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

Virological Profile of Asthma Exacerbation in Children: A Hospital-Based Retrospective Study

Introduction Viruses are the most common triggering factors for asthma exacerbation during the autumn and winter seasons. Viruses, such as influenza A and rhinovirus, play a major role in the occurrence of severe exacerbation of asthma. This association between viral infection and asthma exacerbation in children is a result of the antiviral response of the immune system and various anti-inflammatory phenomena. In this work, we aimed to identify the virological profile of asthma exacerbation in children and analyze the correlation between viral infection type and the severity of exacerbation. Materials and methods This retrospective study was conducted from January 2016 to January 2024. The study included children hospitalized for asthma exacerbation associated with signs of viral-like respiratory infection with positive virological testing by multiplex real-time polymerase chain reaction or rapid test in the case of influenza A or respiratory syncytial virus (RSV). Data analysis was performed with Microsoft Excel and SPSS software using a previously established data collection sheet Results Thirty cases were collected for the study period. The mean age of the patients was 4 years and 8 months, with a male-to-female ratio of 3.3. Eighteen patients were known to have asthma, of which nine had uncontrolled asthma, and exacerbation was inaugural in 12 patients. Viral shedding was found in 14 patients. A viral agent was found in all patients, with coinfection of two or more viruses in three patients. The viruses found were influenza A (18 cases), coupled rhinovirus/enterovirus (eight cases), RSV (eight cases), human metapneumovirus (three patients), and parainfluenza type IV in only one inaugural patient. Asthma exacerbation was severe in 20 patients, moderate in eight patients, and two patients had severe acute asthma requiring intensive care management. We noted a higher frequency of severe exacerbation among those with an influenza A viral infection. All patients with RSV infection exhibited moderate exacerbation. No other significant correlation between asthma severity and other types of viruses was found. Conclusions Our results demonstrate the major role played by viruses in triggering asthma exacerbation, primarily influenza virus, followed by enterovirus, rhinovirus, RSV, and metapneumovirus. Larger-scale studies should be carried out to establish a more complete virological profile and further investigate the viral factor in the management of asthma in children.

Pediatric asthma exacerbation and COVID-19 pandemic: Impacts, challenges, and future considerations

OBJECTIVE

Asthma, a common disease among children and adolescents, poses a great health risk when ignored; therefore, a thorough follow-up to prevent exacerbations is emphasized. The aim of the present study is to investigate asthma exacerbation in children during the Coronavirus disease 2019 (COVID-19) era.

DATA SOURCES

This narrative review has been done by searching the PubMed and Embase databases using Asthma, COVID-19, Pandemic, and Symptom flare up as keywords.

STUDY SELECTIONS

Studies related to asthma exacerbation in COVID-19 pandemic were included.

RESULTS

Based on studies, controlled or mild to moderate asthma has not been considered a risk factor for COVID-19 severity and has not affected hospitalization, intensive care unit (ICU) admission, and mortality. Surprisingly, emergent and non-emergent visits and asthmatic attacks decreased during the pandemic. The three main reasons for decreased incidence and exacerbation of asthma episodes in the COVID-19 era included reduced exposure to environmental allergens, increasing the acceptance of treatment by pediatrics and caregivers, and decreased risk of other respiratory viral infections. Based on the available studies, COVID-19 vaccination had no serious side effects, except in cases of uncontrolled severe asthma, and can be injected in these children. Also, there was no conclusive evidence of asthma exacerbation after the injection of COVID-19 vaccines.

CONCLUSION

Further studies are recommended to follow the pattern of asthma in the post-pandemic situation and to become prepared for similar future conditions.

Comparison of the prevalence and risk factors of chronic allergic diseases before and after COVID-19: using raw data from the Korea National Health and Nutrition Examination Survey in 2019 and 2021

OBJECTIVE

This study aimed to analyze the prevalence of chronic allergic diseases before and after the COVID-19 pandemic using data from the Korea National Health and Nutrition Examination Survey in 2019 and 2021.

DATA SOURCES

A representative sample of Korean adults (n = 10,346) aged 19-85 years who completed the survey in 2019 and 2021 was analyzed.

STUDY SELECTION

General and health-related characteristics, as well as the prevalence and diagnosis of asthma, atopic dermatitis, and allergic rhinitis, were compared between the two years. Sub-analyses by gender and age were also conducted.

RESULTS

Statistically significant differences were found in marital status, subjective health perception, sleep quality, and walking status between 2019 and 2021. However, there were no statistically significant differences in the prevalence and diagnosis of asthma, atopic dermatitis, and allergic rhinitis. In a sub-analysis by gender and age, the prevalence of asthma in teenagers showed a statistically significant increase in 2021 compared to 2019, while it decreased significantly in the 30s group.

CONCLUSION

This study found no significant changes in the prevalence and diagnosis of chronic allergic diseases before and after the COVID-19 pandemic in Korea. However, changes in lifestyle factors, such as physical activity and sleep quality, were observed. Further research on the relationship between COVID-19 and chronic allergic diseases is necessary, and healthcare providers should consider lifestyle changes in their treatment of chronic allergic disease patients during the pandemic.

Lockdown Fatigue in Pediatric Respiratory Patients: Lessons from the First COVID-19 Year

Lockdown policies have been implemented worldwide to limit the spread of COVID-19. “Lockdown fatigue” is a state of exhaustion related to the accumulating effects of repeated lockdowns. The aim of the current study was to examine the effects of repeated lockdowns on children with respiratory disorders. Data on children aged 0−18 years old with respiratory disorders were collected by an electronic survey during the third lockdown in Israel. The retrieved information included demographics and baseline medical status, respiratory clinical status during the third lockdown compared to pre-lockdown periods, lockdown adherence, lifestyle modifications and caregiver emotional status. The results were compared to those of a similar questionnaire distributed during the first lockdown. A total of 234 patients (62% males, 37% females, mean age 6.8 years (confidence interval 6.1−7.5)) were enrolled. Respiratory symptoms and exacerbation frequency were reduced in 76 (35.5%) and 58 (27.4%) patients, respectively, compared to the pre-lockdown period and similar to the first lockdown (p = 0.840 and p = 0.063, respectively). However, compared to the first lockdown, the third lockdown was associated with greater use of reliever medications (p = 0.006), less use of inhaled corticosteroids as routine treatment (p = 0.027), and more pediatric emergency room visits and hospitalizations (p = 0.001 and p < 0.001, respectively). The results also showed an increase in sedentary lifestyle (e.g., reduced physical activity (p = 0.025), less healthy eating habits (p = 0.001)) and reduced adherence to lockdown policies (p < 0.001). These data show that the continuing stability of clinical improvement during lockdown was accompanied by deleterious sequelae that potentially indicate “lockdown fatigue” among children with respiratory disorders.

Real-time effects of COVID-19 pandemic lockdown on pediatric respiratory patients

OBJECTIVE

A national lockdown was implemented in Israel to slow the viral spread of COVID-19. We assessed the real-time effects of the lockdown on disease expression and lifestyle modifications in pediatric patients with chronic respiratory disorders.

METHODS

An anonymous electronic questionnaire was distributed during lockdown (March-May 2020) to caregivers of patients with chronic respiratory disorders. The primary outcome was change in disease expression and the secondary outcomes were changes in lifestyle and caregivers' emotional status.

RESULTS

The clinical status of one-third of the 445 participating patients (age 0-18 years) reportedly improved, including decreased respiratory symptoms (n = 133, 33%), exacerbation frequency (n = 147, 35%), and use of reliever medications (n = 101, 27.4%). The condition of ~10% of the patients worsened. Clinical improvement was noted mostly in young patients <5 years (p = .001), asthmatic patients (p = .033), and patients with multiple underlying respiratory disorders (p = .015). Patients whose condition significantly worsened were more likely to be >5 years (p < .001), had increased screen time, decreased physical activity, and shorter sleep duration compared to their younger counterparts (p = .008, <.001, and .001, respectively). Caregivers' reports (n = 236 [58%]) of their own anxiety levels and perceptions of the patients' elevated health risk were increased, regardless of the children's actual clinical status.

CONCLUSION

COVID-19 lockdown was associated with clinical improvement/stability for most of the surveyed children; however, their caregivers' anxiety level was heightened. An increased sedentary lifestyle was reported mostly in older children.

Mycoplasma pneumoniae infection and risk of childhood asthma: A systematic review and meta-analysis

The etiology of childhood asthma is multifactorial, atypical bacterial pathogens, including Mycoplasma pneumoniae, have been proposed as possible risk factors or contributors. This review aims to assess the possible association between M. pneumoniae infection and childhood asthma. We searched major international literature databases (up to January 10, 2021) to identify relevant studies. We used a random-effects meta-analysis (REM) model to generate the pooled odds ratio (OR) and 95% confidence intervals (CIs). Several subgroups analyses were performed concerning the IgG, IgM, and DNA detection of M. pneumoniae infection. We included 22 eligible studies; these studies involved a total of 5064 children. We found that there was a statistically significant association between M. pneumoniae infection, as determined by IgM serology (OR, 3.13; 95% CI, 1.78-5.48), and DNA detection (OR, 1.57; 95% CI, 1.25-1.97) with increased risk of any type of childhood asthma. Moreover, children with acute asthma had significantly higher seropositivity for anti- M. pneumoniae IgM antibodies (OR, 4.43; 95% CI, 2.80-7.02) than children with stable asthma. Although our findings indicate a positive association between M. pneumoniae infection and childhood asthma, well-designed and -controlled studies are need in the future to rigorously test this association and identify the underlying mechanisms.

The Impact of the SARS-CoV-2 Pandemic on the Emergency Department and Management of the Pediatric Asthmatic Patient

INTRODUCTION

Asthma exacerbation is among the commonest causes for pediatric emergency room visits, and respiratory viruses are frequent triggers of such exacerbations. Few studies have evaluated the consequences of the novel human coronavirus that causes the illness currently known as COVID-19, in the pediatric population.

PURPOSE

The objective of this study was to analyze the impact of the COVID-19 pandemic and lockdown measures on the emergency department in the pediatric asthmatic patient.

PATIENTS AND METHODS

This retrospective observational study evaluated pediatric patients treated at the Pediatric Emergency Service for wheezing episodes. Changes in the number and characteristics of these patients over the same period of 2019 as compared to 2020 during the month following the alarm declaration (March 14 to April 15) were evaluated.

RESULTS

In total, data of 30 asthma patients managed in the period after the declaration of the coronavirus pandemic and of 158 asthma patients managed in the pre-COVID-19 period were included. In 2020, patient visits decreased by 82% in 2019. No statistically significant differences among age, sex, oxygen saturation, fever status, or number of severe bronchospasm episodes were found. Nebulized medication usage was reduced significantly since the alarm declaration. No significant increase in requests for complementary testing in the COVID-19 period was found. No patient requiring hospital admission was found to be PCR SARS-CoV-2 positive. Median time spent in the emergency department decreased from 180 minutes in 2019 to 85 minutes in the COVID-19 era.

CONCLUSION

The COVID-19 pandemic and ensuing lockdown measures have led to an extraordinary reduction in emergency visits to the pediatric service. The ongoing pandemic has also led to improvements in the approach to asthma exacerbations and wheezing, to reduce the risk of exposure to the virus, such as increased use of pressurized metered dose inhaler and decreased time in the Emergency Department.

Pediatric asthma and COVID-19: The known, the unknown, and the controversial

The novel coronavirus disease-2019 (COVID-19), caused by the pathogen severe acute respiratory syndrome-CoV-2, is causing a global pandemic, with over 26.9 million cases and 880,000 deaths as of September 6, 2020. While there has been speculation and observational research about the impact of COVID-19 on asthma, much remains unknown. The goal of this article is to provide a scoping review on pediatric asthma and COVID-19 and summarize what we do and do not know from the first wave of the pandemic.

Childhood asthma heterogeneity at the era of precision medicine: Modulating the immune response or the microbiota for the management of asthma attack

Exacerbations are a main characteristic of asthma. In childhood, the risk is increasing with severity. Exacerbations are a strong phenotypic marker, particularly of severe and therapy-resistant asthma. These early-life events may influence the evolution and be involved in lung function decline. In children, asthma attacks are facilitated by exposure to allergens and pollutants, but are mainly triggered by microbial agents. Multiple studies have assessed immune responses to viruses, and to a lesser extend bacteria, during asthma exacerbation. Research has identified impairment of innate immune responses in children, related to altered pathogen recognition, interferon release, or anti-viral response. Influence of this host-microbiota dialog on the adaptive immune response may be crucial, leading to the development of biased T helper (Th)2 inflammation. These dynamic interactions may impact the presentations of asthma attacks, and have long-term consequences. The aim of this review is to synthesize studies exploring immune mechanisms impairment against viruses and bacteria promoting asthma attacks in children. The potential influence of the nature of infectious agents and/or preexisting microbiota on the development of exacerbation is also addressed. We then discuss our understanding of how these diverse host-microbiota interactions in children may account for the heterogeneity of endotypes and clinical presentations. Finally, improving the knowledge of the pathophysiological processes induced by infections has led to offer new opportunities for the development of preventive or curative therapeutics for acute asthma. A better definition of asthma endotypes associated with precision medicine might lead to substantial progress in the management of severe childhood asthma.

Prevalence of viral respiratory infections amongst asthmatics: Results of a meta-regression analysis

Viral respiratory infections (VRI) can act as triggers for acute asthma exacerbations and contribute significantly to asthma-related healthcare costs. Knowing the patterns of viruses amongst asthmatics can be useful in treating and preventing these exacerbations and help decrease the burden they impose on patients and healthcare systems. We aimed to quantify the viral prevalence in asthmatics presenting with exacerbations and identify influencing factors. A meta-analysis with a systematic search was conducted. Random-effect analysis was performed to quantify prevalence of viruses. A meta-regression was conducted to explain sources of heterogeneity and identify confounding factors. A VRI was detected in 52%-65% of the cases, and the detection rate was higher in children compared to adults. Rhinovirus was most often detected [51-71%], followed by respiratory syncytial virus [8-18%], influenza virus [7-15%], human parainfluenza virus [4-11%] and metapneumovirus virus [3-9%]. Meta-regression showed that the variables age and hemisphere contributed to the heterogeneity observed and were significantly associated with the detection of viruses in asthmatics. The climate variable reached significance for RSV and indicated a higher detection rate of viruses in asthmatics living in temperate compared to tropical regions. Besides age, geographic location and related variables significantly influence to what extent respiratory viruses are detected amongst asthmatics with exacerbations. Our results indicate that health authorities should adopt region- and population specific prevention and treatment strategies. Prevention and detection of viral respiratory infections in asthmatics could reduce asthma related disease burden and decrease antibiotic misuse.

Respiratory pathogens and clinical outcomes in children with an asthma exacerbation: A systematic review

BACKGROUND

In asthmatic children, respiratory pathogens are identified in 60%-80% of asthma exacerbations, contributing to a significant burden of illness. The role of pathogens in the clinical evolution of exacerbations is unknown.

OBJECTIVE

We systematically reviewed the association between the presence of pathogens and clinical outcomes in children with an asthma exacerbation.

METHOD

PubMed, EMBASE, BIOSIS, and the Cochrane Central Register of Controlled Trials were searched up to October 2016 for studies reporting on respiratory pathogen exposure and clinical outcome. The Risk of Bias in Non-Randomized Studies of Interventions tool was used for quality assessment.

RESULTS

Twenty-eight observational studies (N = 4,224 children) reported on 112 different associations between exposure to any pathogen (n = 45), human rhinovirus (HRV; n = 34), atypical bacteria (n = 21), specific virus (n = 11), or bacteria (n = 1) and outcomes of exacerbation severity (n = 26), health care use (n = 38), treatment response (n = 19), and morbidity (n = 29). Restricting the analysis only to comparisons with a low to moderate risk of bias, we observed an association between HRV and higher exacerbation severity on presentation (regression p = .016) and between the presence of any pathogen and emergency department treatment failure (odds ratio [OR] = 1.57; 95% CI 1.04% to 2.37%). High-quality evidence for effect on morbidity or health care use is lacking.

CONCLUSIONS

Further research on the role of pathogen-treatment interaction and outcomes is required to inform the need for point-of-care, real-time testing for pathogens. Studies with a sufficiently large sample size that address selection bias, correctly adjust for confounding, and rigorously report core patient-centred outcomes are necessary to improve knowledge.

Molecular detection of respiratory pathogens and typing of human rhinovirus of adults hospitalized for exacerbation of asthma and chronic obstructive pulmonary disease

BACKGROUND

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) and asthma are associated with a variety of precipitating factors including infection. This study assessed the infective viral etiologies by real-time multiplex polymerase chain reaction of patients hospitalized with AECOPD and asthma exacerbations. In addition, infective etiologies were assessed for association with the clinical outcome of the patients.

METHODS

Adults admitted with AECOPD and asthma exacerbations between August 2016 and July 2017 were recruited. Nasopharyngeal aspirate (NPA) samples were obtained from the patients within 1-2 days of admission and subjected to pathogen detection and human rhinovirus (HRV) typing.

RESULTS

Altogether 402 patients with AECOPD, 80 stable COPD, 100 asthma exacerbation and 21 stable asthma subjects were recruited. Among those admitted for AECOPD and asthma exacerbations, 141(35.1%) and 45(45.0%) respectively had pathogens identified in the NPA specimens. The commonest virus identified was influenza A followed by HRV. HRV typing identified HRV-A and HRV-C as the more common HRV with a wide variety of genotypes. Identification of pathogens in NPA or HRV typing otherwise did not affect clinical outcomes including the hospital length of stay, readmission rates and mortality except that identification of pathogens in asthma exacerbation was associated with a lower rate of readmissions at 30 and 60 days.

CONCLUSIONS

Many respiratory viruses were associated with AECOPD and asthma exacerbation. HRV-A and HRV-C were the more common HRV associated with exacerbations. Identification of pathogens in NPA was associated with less readmissions for asthma patients at 30 and 60 days.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02866357 .

Influenza burden, prevention, and treatment in asthma-A scoping review by the EAACI Influenza in asthma task force

To address uncertainties in the prevention and management of influenza in people with asthma, we performed a scoping review of the published literature on influenza burden; current vaccine recommendations; vaccination coverage; immunogenicity, efficacy, effectiveness, and safety of influenza vaccines; and the benefits of antiviral drugs in people with asthma. We found significant variation in the reported rates of influenza detection in individuals with acute asthma exacerbations making it unclear to what degree influenza causes exacerbations of underlying asthma. The strongest evidence of an association was seen in studies of children. Countries in the European Union currently recommend influenza vaccination of adults with asthma; however, coverage varied between regions. Coverage was lower among children with asthma. Limited data suggest that good seroprotection and seroconversion can be achieved in both children and adults with asthma and that vaccination confers a degree of protection against influenza illness and asthma-related morbidity to children with asthma. There were insufficient data to determine efficacy in adults. Overall, influenza vaccines appeared to be safe for people with asthma. We identify knowledge gaps and make recommendations on future research needs in relation to influenza in patients with asthma.

Presence of atopy increases the risk of asthma relapse

OBJECTIVES

To describe the point prevalence of respiratory viruses/atypical bacteria using PCR and evaluate the impact of respiratory viruses/atypical bacteria and atopy on acute severity and clinical recovery in children with hospitalised and non-hospitalised asthma exacerbations.

DESIGN

This was a prospective study performed during 2009-2011.

SETTING

The study was performed in the emergency departments of two hospitals.

PATIENTS

244 children aged 2-16 years presenting with acute asthma to the emergency departments were recruited. A nasopharyngeal aspirate and allergen skin prick test were performed.

MAIN OUTCOME MEASURES

The outcomes were divided into (1) acute severity outcomes (Australian National Asthma Council assessment, hospitalisation, Functional Severity Scale, Acute Asthma Score, asthma quality of life questionnaires for parents (PACQLQ) on presentation, asthma diary scores (ADS) on presentation and length of hospitalisation) and (2) recovery outcomes (PACQLQ for 21 days, ADS for 14 days and representation for asthma for 21 days).

RESULTS

PCR for viruses/atypical bacteria was positive in 81.7% of children (75.1% human rhinovirus, codetection in 14.2%). Mycoplasma pneumoniae and Chlamydophila pneumoniae were rarely detected. The presence of micro-organisms had little impact on acute asthma or recovery outcomes. Children with atopy were significantly more likely to relapse and represent for medical care by day 14 (OR 1.11, 95% CI 1.00 to 1.23).

CONCLUSIONS

The presence of any viruses is associated with asthma exacerbations but does not appear to influence asthma recovery. In contrast, atopy is associated with asthma relapse. M. pneumoniae and C. pneumoniae are rare triggers of acute asthma in young children.

Interventions for autumn exacerbations of asthma in children

BACKGROUND

Asthma exacerbations in school-aged children peak in autumn, shortly after children return to school following the summer holiday. This might reflect a combination of risk factors, including poor treatment adherence, increased allergen and viral exposure, and altered immune tolerance. Since this peak is predictable, interventions targeting modifiable risk factors might reduce exacerbation-associated morbidity and strain upon health resources. The peak occurs in September in the Northern Hemisphere and in February in the Southern Hemisphere.

OBJECTIVES

To assess the effects of pharmacotherapy and behavioural interventions enacted in anticipation of school return during autumn that are designed to reduce asthma exacerbations in children during this period.

SEARCH METHODS

We searched the Cochrane Airways Group Trials Register, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform, reference lists of primary studies and existing reviews, and manufacturers' trial registries (Merck, Novartis and Ono Parmaceuticals). We searched databases from their inception to 1 December 2017, and imposed no restriction on language of publication.

SELECTION CRITERIA

We included all randomised controlled trials comparing interventions aimed specifically at reducing autumn exacerbations with usual care, (no systematic change in management in preparation for school return). We included studies providing data on children aged 18 years or younger.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Two review authors independently screened records identified by the search and then extracted data and assessed bias for trials meeting the inclusion criteria. A third review author checked for accuracy and mediated consensus on disagreements. The primary outcome was proportion of children experiencing one or more asthma exacerbations requiring hospitalisation or oral corticosteroids during the autumn period.

MAIN RESULTS

Our searches returned 546 trials, of which five met our inclusion criteria. These studies randomised 14,252 children to receive either an intervention or usual care. All studies were conducted in the Northern Hemisphere. Three interventions used a leukotriene receptor antagonist, one used omalizumab or a boost of inhaled corticosteroids, and the largest study, (12,179 children), used a medication reminder letter. Whilst the risk of bias within individual studies was generally low, we downgraded the evidence quality due to imprecision associated with low participant numbers, poor consistency between studies, and indirect outcome ascertainment.A US study of 513 children with mild/severe asthma and allergic sensitisation was the only study to provide data for our primary outcome. In this study, the proportion of participants experiencing an exacerbation requiring oral corticosteroids or hospital admission in the 90 days after school return was significantly reduced to 11.3% in those receiving omalizumab compared to 21.0% in those receiving placebo (odds ratio 0.48, 95% confidence interval 0.25 to 0.92, moderate-quality evidence). The remaining studies used alternative exacerbation definitions. When data from two leukotriene receptor antagonist studies with comparable outcomes were combined in a random-effects model, there was no evidence of an effect upon exacerbations. There was no evidence that a seasonal medication reminder letter decreased unscheduled contacts for a respiratory diagnosis between September and December.Four studies recorded adverse events. There was no evidence that the proportion of participants experiencing at least one adverse event differed between intervention and usual care groups. Lack of data prevented planned subgroup and sensitivity analyses.

AUTHORS' CONCLUSIONS

Seasonal omalizumab treatment from four to six weeks before school return might reduce autumn asthma exacerbations. We found no evidence that this strategy is associated with increased adverse effects other than injection site pain, but it is costly. There were no data upon which to judge the effect of this or other seasonal interventions on asthma control, quality of life, or asthma-related death. In future studies definitions of exacerbations should be provided, and standardised where possible. To investigate possible differential effects according to subgroup, participants in future trials should be well characterised with respect to baseline asthma severity and exacerbation history in addition to age and gender.

Association of Mycoplasma pneumoniae infection with increased risk of asthma in children

The present study was conducted to investigate the relationship between Mycoplasma pneumoniae (MP) infection and the risk of asthma among children by detecting the rate of MP immunoglobulin M (MP-IgM) and the eosinophil (EOS) count. A total of 139 asthmatic children were enrolled as the case group and assigned into three groups: Group A (aged <3 years, n=42), group B (aged 3–8 years, n=45) and group C (aged >8 years, n=52). Additionally, 115 healthy children were enrolled in the control group. Enzyme-linked immunosorbent assay was used to measure the MP-IgM-positive rate. EOS count was detected in the experimental and control groups by using a hemocytometer analyzer. A meta-analysis was performed by using the Comprehensive Meta-Analysis version 2.0 software. The positive rates of the MP-IgM and EOS count in the experimental group were significantly higher than those in control group (both P<0.001). Furthermore, the asthmatic children in group C had a higher MP-IgM-positive rate and EOS count as compared to those in groups A and B, respectively (all P<0.05). Results from groups A and B were not statistically significant (all P>0.05). The meta-analysis further confirmed that asthmatic children had a higher MP-IgM-positive rate as compared to the healthy controls (P<0.001). Age-stratified analysis revealed that the MP-IgM-positive rate in asthmatic children aged ≥8 and <8 years was significantly higher than that in the healthy controls (P=0.003 and P<0.001). Asthmatic children had a higher MP-IgM-positive rate and EOS count as compared with controls, suggesting that the MP infection may be closely associated with the risk of asthma. Additionally, the positive rate of MP-IgM may indicate an important biological marker in predicting the development of asthma.

Virus and Mycoplasma pneumoniae prevalence in a selected pediatric population with acute asthma exacerbation

OBJECTIVE

To determine the prevalence of viral and atypical bacteria Mycoplasma pneumoniae infection in children experiencing asthma exacerbation and compare positive and negative subjects with regard to exacerbation severity, need for hospitalization, and treatment.

METHODS

One hundred sixty-nine asthmatic children aged 2-15 years old who were admitted to emergency rooms in Bogota, Colombia for acute asthma exacerbation were interviewed. Nasopharyngeal aspirates were taken for DNA and RNA extraction. M. pneumoniae and virus were detected by PCR using specific primers.

RESULTS

The prevalence of M. pneumoniae and viral infection in the study population was 12.4% and 83.7%, respectively. All subjects positive for M. pneumoniae were also positive for viral infection. Rhinovirus was the most frequently detected viral agent. No significant differences in severity of asthma exacerbations or in need for hospitalization between the virus or M. pneumoniae positive and negative groups were observed. A significantly lower percentage of M. pneumoniae positive subjects had used inhaled steroids over the six months prior to asthma exacerbation compared to M. pneumoniae negative subjects (38.1% vs. 68.2%), suggesting that inhaled corticosteroids may have a protective effect against M. pneumoniae infections.

CONCLUSIONS

The M. pneumoniae and virus prevalence found in this study were similar to those described in the literature. The 100% co-infection rate observed suggests that viral infection can predispose patients to M. pneumoniae infection, and that this interaction may trigger asthmatic exacerbation. Further studies should be done to confirm the protective effect of inhaled corticosteroids on M. pneumoniae infection in patients with asthma exacerbations.

Understanding the Association of Human Rhinovirus with Asthma

Human rhinoviruses are ubiquitous seasonal pathogens. They have known associations with first onset of wheezing illnesses in children and with asthma exacerbations in patients of all ages. It is not yet certain whether human rhinoviruses play a direct role in the pathogenesis of asthma by activating deleterious inflammatory responses or if they only serve as a catalyst to accelerate the disease in genetically predisposed individuals. There have been previously demonstrated reductions in the development of the asthmatic phenotype with passive immunization against respiratory syncytial virus; however, in the case of rhinovirus, there are barriers to effective vaccine development, such as the lack of a common antigenic target due to alterations of surface markers among subtypes. It remains to be determined whether certain subtypes of human rhinovirus are more asthmagenic and therefore worthy of greater attention as vaccine candidates, but several studies have suggested that RV-C and certain RV-A strains may be more strongly linked with asthma.

Hospitalizations and outpatient visits for rhinovirus-associated acute respiratory illness in adults

BACKGROUND

Rhinovirus is linked to asthma exacerbations and chronic obstructive pulmonary disease exacerbations in adults. The severity and rates of rhinovirus acute respiratory illnesses (ARIs) in adults are uncertain.

OBJECTIVES

We sought to determine rhinovirus-associated ARI rates in adults presenting for care in multiple settings and identify factors associated with rhinovirus detection.

METHODS

This prospective, population-based cohort enrolled Tennessee residents 18 years or older in the emergency department (ED), outpatient clinics, or hospitalized for ARI from December 2008 to May 2010. Nasal/throat swabs were collected and tested for rhinovirus and other viruses by using RT-PCR. Rates of ED visits and hospitalizations were calculated and rhinovirus-positive and rhinovirus-negative patients were compared.

RESULTS

Among 2351 enrollees, rhinovirus was detected in 247 (11%). There were 7 rhinovirus-associated ED visits and 3 hospitalizations per 1000 adults annually. Patients with rhinovirus, compared with virus-negative ARI, were more likely to present with wheezing (odds ratio [OR], 1.7; 95% CI, 1.23-2.35; P < .001), to be a current smoker (OR, 2.31; 95% CI, 1.68-3.19) or live with a smoker (OR, 1.72; 95% CI, 1.10-2.67), have a history of chronic respiratory disease (OR, 1.61; 95% CI, 1.17-2.22), and were less likely to be hospitalized versus seen in the outpatient setting (OR, 0.58; 95% CI, 0.41-0.83).

CONCLUSIONS

Rhinovirus is associated with a substantial number of ED visits and hospitalizations for ARIs in adults. There may be modifiable factors that can reduce the likelihood of presenting with rhinovirus-associated ARIs.

Wheezing exacerbations in early childhood: evaluation, treatment, and recent advances relevant to the genesis of asthma

Children who begin wheezing during early childhood are frequently seen by health care providers in primary care, in hospitals, and in emergency departments, and by allergists and pulmonologists. When a young child, such as the 2 year-old patient presented here, is evaluated for wheezing, a frequent challenge for clinicians is to determine whether the symptoms represent transient, viral-induced wheezing or whether sufficient risk factors are present to suspect that the child may experience recurrent wheezing and develop asthma. Most factors that influence prognosis are not mutually exclusive, are interrelated (ie, cofactors), and often represent gene-environment interactions. Many of these risk factors have been, and continue to be, investigated in prospective studies to decipher their relative importance with the goal of developing new therapies and interventions in the future. The etiologies of wheezing in young children, diagnostic methods, treatment, prognostic factors, and potential targets for prevention of the development of asthma are discussed.

Exacerbation of asthma and airway infection: is the virus the villain?

Objetivo

Rever a literatura disponível sobre a relação entre infecção viral aguda do trato respiratório e o desencadeamento de exacerbações da asma, identificando os vírus mais prevalentes, os métodos de detecção, bem como os aspectos preventivos e terapêuticos.

Fonte dos dados

Foi realizada uma busca nas bases de dados PubMed, SciELO e Lilacs utilizando os descritores: asma, exacerbação, vírus, criança e infecção respiratória aguda, entre os anos de 2002 e 2013.

Síntese dos dados

Foram selecionados 42 artigos originais que tratavam da identificação de vírus respiratórios durante episódios de exacerbação da asma, em sua maioria estudos transversais. Houve ampla variação na metodologia dos trabalhos avaliados, principalmente em relação à idade das crianças e métodos de coleta e detecção viral. Os resultados apontam que, em até 92,2% das exacerbações, um agente viral foi potencialmente o principal fator desencadeante, sendo o rinovírus humano o mais identificado. O padrão de circulação viral pode ter sido responsável pela sazonalidade das exacerbações. A associação entre infecção viral e inflamação alérgica parece ser determinante para levar ao descontrole clínico‐funcional da asma, porém poucos estudos avaliaram outros fatores desencadeantes em associação com a infecção viral.

Conclusões

Os vírus respiratórios estão presentes na maioria das crianças asmáticas durante os episódios de exacerbação. Os mecanismos fisiopatológicos envolvidos ainda não estão totalmente estabelecidos e o sinergismo entre a inflamação alérgica e infecção viral parece determinar o descontrole da doença. O papel dos outros agentes desencadeantes e protetores não estão claramente determinados.

Exacerbation of asthma and airway infection: is the virus the villain?

OBJECTIVE

To review the available literature on the association between acute viral respiratory tract infection and the onset of asthma exacerbations, identifying the most prevalent viruses, detection methods, as well as preventive and therapeutic aspects.

SOURCES

A search was conducted in PubMed, Lilacs, and SciELO databases, between the years 2002 and 2013, using the following descriptors: asthma exacerbation, virus, child, and acute respiratory infection.

SUMMARY OF THE FINDINGS

A total of 42 original articles addressing the identification of respiratory viruses during episodes of asthma exacerbation were selected, mostly cross-sectional studies. There was a wide variation in the methodology of the assessed studies, particularly in relation to the children's age and methods of collection and viral detection. The results indicate that, in up to 92.2% of exacerbations, a viral agent was potentially the main triggering factor, and human rhinovirus was the most frequently identified factor. The pattern of viral circulation may have been responsible for the seasonality of exacerbations. The association between viral infections and allergic inflammation appears to be crucial for the clinical and functional uncontrolled asthma, but few studies have evaluated other triggering factors in association with viral infection.

CONCLUSIONS

Respiratory viruses are present in the majority of asthmatic children during episodes of exacerbation. The involved physiopathological mechanisms are yet to be fully established, and the synergism between allergic inflammation and viral infection appears to determine uncontrolled disease. The role of other triggering and protective agents is yet to be clearly determined.

[Value of routine identification of respiratory infectious agents in children hospitalized with an acute asthma exacerbation]

Introduction

Chez l’enfant les exacerbations d’asthme sont le plus souvent déclenchées par une infection respiratoire. L’objectif de cette étude était d’évaluer l’intérêt de l’identification des pathogènes respiratoires chez les enfants hospitalisés pour une exacerbation d’asthme.

Patients et méthodes

Il s’agit d’une étude rétrospective incluant tout enfant hospitalisé pour une exacerbation d’asthme dans notre unité entre janvier 2010 et décembre 2011 et analysant la prescription des examens microbiologiques, leurs indications, leur rendement, leur impact sur la prise en charge médicale et leur coût.

Résultats

Cent quatre-vingt-dix-sept enfants ont été inclus. Une recherche d’agent pathogène respiratoire avait été réalisée chez 157 enfants (79,7 %), surtout en cas d’infection oto-rhino-laryngologique (ORL), d’hypoxémie ou de pneumonie. Un virus avait été identifié chez 30 (23,8 %) des 126 enfants prélevés. Les analyses bactériologiques avaient eu un rendement faible puisque seulement 3,2 % des analyses par amplification génique (PCR) pour Mycoplasma pneumoniae avaient été positives (n = 4/125). Aucune autre bactérie n’avait été identifiée. Aucun lien n’a pu être établi entre les résultats microbiologiques et la gravité de l’exacerbation. La prise en charge thérapeutique avait été peu modifiée par ces résultats. Le coût global avait été de plus de 40 400 euros pour les 2 ans d’étude.

Conclusion

D’après nos résultats la recherche de pathogènes respiratoires au cours des exacerbations d’asthme a un intérêt modéré en dehors de l’aspect épidémiologique. L’impact du rhinovirus, du coronavirus, du bocavirus et de l’entérovirus, non recherchés en routine hospitalière, reste cependant à préciser.

Comparison of Mycoplasma pneumoniae Infections in asthmatic children versus asthmatic adults

BACKGROUND

Mycoplasma pneumoniae has been implicated in asthma exacerbations and chronic asthma. A 2-year longitudinal study has been conducted to investigate the role of M. pneumoniae infections in 168 and 20 hospitalized children and adults, respectively, with asthma exacerbation compared with outpatients (88 children and 48 adults) with chronic asthma (without an exacerbation). The prevalence of Chlamydia pneumoniae and respiratory viruses was also assessed in these 2 populations.

METHODS

Lung function testing, blood sampling and microbiological testing (polymerase chain reaction, culture and serology) were performed for 256 children and 68 adults followed by a 7-week, follow-up visit with repeated blood sampling for serological testing and phone interviews at 6 and 12 months later.

RESULTS

M. pneumoniae infection was more prevalent in children with chronic asthma (13.6%) compared with children with exacerbation (7.1%), while the reverse was true in adults (6.3 vs. 10.0%, respectively). However, these differences were not statistically significant. Acute C. pneumoniae infection was identified in 3.9% of children and 7.4% adults. Children seen for chronic asthma were significantly more likely to be infected with C. pneumoniae than children hospitalized for an asthma exacerbation. Viruses were the most prevalent microorganisms detected in children with an asthma exacerbation. No differences in the outcome parameters were identified between M. pneumoniae-infected and noninfected patients.

CONCLUSIONS

The present study suggests that M. pneumoniae does not play a direct role in the pathogenicity of acute or chronic asthma in most children.

Asthma and Microbes: A New Paradigm

Asthma is worldwide at pandemic levels for the past 30 years but is increasing at a greater rate in more affluent societies. It is a heterogeneous disorder caused by interaction between genetic predisposition, atopy, and environmental factors, including allergens, air pollution, and respiratory infections. The pathological aspects and pathophysiological mechanisms are reviewed in this chapter. Allergens or infectious agents may stimulate Th-2 inflammation which causes activation of IL-13, eosinophils, and increase IgE levels, subsequently leading to bronchial smooth muscle hypercontraction. Respiratory viral infections are well-known causes of precipitation of acute asthma exacerbations in 50–60 % of attacks. There is also increasing evidence that bacterial infections, Chlamydia pneumoniae, and Mycoplasma pneumoniae, may contribute to the onset and course of asthma. The two main hypothesis of microbial genesis of asthma that has arisen in the past 20–30 years appears to be incongruous, but are not, are the hygiene hypothesis of asthma, and the virus-related asthma, early onset of viral bronchiolitis in the susceptible hosts being responsible for later development of asthma. The clinical and experimental evidences to support these contentions are reviewed and critiqued.

IL-17-producing peripheral blood CD177+ neutrophils increase in allergic asthmatic subjects

Background

A T helper cell (T_H) 17-biased response has been observed in patients with allergic asthma, particularly in those with neutrophil accumulation in the lung. Therefore, we sought to test the hypothesis that neutrophils might be an important source of interleukin (IL)-17 in allergic asthma.

Methods

Whole peripheral blood cells from non-asthmatic control subjects (n = 17) and patients with mild asthma (n = 7), moderate but persistent asthma (n = 4), or acute asthma (n = 6) were analyzed for IL-17A expression in CD177⁺ neutrophils. IL-17A expression was also analyzed in CD3⁺CD4⁺ and CD3⁺CD8⁺ lymphocyte populations. Asthmatic patients were classified as allergic to fungi, indoor allergens, or other allergens (e.g., pollen) based on a positive intradermal allergy test reaction.

Results

The percentage of CD177⁺ neutrophils in whole blood of asthmatic patients was higher than in healthy controls and highest in the moderate asthma group. Furthermore, the percentage of CD177⁺IL-17⁺ neutrophils was elevated in patients with mild asthma, whereas the CD4⁺ IL-17⁺ lymphocyte population was higher in asthmatic patients and highest in those with moderate but persistent asthma. We also found that the four patients that were allergic to fungi had the highest percentage of CD177⁺IL17⁺ neutrophils and CD8⁺IL17⁺ lymphocytes.

Conclusion

IL17⁺CD177⁺ Neutrophils increase in allergic asthma patients especially when allergic to fungi. This cell population, through release of IL-17, might be contributing during the initial phase asthmatic disease and/or during disease progression but its role has not yet been established.

Can a school-based hand hygiene program reduce asthma exacerbations among elementary school children?

BACKGROUND

Viral upper respiratory tract infections have been implicated as a major cause of asthma exacerbations among school-aged children. Regular hand washing is the most effective method to prevent the spread of viral respiratory tract infections, but effective hand-washing practices are difficult to establish in schools.

OBJECTIVES

This randomized controlled trial evaluated whether a standardized regimen of hand washing plus alcohol-based hand sanitizer could reduce asthma exacerbations more than schools' usual hand hygiene practices.

METHODS

This was a 2-year, community-based, randomized controlled crossover trial. Schools were randomized to usual care and then intervention (sequence 1) or intervention and then usual care (sequence 2). Intervention schools were provided with alcohol-based hand sanitizer, hand soap, and hand hygiene education. The primary outcome was the proportion of students experiencing an asthma exacerbation each month. Generalized estimating equations were used to model the difference in the marginal rate of exacerbations between sequences while controlling for individual demographic factors and the correlation within each student and between students within each school.

RESULTS

Five hundred twenty-seven students with asthma were enrolled among 31 schools. The hand hygiene intervention did not reduce the number of asthma exacerbations compared with the schools' usual hand hygiene practices (P = .132). There was a strong temporal trend because both sequences experienced fewer exacerbations during year 2 compared with year 1 (P < .001).

CONCLUSIONS

Although the intervention was not found to be effective, the results were confounded by the H1N1 influenza pandemic that resulted in substantially increased hand hygiene behaviors and resources in usual-care schools. Therefore these results should be viewed cautiously.

Chlamydia pneumoniae infection associated with uncontrolled asthma: a hospital based cross sectional study

OBJECTIVES

To evaluate the proportion of anti- Chlamydia pneumoniae (Cp) IgM positivity in patients with uncontrolled asthma and partly controlled childhood asthma and their clinical correlates.

METHODS

This was a hospital based cross sectional study. Children aged 1 to 12 y suffering from asthma were included after written informed parental consent. For diagnosis and classification of uncontrolled and partly controlled asthma, GINA guidelines 2009 were used. Anti-Cp IgM was tested by using an enzyme linked immunosorbent assay (ELISA) and value of antibody index ≥ 0.90 was considered positive. Data was collected on demographic, clinical and investigative variables including chest radiograph posterior-anterior view.

RESULTS

From August 2010 through August 2011 44 patients hospitalized with uncontrolled asthma in exacerbation and 45 patients with partly controlled asthma from ambulatory care settings were included. Anti-Cp IgM was positive in 25 % (n = 11/44) and 6.7 % (n = 3/45) patients with uncontrolled and partly controlled asthma, respectively (Odds ratio = 4.67, χ (2) = 5.64, 95 % CI 1.20-18.10, p 0.0 17). Among the patients of uncontrolled asthma, duration of hospital stay was longer in anti-Cp IgM positive patients (9 ± 2.19 vs. 7.19 ± 2.10 d, p 0.02).

CONCLUSIONS

Since anti-Cp IgM positivity was associated with age >5 y and radiological consolidation in uncontrolled asthma in exacerbation, specific treatment of Chlamydia pneumoniae must be actively considered.

Allergens and bacteria interaction in the induction of basophil activation: is this the lost ring between allergy and infections in pediatric patients?

PURPOSE OF REVIEW

The aim of this review is to describe the relationships between allergy and infectious diseases, with specific attention on bacterial infection. According to the most recent literature, bacteria could be considered also as one of the major causes of asthma exacerbations that we need to further explore.

RECENT FINDINGS

The availability of novel methods to detect large panels of pathogens, including viruses and bacteria specific for the upper respiratory tract, together with the capacity of evaluating how basophils are activated, has changed the point of view of the mechanisms related to asthma exacerbations. The recent finding that basophils are activated in the presence of suboptimal doses of allergens and bacteria has been recently described and may explain the clinical behavior of allergy exacerbation. Indeed the activation of basophils induces the secretion of mediators, which, at bronchial level, may cause bronchospasm that leads to an asthma exacerbation in patients with infection. The contrary is also true.

SUMMARY

Although the explanations for these facts are numerous, at present, bacteria seem to play a relevant role in the worsening of asthma in infected patients.

Asthma exacerbations: origin, effect, and prevention

Asthma is the most common chronic respiratory disease, affecting up to 10% of adults and 30% of children in the Western world. Despite advances in asthma management, acute exacerbations continue to occur and impose considerable morbidity on patients and constitute a major burden on health care resources. Respiratory tract viruses have emerged as the most frequent triggers for exacerbations in both children and adults; however, the mechanisms underlying these remain poorly understood. More recently, it has become increasingly clear that interactions might exist between viruses and other triggers, increasing the likelihood of an exacerbation. In this article we begin with an overview of the health, economic, and social burden that exacerbations of asthma carry with them. This is followed by a review of the pathogenesis of asthma exacerbations, highlighting the various triggers responsible and multiple interactions that exist between them. The final section first addresses what preventative measures are currently available for asthma exacerbations and subsequently examines which of the new treatments in development might lessen the burden of exacerbations in the future.

Clinical spectrum of human rhinovirus infections in hospitalized Hong Kong children

BACKGROUND

Human rhinovirus (HRV) is classified into A, B, and C genogroups. HRVs cause mild upper respiratory infections, but HRV-C was recently found to be a major cause of asthma exacerbation in whites. This study elucidated disease spectrum of HRV infections among Hong Kong children hospitalized with respiratory illnesses.

METHODS

This retrospective study recruited 128 children with asthma exacerbations and 192 inpatient controls without allergy and hospitalized for respiratory illnesses within the same week. Their clinical information was retrieved from case records. HRVs in nasopharyngeal aspirates were detected by molecular assays using primers targeting consensus VP4/VP2 coding regions, and their genogroups identified by sequencing.

RESULTS

The mean (standard deviation) age of cases and controls was 5.6 (3.6) years and 5.4 (3.8) years, respectively (P = 0.601). HRV was detected in 107 (84.9%) cases and 63 (33.0%) controls (P < 0.0001), and HRV-C in 69.8% and 18.8% of these groups, respectively (P < 0.0001). Detection of HRV-A and -B was similar between these groups (P > 0.15). More subjects with HRV-C needed oxygen supplementation (11.1% vs. 2.6%; P = 0.043). Among controls, HRV infection was associated with acute bronchiolitis (P < 0.001) and bronchitis (P = 0.04), which paralleled those of HRV-C. HRV-A was associated with acute bronchiolitis (P = 0.005). Phylogenetic analysis revealed a diverse group of HRV serotypes (21 for HRV-A, 2 for HRV-B, and 32 for HRV-C).

CONCLUSIONS

HRV-C is associated with asthma exacerbation, whereas the presence of all HRVs, or either HRV-A or HRV-C alone, is associated with wheezing respiratory infections in nonasthmatic children. HRV is an important respiratory virus responsible for childhood wheezing illnesses.

Redesigning a large school-based clinical trial in response to changes in community practice

BACKGROUND

Asthma exacerbations are seasonal with the greatest risk in elementary-age students occurring shortly after returning to school following summer break. Recent research suggests that this seasonality in children is primarily related to viral respiratory tract infections. Regular hand washing is the most effective method to prevent the spread of viral respiratory infections; unfortunately, achieving hand washing recommendations in schools is difficult. Therefore, we designed a study to evaluate the effect of hand sanitizer use in elementary schools on exacerbations among children with asthma.

PURPOSE

To describe the process of redesigning the trial in response to changes in the safety profile of the hand sanitizer as well as changes in hand hygiene practice in the schools.

METHODS

The original trial was a randomized, longitudinal, subject-blinded, placebo-controlled, community-based crossover trial. The primary aim was to evaluate the incremental effectiveness of hand sanitizer use in addition to usual hand hygiene practices to decrease asthma exacerbations in elementary-age children. Three events occurred that required major modifications to the original study protocol: (1) safety concerns arose regarding the hand sanitizer's active ingredient; (2) no substitute placebo hand sanitizer was available; and (3) community preferences changed regarding hand hygiene practices in the schools.

RESULTS

The revised protocol is a randomized, longitudinal, community-based crossover trial. The primary aim is to evaluate the incremental effectiveness of a two-step hand hygiene process (hand hygiene education plus institutionally provided alcohol-based hand sanitizer) versus usual care to decrease asthma exacerbations. Enrollment was completed in May 2009 with 527 students from 30 schools. The intervention began in August 2009 and will continue through May 2011. Study results should be available at the end of 2011.

LIMITATIONS

The changed design does not allow us to directly measure the effectiveness of hand sanitizer use as a supplement to traditional hand washing practices.

CONCLUSIONS

The need to balance a rigorous study design with one that is acceptable to the community requires investigators to be actively involved with community collaborators and able to adapt study protocols to fit changing community practices.

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

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

Abstract

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

Bacterial infections and pediatric asthma

Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis seem to have no role in asthma in children. Mycoplasma pneumoniae and Chlamydophila pneumoniae can induce wheezing and cause asthma exacerbations in children, and chronic Chlamydophila infections may even participate in asthma pathogenesis. However, studies have failed to show any benefits from antibiotics for incipient or stable pediatric asthma, as well as for asthma exacerbations in children. Exposure to antibiotics in infancy has been an independent risk factor of later asthma in many studies. A recent study applying molecular biology methods to lower airway samples provided preliminary evidence that lower airways are not sterile but have their own protective microbiota, which can be disturbed in lung diseases like asthma.

Host and viral factors associated with severity of human rhinovirus-associated infant respiratory tract illness

BACKGROUND

Risk factors for severe human rhinovirus (HRV)-associated infant illness are unknown.

OBJECTIVES

We sought to examine the role of HRV infection in infant respiratory tract illness and assess viral and host risk factors for HRV-associated disease severity.

METHODS

We used a prospective cohort of term, previously healthy infants enrolled during an inpatient or outpatient visit for acute upper or lower respiratory tract illness during the fall-spring months of 2004-2008. Illness severity was determined by using an ordinal bronchiolitis severity score, with higher scores indicating more severe disease. HRV was identified by means of real-time RT-PCR. The VP4/VP2 region from HRV-positive specimens was sequenced to determine species.

RESULTS

Of 630 infants with bronchiolitis or upper respiratory tract illnesses (URIs), 162 (26%) had HRV infection; HRV infection was associated with 18% of cases of bronchiolitis and 47% of cases of URI. Among infants with HRV infection, 104 (64%) had HRV infection alone. Host factors associated with more severe HRV-associated illness included a maternal and family history of atopy (median score of 3.5 [interquartile range [IQR], 1.0-7.8] vs 2.0 [IQR, 1.0-5.2] and 3.5 [IQR, 1.0-7.5] vs 2.0 [IQR, 0-4.0]). In adjusted analyses maternal history of atopy conferred an increase in the risk for more severe HRV-associated bronchiolitis (odds ratio, 2.39; 95% CI, 1.14-4.99; P = .02). In a similar model maternal asthma was also associated with greater HRV-associated bronchiolitis severity (odds ratio, 2.49, 95% CI, 1.10-5.67; P = .03). Among patients with HRV infection, 35% had HRVA, 6% had HRVB, and 30% had HRVC.

CONCLUSION

HRV infection was a frequent cause of bronchiolitis and URIs among previously healthy term infants requiring hospitalization or unscheduled outpatient visits. Substantial viral genetic diversity was seen among the patients with HRV infection, and predominant groups varied by season and year. Host factors, including maternal atopy, were associated with more severe infant HRV-associated illness.

The infectious march: the complex interaction between microbes and the immune system in asthma

There has been significant progress in our knowledge about the relationship between infectious disease and the immune system in relation to asthma, but many unanswered questions still remain. Respiratory tract infections such as those caused by respiratory syncytial virus and rhinovirus during the first 2 years of life are still clearly associated with later wheezing and asthma, but the mechanism has not been completely worked out. Is there an "infectious march" triggered by infection in infancy that progresses to disease pathology or are infants who contract respiratory infections predisposed to developing asthma? This review focuses on the common themes in the interaction between microbes and the immune system, and presents a critical appraisal of the evidence to date. The various mechanisms whereby microbes alter the immune response and how this might influence asthma are discussed along with new and promising clinical practices for prevention and therapy. Recent advances in using sensitive polymerase chain reaction detection methods have allowed more rigorous testing of the causality hypothesis of virus infection leading to asthma, but the evidence is still equivocal. Various exceptions and inconsistencies in the clinical trials are discussed in light of new guidelines for subject inclusion/exclusion in hopes of providing some standardization. Despite past failures in vaccination and disappointing results of some clinical trials, the new strategies for prophylaxis including RNA interference and targeted delivery of microbicides offer a large dose of hope to a world suffering from an increasing incidence of asthma as well as a huge burden of health care cost and loss of quality of life.

New human rhinovirus species and their significance in asthma exacerbation and airway remodeling

Asthma is the most common chronic disease of childhood, affecting 10% to 15% of all children. Several different stimuli including allergens, tobacco smoke, certain drugs, and viral or bacterial infections are known to exacerbate asthma symptoms. Among these triggers, viruses are frequent inducers of asthma exacerbations, with human rhinoviruses being the most common in children and adults. This article describes the different species of this virus and their roles as major triggers of asthma exacerbations.

Viruses and atypical bacteria associated with asthma exacerbations in hospitalized children

OBJECTIVES AND WORKING HYPOTHESIS: To evaluate the prevalence of respiratory viruses Mycoplasma pneumoniae and Chlamydophila pneumoniae and gain insight into their seasonal circulation pattern in children with acute asthma exacerbations in a temperate southern hemisphere region.

STUDY DESIGN

Patients hospitalized between 3 months and 16 years of age were included in a 1-year prospective, observational, cross-sectional study. Respiratory secretions were collected and the presence of different viruses and atypical bacteria analyzed by immunofluorescence and polymerase chain reaction.

RESULTS

Two hundred nine patients (118 females) aged (mean +/- SD) 4.4 +/- 4 years were included. A potential causative agent was detected in 78% of the patients. The most frequently detected viruses were respiratory syncytial virus (HRSV) (n = 85; 40%) and rhinovirus (HRV) (n = 52; 24.5%); M. pneumoniae and C. pneumoniae were detected in 4.5% and 2% of the cases, respectively. Patients with HRSV (vs. HRV) were hospitalized for a longer time (6.7 vs. 5.2 days, P = 0.012), required more days of oxygen supply (5.1 vs. 3.4, P = 0.005), had a longer duration of the exacerbation before hospitalization (3.6 vs. 1.9 days, P = 0.001) and were younger (3.7 vs. 5.1 years, P = 0.012). Three peaks of admissions were observed. A first peak (early autumn) caused by HRV, a second peak (winter) caused mainly by HRSV and a third one (spring), caused by HRSV, an increase in HMPV together with a second outbreak of HRV.

CONCLUSIONS

Children with an acute asthma exacerbation presented a high prevalence of respiratory viruses. Most hospitalizations corresponded to seasonal increases in prevalence of HRV and HRSV.

Double-stranded RNA exacerbates pulmonary allergic reaction through TLR3: implication of airway epithelium and dendritic cells

Respiratory viral infections have been implicated in exacerbations of allergic asthma, characterized by a Th2-biased immune response. Respiratory viruses target airway epithelial cells and dendritic cells (DCs). Their activation is, at least in part, mediated by the TLR3-dependent recognition of virus-derived dsRNA. To elucidate the role of epithelial cells and DCs and the implication of TLR3/Toll/IL-1R domain-containing adaptor-inducing IFN-beta (TRIF) pathway, we developed a mouse model of lung allergic exacerbation. The effect of intranasal administration of dsRNA in OVA-sensitized wild-type mice and TRIF(-/-) mice was evaluated on airway hyperresponsiveness and pulmonary inflammation. Our data demonstrated that treatment with dsRNA significantly increased the airway hyperresponsiveness, the lung inflammation, and the OVA-specific Th2 response. This was associated with an infiltrate of eosinophils, myeloid DCs, and T lymphocytes. TRIF activation was required for the development of dsRNA-induced exacerbation of the allergic reaction. Intratracheal transfer of IL-4/dsRNA/OVA-pretreated DCs also triggered exacerbation of the allergic reaction, whereas cells primed with dsRNA/OVA had a more limited effect. dsRNA-induced production of CCL20 by airway epithelium was associated with DC recruitment. In vivo and in vitro treatment with dsRNA amplified airway epithelial production of the pro-Th2 chemokines CCL11 and CCL17, their secretion being enhanced by Th2 cytokines. In conclusion, dsRNA derived from respiratory viruses trigger exacerbation of the pulmonary allergic reaction through TLR3/TRIF-dependent pathway. Moreover, Th2 cytokines participate in this process by modulating the response of airway epithelium and DCs to dsRNA.

Controller medications and their effects on asthma exacerbations temporally associated with upper respiratory infections

BACKGROUND

Exacerbations are a major risk and a cause of asthma morbidity and healthcare utilization. Viral-induced upper respiratory tract infections are the most frequent trigger of asthma-related exacerbations. Studies have traditionally assessed exacerbations without documentation regarding exacerbation etiology. Therefore, it remains unknown whether asthma medications can alter exacerbation susceptibility based on a specific etiology.

OBJECTIVE

To examine whether treatment with inhaled corticosteroids plus long-acting beta(2)-agonists reduced the number of exacerbations associated with upper respiratory tract infections versus inhaled corticosteroids alone.

METHODS

Two large datasets comparing treatment with fluticasone propionate and fluticasone propionate plus salmeterol were analyzed, including the number of clinically reported upper respiratory tract infections, asthma-related exacerbations, and the presence of an exacerbation and concurrent report of an upper respiratory tract infection.

RESULTS

Both treatment groups had similar incidences of upper respiratory tract infections. Of those reporting an upper respiratory tract infection, statistically significantly fewer reported an asthma-related exacerbation comparing fluticasone propionate plus salmeterol with fluticasone propionate (p=0.0057).

DISCUSSION

This retrospective analysis suggests that therapy with fluticasone propionate plus salmeterol provides protection against asthma exacerbations temporally associated with upper respiratory tract infections. This retrospective analysis supports the hypothesis that specific therapeutic approaches to mitigate virus-associated exacerbations may benefit asthma care. Well-controlled prospective studies are warranted.

Management of bacterial infections in children with asthma

Respiratory viruses are the single most common causes of asthma exacerbations in children. Rhinovirus-induced wheezing is a risk factor for chronic asthma, but its mechanism has remained unknown. Human bocavirus is a common finding in wheezing children, but its role as a respiratory pathogen is still unclear. Mycoplasma pneumoniae may, like viruses, induce wheezing and asthma exacerbation. Chlamydia pneumoniae and, in recent studies, Chlamydia trachomatis, may not only induce asthma exacerbations but may also be involved in the pathogenesis of chronic asthma. Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis are often involved in respiratory infections associated with wheezing, but there is no evidence for their active role in asthma pathogenesis or exacerbation. This review summarizes current knowledge on the association between respiratory infections and asthma in children, with a special focus on the role of antibiotics in incipient asthma, asthma exacerbation and chronic stable asthma.

Virus vaccines and children with asthma

PURPOSE OF REVIEW

To describe what is currently known about the role of virus vaccines in the pathogenesis of asthma and atopy and summarize their role in the prevention of morbidity due to childhood asthma.

RECENT FINDINGS

The development of virus vaccines and their incorporation into infant and childhood immunization programmes over the last few decades of the twentieth century have been accompanied by a striking concomitant rise in the incidence of asthma and atopy. However, a causal relationship is not supported by the majority of observational studies. The role of childhood immunization against respiratory viruses in the reduction of morbidity from asthma is another important public health issue. Recent findings suggest that influenza is not strongly associated with exacerbations of asthma in children, despite recommendations that this group should be immunized against it.

SUMMARY

Current evidence suggests that virus vaccination is well tolerated and does not lead to an increased incidence of asthma or atopy in children receiving vaccines. Debate continues regarding the place of respiratory virus vaccination in the therapeutic armamentarium for children with asthma. In the case of influenza, there appears to be an absence of harm, but benefit seems to be limited to younger children.

Multiplex molecular detection of respiratory pathogens in children with asthma exacerbation

BACKGROUND

Up to 80% of asthma exacerbations in white children are associated with viral upper respiratory infections. The relative importance of different respiratory pathogens and relevant microbiological data in Asian children are unclear. This study elucidated the epidemiology of respiratory infections in Hong Kong children with asthma exacerbation.

METHODS

A total of 209 children aged 3-18 years with asthma exacerbations and 77 controls with stable asthma were recruited. The severity of asthma exacerbations was assessed according to Global Initiative for Asthma guideline, and subjects aged 6 years or older performed exhaled nitric oxide and spirometric measurements. Nested multiplex polymerase chain reaction was used to detect 20 different respiratory pathogens.

RESULTS

Respiratory pathogens were detected in 105 (51.0%) subjects. The presence of any respiratory pathogen was associated with asthma exacerbation (odds ratio [OR], 2.77; 95% CI, 1.51-5.11; P < .001). Specifically, human rhinovirus (HRV) infection was more common among children with asthma exacerbation (OR, 2.38; 95% CI, 1.09-5.32; P = .018). All other pathogens or coinfections were not associated with asthmatic attacks. None of these respiratory infections was associated with the severity of asthma exacerbation (P > .15 for all). During peak HRV season in the winter of 2007 to 2008, this virus was detected in 46.4% of children with asthma exacerbations.

CONCLUSIONS

Respiratory viral infections are commonly found in children with asthma exacerbation, with HRV being the most important pathogen in our patients. Respiratory viral infection is a triggering factor for asthma exacerbation but does not correlate with its severity.

Distribution and seasonality of rhinovirus and other respiratory viruses in a cross-section of asthmatic children in Trinidad, West Indies

Background

Childhood asthma in the Caribbean is advancing in prevalence and morbidity. Though viral respiratory tract infections are reported triggers for exacerbations, information on these infections with asthma is sparse in Caribbean territories. We examined the distribution of respiratory viruses and their association with seasons in acute and stable asthmatic children in Trinidad.

Methods

In a cross-sectional study of 70 wheezing children attending the emergency department for nebulisation and 80 stable control subjects (2 to 16 yr of age) in the asthma clinic, nasal specimens were collected during the dry (n = 38, January to May) and rainy (n = 112, June to December) seasons. A multitarget, sensitive, specific high-throughput Respiratory MultiCode assay tested for respiratory-virus sequences for eight distinct groups: human rhinovirus, respiratory syncytial virus, parainfluenza virus, influenza virus, metapneumovirus, adenovirus, coronavirus, and enterovirus.

Results

Wheezing children had a higher [χ² = 5.561, p = 0.018] prevalence of respiratory viruses compared with stabilized asthmatics (34.3% (24) versus (vs.) 17.5% (14)). Acute asthmatics were thrice as likely to be infected with a respiratory virus (OR = 2.5, 95% CI = 1.2 – 5.3). The predominant pathogens detected in acute versus stable asthmatics were the rhinovirus (RV) (n = 18, 25.7% vs. n = 7, 8.8%; p = 0.005), respiratory syncytial virus B (RSV B) (n = 2, 2.9% vs. n = 4, 5.0%), and enterovirus (n = 1, 1.4% vs. n = 2, 2.5%). Strong odds for rhinoviral infection were observed among nebulised children compared with stable asthmatics (p = 0.005, OR = 3.6, 95% CI = 1.4 – 9.3,). RV was prevalent throughout the year (Dry, n = 6, 15.8%; Rainy, n = 19, 17.0%) and without seasonal association [χ² = 0.028, p = 0.867]. However it was the most frequently detected virus [Dry = 6/10, (60.0%); Rainy = 19/28, (67.9%)] in both seasons.

Conclusion

Emergent wheezing illnesses during childhood can be linked to infection with rhinovirus in Trinidad's tropical environment. Viral-induced exacerbations of asthma are independent of seasons in this tropical climate. Further clinical and virology investigations are recommended on the role of infections with the rhinovirus in Caribbean childhood wheeze.

High prevalence of human rhinovirus C infection in Thai children with acute lower respiratory tract disease

Objective

To determine the prevalence of human rhinoviruses (HRV) infections in children with lower respiratory disease in Thailand and monitor the association between species of HRV and clinical presentation in hospitalized paediatric patients.

Method

Two hundred and eighty-nine nasopharyngeal (NP) suction specimens were collected from hospitalized paediatric patients admitted to King Chulalongkorn Memorial Hospital, Thailand during February 2006–2007. Nucleic acids were extracted from each sample with subsequent amplification of VP4/2 by semi-nested RT-PCR for HRV detection. Other viral respiratory pathogens were also detected by PCR, RT-PCR or real time PCR. Nucleotide sequences of the VP4 region were used for genotyping and phylogenetic tree construction.

Result

In total, 87 of 289 specimens were positive for HRV indicating an annual prevalence of 30%. Wheezing or asthma exacerbation was the most common clinical presentation observed in infected patients. Sequence analysis and phylogenetic tree showed that 29 (33%) and 8 (9%) specimens belonged to HRV-A and HRV-B, respectively. Most of the HRV positive samples were HRV-C (58%). Moreover, species C was predominantly found in the paediatric population of Thailand in raining season (p < 0.05). The frequency of co-infection of HRV-C with other respiratory viral pathogens was approximately 40%.

Conclusion

HRV-C represents the predominant species and is one of the etiologic agents in acute lower respiratory tract infection, causes of wheezing and asthma exacerbation in infants and young children in Thailand.