezing and asthma. Epidemiologic data indicate that, for the majority of children, virus-induced wheezing is a self-limited condition, with no long-term consequences. For a substantial minority, however, virus-induced wheezing is associated with persistent asthma and the potential for enhanced allergic sensitization. For the most part, this subset of patients is genetically predisposed; they are atopic children in whom respiratory viral infections trigger the early development of asthma by mechanisms that have not been fully elucidated. Both inflammatory and noninflammatory mechanisms may be involved. It does not appear that viral infection per se in early life is responsible for the induction of atopic asthma. Data from animal models provide support for the concept that enhanced allergic sensitization caused by increased uptake of allergen during infection may play a critical role, as well as T-cell-mediated immune responses to viral infection, which may favor eosinophilic inflammatory responses and the development of altered airway function to inhaled methacholine. Recent advances in our understanding of the interactions between respiratory viruses and the development of reactive airway disease offer new possibilities for preventive treatment in children at risk for developing persistent wheezing and asthma exacerbation as a result of viral infection.     

Influenza and rhinovirus infections among health-care workers

BACKGROUND AND OBJECTIVE: Health-care workers (HCWs) are at higher risk of acquisition and transmission of respiratory virus infections. Nosocomial transmission of influenza has been documented but whether this is so for other respiratory viruses has not been assessed. METHODS: Epidemiological, clinical and viral laboratory surveillance was carried out on HCWs presenting with acute respiratory infection in a university hospital. RESULTS: Over a 2-year period, 203 subjects were recruited: rhinovirus was the most frequently detected virus (37.7% in flu negative samples) and influenza A/B was positive in only 12.3% of subjects. Only 19.7% of HCWs were immunized against influenza. High detection of rhinovirus occurred even during the peak of the influenza season and half of the infected subjects reported an influenza-like illness. CONCLUSION: Rhinovirus infection occurred frequently in this study population and probably contributes to influenza misdiagnosis. Educational interventions about different viruses causing respiratory symptoms and an increase in standards of infection control besides influenza immunization among HCWs is needed.     

Increased risk of rhinovirus infection in children during the coronavirus disease‐19 pandemic

BackgroundCoronavirus disease (COVID‐19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), was first detected in Japan in January 2020 and has spread throughout the country. Previous studies have reported that viral interference among influenza virus, rhinovirus, and other respiratory viruses can affect viral infections at the host and population level.MethodsTo investigate the impact of COVID‐19 on influenza and other respiratory virus infections, we analyzed clinical specimens collected from 2244 patients in Japan with respiratory diseases between January 2018 and September 2020.ResultsThe frequency of influenza and other respiratory viruses (coxsackievirus A and B; echovirus; enterovirus; human coronavirus 229E, HKU1, NL63, and OC43; human metapneumovirus; human parainfluenza virus 1, 2, 3, and 4; human parechovirus; human respiratory syncytial virus; human adenovirus; human bocavirus; human parvovirus B19; herpes simplex virus type 1; and varicella‐zoster virus) was appreciably reduced among all patients during the COVID‐19 pandemic except for that of rhinovirus in children younger than 10 years, which was appreciably increased. COVID‐19 has not spread among this age group, suggesting an increased risk of rhinovirus infection in children.ConclusionsRhinovirus infections should be continuously monitored to understand their increased risk during the COVID‐19 pandemic and viral interference with SARS‐CoV‐2.     

The immunology of virus infection in asthma.

The respiratory tract is commonly infected by a range of viruses with overlapping pathologies. The majority of episodic exacerbations of asthma are associated with viral infection, in particular with rhinovirus infections. Experimental rhinovirus infection in human volunteers provides a useful model of natural virus-induced asthma. The asthmatic airway is characterized by an infiltrate of eosinophils and T-lymphocytes expressing the type 2 cytokines interleukin (IL)-4, IL-5 and IL-13. An effective antiviral immune response requires early viral clearance and appropriate termination of the immune response to minimize associated immunopathology and tissue damage. The antiviral immune response is made up of innate (nonspecific) and specific components, and requires the coordinated actions of many different cell types including neutrophils, macrophages, eosinophils, dendritic cells, epithelial cells, mast cells, natural killer cells and B- and T-lymphocytes. Coordination of this response involves numerous cytokines and chemokines. T-lymphocytes expressing type 1 cytokines including interferon-gamma play a key role. Pre-existing asthmatic inflammation in the lower airway may modify the immune response to viral infection by altering the balance of T-cell cytokine expression from type 1 towards a type 2 in what is always a mixed response. The consequence is delayed viral clearance, persistent virus-induced inflammation and amplification of the allergic inflammation.     

Infection, eosinophilia and childhood asthma

There is a growing list of viruses and bacteria associated with wheezing illness and asthma. It is well known that a few of these pathogens are strongly associated with wheezing illness and asthma exacerbations. What is not known is if early childhood infections with these pathogens cause asthma, and, if so, exactly what are the pathophysiologic mechanisms behind its development. The current consensus is respiratory infection works together with allergy to produce the immune and physiologic conditions necessary for asthma diasthesis. One link between respiratory infection and asthma may be the eosinophil, a cell that plays prominently in asthma and allergy, but can also be found in the body in response to infection. In turn, the eosinophil and its associated products may be novel therapeutic targets, or at the very least used to elucidate the complex pathophysiologic pathways of asthma and other respiratory illnesses. Together or separately, they can also be used for diagnosis, treatment and monitoring. The optimal care of a patient must take into consideration not only symptoms, but also the underlying disease mechanisms.     

Symptomatic Improvement Following Emergency Department Management of Asthma: A Pilot Study of Intramuscular Dexamethasone Versus Oral Prednisone

Systemic corticosteroid therapy is an established adjunct to beta-adrenergic medications in acute exacerbations of asthma. To date, no study has defined the role of long-acting intramuscular preparations of corticosteroids in pediatric patients with asthma. A pilot study was conducted to prospectively compare symptomatic improvement following a single injection of intramuscular dexamethasone (IMD) to a 3-day regimen of oral prednisone (OP) for children with mild to moderate wheezing episodes that are responsive to nebulized medications in the Pediatric Emergency Department (PED). The following children presenting with acute exacerbations of asthma to the PED were eligible for enrollment: age 3-16 years; more than two prior wheezing episodes; mild to moderate wheezing; and oxygen saturation 95% or more in room air. The study patients were randomly assigned to receive either IMD (n = 21) or OP (n = 21) in addition to a standardized treatment regimen of nebulized albuterol. All of the children were clinically rated for wheezing severity by the Pulmonary Index (PI) score at regular intervals during the study. Discharge home was based on clinical improvement during treatment in the PED; patients who were admitted to the hospital were removed from the study. Follow-up was conducted the fifth day after discharge from the ED either by clinic visit or by telephone. Patients were assessed for symptomatic improvement and relapse or clinical deterioration during the study period by a clinician blinded to group assignment. Forty-two children participated in this pilot study. There were no significant differences between the IMD and OP groups for gender or age. Mean ages were: 82 months (SD 46 months), IMD group; 63 months (SD 36 months), OP group. Clinical progress (based on PI) with treatment in the PED was the same in both groups: pretreatment median, PI = 6; PED discharge median, PI = 2. None of the study patients were hospitalized during the follow-up period, and all reported symptomatic improvement since initial treatment. The data of this pilot study suggest that IMD may be a feasible alternative to OP for treatment of acute wheezing episodes in children with asthma. IMD provides sufficient treatment to prevent clinical deterioration within 5 days after initial therapy for mild to moderate pediatric exacerbations of asthma that are responsive to nebulized medications.