Genetic variants in 17q12-21 locus and childhood asthma in Brazil: Interaction with Varicella zoster virus seropositivity.

BACKGROUND: Asthma is a complex disease with worldwide public health relevance, is related to environmental causes and a genetic predisposition. The chromosomal 17q12-21 locus has been consistently demonstrated to be associated with asthma risk. The effects of variants in the 17q12-21 locus on childhood asthma were first identified in a genome wide- association study. Since that time, those findings have been replicated in different populations but not in South American populations. OBJECTIVE: This study aimed to investigate the role of variants in the 17q12-21 locus on asthma in a sample of Brazilian children. METHODS: This was a cross-sectional study conducted on a cohort of 1247 children. These analyses used 50 Single Nucleotide Variants (SNVs) in the 17q12-21 locus were genotyped as part of a genome wide association study (GWAS). RESULTS: Four SNVs (rs4065275, rs12603332, rs73985228 and rs77777702) were associated with childhood asthma. The rs73985228 exhibited the strongest association across the different genetic models (OR, 95%CI 2.8, 1.44-3.21, p < 0.01). In an analysis that was stratified by atopy, two SNVs (rs73985228 and rs2715555) were found to be associated with atopic and non-atopic asthma. For the first time, we observed a significant interaction with seropositivity for the Varicella zoster virus (for rs4065275, p = 0.02, and for rs12603332, p = 0.04); i.e., the association was found in those who were seropositive but not in those who were seronegative for this virus. CONCLUSIONS: We confirmed the associations of variants in the 17q12-21 locus with atopic and non-atopic asthma and identified an interaction with seropositivity for the Varicella zoster virus.

Eosinophils and Respiratory Viruses.

Eosinophils have been mainly associated with parasitic infection and pathologies such as asthma. Some patients with asthma present a high number of eosinophils in their airways. Since respiratory viruses are associated with asthma exacerbations, several studies have evaluated the role of eosinophils against respiratory viruses. Eosinophils contain and produce molecules with antiviral activity, including RNases and reactive nitrogen species. They can also participate in adaptive immunity, serving as antigen-presenting cells. Eosinophil antiviral response has been demonstrated against some respiratory viruses in vitro and in vivo, including respiratory syncytial virus and influenza. Given the implication of respiratory viruses in asthma, the eosinophil antiviral role might be an important factor to consider in this pathology.

Asthma exacerbations in a subtropical area and the role of respiratory viruses: a cross-sectional study.

BACKGROUND: Multiple factors are involved in asthma exacerbations, including environmental exposure and viral infections. We aimed to assess the association between severe asthma exacerbations, acute respiratory viral infections and other potential risk factors. METHODS: Asthmatic children aged 4-14 years were enrolled for a period of 12 months and divided into two groups: those with exacerbated asthma (group 1) and non-exacerbated asthma (group 2). Clinical data were obtained and nasopharyngeal samples were collected through nasopharyngeal aspirate or swab and analysed via indirect fluorescent immunoassays to detect influenza A and B viruses, parainfluenza 1-3, adenovirus and respiratory syncytial virus. Rhinovirus was detected via molecular assays. Potential risk factors for asthma exacerbation were identified in univariate and multivariate analyses. RESULTS: In 153 children (group 1: 92; group 2: 61), median age 7 and 8 years, respectively, the rate of virus detection was 87.7%. There was no difference between groups regarding the frequency of virus detection (p = 0.68); however, group 1 showed a lower frequency (19.2%) of inhaled corticosteroid use (91.4%, p < 0.01) and evidence of inadequate disease control. In the multivariate analysis, the occurrence of three or more visits to the emergency room in the past 12 months (IRR = 1.40; p = 0.04) and nonadherence to inhaled corticosteroid (IRR = 4.87; p < 0.01) were the only factors associated with exacerbation. CONCLUSION: Our results suggest an association between asthma exacerbations, poor disease control and nonadherence to asthma medication, suggesting that viruses may not be the only culprits for asthma exacerbations in this population.

Virus más frecuentemente aislados en la exacerbación de asma y su correlación con nivelesde eosinófilos e inmunoglobulina E sérica total / Most commonly isolated viruses in asthma exacerbation and their correlation with eosinophil and total serum immunoglobulin E levels

Antecedentes. Las exacerbaciones de asma continúan siendo una causa de hospitalización en el Servicio de Urgencias. Los desencadenantesson alérgenos e infecciones, principalmente, de tipo viral. El objetivo fue determinar la relación entre los virus detectados durante la exacerbación asmática y los niveles de eosinófilos e inmunoglobulina E (IgE) sérica en pacientes pediátricos. Población y métodos. Estudio transversal analítico. Se incluyeron niños de cinco a quince años atendidos en Urgencias de Pediatría con exacerbación de asma, en el período de marzo de 2013 a febrero de 2016. Se obtuvo ácido ribonucleico viral en el aspirado nasofaríngeo con el kit CLART PneumoVir. Se cuantificaron los eosinófilos en la sangre periférica y los niveles de IgE sérica total. Se consideró eosinofilia un conteo ≥ 0,4 x 103/mm3 e IgE elevada, ≥ 350 UI/L. Se realizó la correlación de Pearson. Se definió significancia con valor de p ≤ 0,05.Resultados. De 211 niños con exacerbación de asma, en el 20%, se aisló un virus. Los virus aislados más frecuentemente fueron el rinovirus, el enterovirus y el virus sincitial respiratorio. Se encontró una correlación entre los niveles de eosinófilos e IgE sérica total en los niños con exacerbación de asma y rinovirus de 0,89, con una p= 0,0001.Conclusiones. Las infecciones por rinovirus, enterovirus y virus sincitial respiratorio son más frecuentes en las exacerbaciones de asma en menores de 15 años. Se observó una correlación entre los niveles de eosinófilos e IgE en presencia de rinovirus.

Background. Asthma exacerbations are still a cause of hospitalization at the Emergency Department. The triggers of asthma exacerbations include allergens and infections ­mostly viral­. The objective of this study was to establish the relationship between viruses detected during an asthma exacerbation and eosinophil and serum immunoglobulin E (IgE) levels in pediatric patients. Population and methods. Cross-sectional. analytical study. Children aged 5-15 years seen at the Pediatric Emergency Department with an asthma exacerbation in the period between March 2013 and February 2016 were included. Viral ribonucleic acid was extracted from nasopharyngeal aspirates using the CLART Pneumo Vir kit. Eosinophil levels were measured in peripheral blood and total IgE levels, in serum. Eosinophilia was defined as a count ≥ 0.4 x 103/mm3 and high IgE. as a level ≥ 350 IU/L. The Pearson's correlation was carried out. A value of p ≤ 0.05 was considered significant.Results. Out of 211 children with asthma exacerbation, a virus was isolated in 20%. The most commonly isolated viruses were rhinovirus. enterovirus, and respiratory syncytial virus. A correlation of 0.89 was established between eosinophil and total serum IgE levels in children with asthma exacerbation and rhinovirus, with a p value of 0.0001. Conclusions. Rhinovirus, enterovirus, and respiratory syncytial virus were the most common viruses in asthma exacerbations in children younger than 15 years. A correlation was established between eosinophil and IgE levels in the presence of rhinovirus.

Most commonly isolated viruses in asthma exacerbation and their correlation with eosinophil and total serum immunoglobulin E levels. / Virus más frecuentemente aislados en la exacerbación de asma y su correlación con niveles de eosinófilos e inmunoglobulina E sérica total.

BACKGROUND: Asthma exacerbations are still a cause of hospitalization at the Emergency Department. The triggers of asthma exacerbations include allergens and infections -mostly viral-. The objective of this study was to establish the relationship between viruses detected during an asthma exacerbation and eosinophil and serum immunoglobulin E (IgE) levels in pediatric patients. POPULATION AND METHODS: Cross-sectional. analytical study. Children aged 5-15 years seen at the Pediatric Emergency Department with an asthma exacerbation in the period between March 2013 and February 2016 were included. Viral ribonucleic acid was extracted from nasopharyngeal aspirates using the CLART Pneumo Vir kit. Eosinophil levels were measured in peripheral blood and total IgE levels, in serum. Eosinophilia was defined as a count ≥ 0.4 x 103/ mm3 and high IgE. as a level ≥ 350 IU/L. The Pearson's correlation was carried out. A value of p ≤ 0.05 was considered significant. RESULTS: Out of 211 children with asthma exacerbation, a virus was isolated in 20%. The most commonly isolated viruses were rhinovirus. enterovirus, and respiratory syncytial virus. A correlation of 0.89 was established between eosinophil and total serum IgE levels in children with asthma exacerbation and rhinovirus, with a p value of 0.0001. CONCLUSIONS: Rhinovirus, enterovirus, and respiratory syncytial virus were the most common viruses in asthma exacerbations in children younger than 15 years. A correlation was established between eosinophil and IgE levels in the presence of rhinovirus.

Antecedentes. Las exacerbaciones de asma continúan siendo una causa de hospitalización en el Servicio de Urgencias. Los desencadenantes son alérgenos e infecciones, principalmente, de tipo viral. El objetivo fue determinar la relación entre los virus detectados durante la exacerbación asmática y los niveles de eosinófilos e inmunoglobulina E (IgE) sérica en pacientes pediátricos. Población y métodos. Estudio transversal analítico. Se incluyeron niños de cinco a quince años atendidos en Urgencias de Pediatría con exacerbación de asma, en el período de marzo de 2013 a febrero de 2016. Se obtuvo ácido ribonucleico viral en el aspirado nasofaríngeo con el kit CLART PneumoVir. Se cuantificaron los eosinófilos en la sangre periférica y los niveles de IgE sérica total. Se consideró eosinofilia un conteo ≥ 0,4 x 103/mm3 e IgE elevada, ≥ 350 UI/L. Se realizó la correlación de Pearson. Se definió significancia con valor de p ≤ 0,05. Resultados. De 211 niños con exacerbación de asma, en el 20%, se aisló un virus. Los virus aislados más frecuentemente fueron el rinovirus, el enterovirus y el virus sincitial respiratorio. Se encontró una correlación entre los niveles de eosinófilos e IgE sérica total en los niños con exacerbación de asma y rinovirus de 0,89, con una p= 0,0001. Conclusiones. Las infecciones por rinovirus, enterovirus y virus sincitial respiratorio son más frecuentes en las exacerbaciones de asma en menores de 15 años. Se observó una correlación entre los niveles de eosinófilos e IgE en presencia de rinovirus.

Exacerbation of asthma and airway infection: is the virus the villain? / Exacerbação da asma e infecção das vias aéreas: o vírus é o vilão?

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 Articless 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. .

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 ...

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.

Neural-endocrine mechanisms of respiratory syncytial virus-associated asthma in a rat model.

We examined the underlying neural-endocrine mechanisms of asthma associated with respiratory syncytial virus infection. Thirty Sprague-Dawley rats were randomly divided into control group, respiratory syncytial virus (RSV) group, and anti-nerve growth factor (NGF) IgG group. An RSV infection model was established by nasal drip once a week. In the anti-NGF antibody intervention group, each rat was given an intraperitoneal injection of anti-NGF IgG 3 h before RSV infection. Optical microscopy and transmission electron microscopy were used to observe the structural changes in adrenal medulla cells. Changes in adrenaline and norepinephrine in serum were detected by ELISA. NGF expression was assayed by immunohistochemistry. Expression differences in synaptophysin mRNA were detected by RT-PCR. Transmission electron microscopy displayed widened adrenal medulla intercellular spaces, reduced chromaffin particle concentration, and increased mitochondria in the RSV infection group. At the same time, NGF expression was increased in the RSV infection group significantly. In addition, the adrenaline concentration was significantly decreased compared with the control and anti-NGF antibody groups. Synaptophysin mRNA expression was significantly increased in the RSV infection and anti-NGF antibody groups. However, compared with the RSV infection group, synaptophysin mRNA expression was significantly decreased in the anti-NGF antibody group. We conclude that RSV infection could induce adrenal medulla cell differentiation to nerve cells by over-expression of NGF, resulting in the decreased endocrine function found in asthma progression.

Viruses and atypical bacteria associated with asthma exacerbations in hospitalized children.

UNLABELLED: 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.

Identification of influenza, parainfluenza, adenovirus and respiratory syncytial virus during rhinopharyngitis in a group of Mexican children with asthma and wheezing.

BACKGROUND: Viral infections can promote allergic sensitization in genetically susceptible individuals. Besides, they are the main cause of wheezing in children. OBJECTIVE: To assess the frequency with which influenza, parainfluenza, adenovirus and respiratory syncytial virus (RSV) cause rhinopharyngitis in patients with asthma and wheezing. PATIENTS AND METHODS: Longitudinal, prospective study in which 168 patients with asthma and wheezing, who attended the outpatient allergy clinic of the National Institute of Pediatrics, Mexico, during the spring (from April through June), with clinical signs and symptoms of rhinopharyngitis were included. Samples of nasal secretions were taken with a long swab, and identification of RSV, adenovirus, infuenza A and B and parainfluenzae 1, 2 and 3 by means of direct immunofluorescence (DI) was carried out. RESULTS: Samples of nasal secretions were taken in 100 children with asthma and 68 with wheezing, aged 2-17 years. Viral identification was positive in 75% and 44.1% of the patients, respectively. By age group, RSV predominated among children in preschool age; and influenza A among children in school age and adolescents. Influenza A, adenovirus and parinfluenza 3 were identified more frequently in asthmatic children, whereas influenza A and RSV in patients with wheezing. Coinfection of two viruses was found in 17.1% of all patients with positive DI; the most frequent association was parainfluenza 1 and 2. CONCLUSIONS: Viral identification by means of DI is a fast and non-invasive technique that could favor the early beginning of antiviral treatments in children with asthma and wheezing.

Human bocavirus: a cause of severe asthma exacerbation in children.

Real-time polymerase chain reaction for human bocavirus (HBoV) was performed in nasopharyngeal aspirate specimens from 166 children over 2 years of age hospitalized for severe asthma exacerbation. Whereas HBoV was detected in 21 of these children (13%), it was found in only 1 of 50 ambulatory children with stable asthma (2%), suggesting a major role of HBoV in acute exacerbations in asthmatic children.

Efeito da pré-exposição de vias aéreas de ratos com enterotoxina estafilocócica do tipo B (SEB) sobre a inflamação alérgica pulmonar / Effect of the pre-exposition of rats airways with staphylococci enteroxin type B (SEB) on pulmonary allergic inflammation

As enterotoxinas estafilocócicas (SEs) são produzidas e excretadas por algumas cepas da bactéria Staphylococcus aureus. A asma é uma doença caracterizada por resposta inflamatória crônica das vias aéreas. A admnistrração sistêmica de SEB em coelhos...

The staphylococci enterotoxin (SEs) are produced and secreted by some kind of Staphylococcus aureus. The asthma is a disease characterized by a chronic inflammatory response of the airways. the systemic administration of SEB in rabbits causes a pulmonary inflammation characterized...

Adenovirus: neumonía, enfermedad pulmonar crónica y asma / Adenovirus: pneumonia, chronic lung disease and asthma

Las infecciones por ADV ocurren primariamente en niños menores de cinco años y dan cuenta del 2 a 5 por ciento de las infecciones respiratorias pediátricas y 4 a 10 por ciento de las neumonías. La severidad de las infecciones respiratorias bajas por ADV varía de acuerdo al serotipo involucrado y a factores del huésped como edad, respuesta inmune, factores socioeconómicos y ambientales. La fase aguda de la neumonía por ADV es con condensaciones pulmonares extensas, semejante a una neumonía bacteriana, acompañada de compromiso sistémico y de múltiples órganos muy severa, asociándose a morbilidad y mortalidad importantes. La fase crónica se caracteriza por sibilancias, crepitaciones y dificultad respiratoria, y a veces con dependencia de ventilación mecánica o de oxigeno de curso prolongado. Histológicamente esto corresponde a una Bronquiolitis Obliterante. Entre el 14 y el 50 por ciento de los pacientes pueden desarrollarla. Radiológicamente hay hiperinsuflación, hernias mediastínicas, atelectasias cambiantes y en TC mosaico y bronquiectasias. La evolución de los primeros años es tormentosa. Hacia la edad escolar se estabilizan con compromisos variables de la función pulmonar y persistencia del compromiso obstructivo hasta la adolescencia, edad en la que pueden aparecer nuevas complicaciones y evolucionan como las EPOC de los adultos. Otro grupo de pacientes desarrolla síntomas de asma. Los ADV gatillas crisis de asma y su ADN se ha encontrado en lavados broncoalveolares de asma persistente, todo lo cual lo ubica como un patógeno relevante.

[Human Metapneumovirus (hMPV) associated to severe bronchial asthmatic crisis]. / Metapneumovirus humano (hMPV) asociado con exacerbación de asma aguda bronquial severa.

Human Metapneumovirus (hMPV) is a recently reported agent of acute infection in the respiratory tract. It has been found in children as well as in young adults and elders. The clinical manifestations produced by hMPV are indistinguishable from those by common respiratory virus, and can evolve from asymptomatic infection into severe pneumonia. On the other hand, some authors have described cases of bronchial asthma exacerbation associated with hMPV infection. In this work we report a case of a child who presented a severe bronchial asthmatic crisis with a suspected viral associated infection. Immunofluorescence tests yielded negative results for sincitial respiratory virus, adenovirus, a-b influenza virus and parainfluenza 1, 2, 3, virus. In an attempt to detect the presence of hMPV, a RT-PCR was carried out to amplify sequences from both N and F genes. Using this approach, a positive result for hMPV was obtained. To our knowledge, this is the first description of a case of asthma exacerbation associated to hMPV in our region. In addition, these results are similar to previous reports where it was hypothesized that, like RSV, hMPV can trigger a respiratory chronic disease as asthma.

Risk factors for wheezing in a subtropical environment: role of respiratory viruses and allergen sensitization.

BACKGROUND: Risk factors for acute wheezing among children in subtropical areas are largely unknown. OBJECTIVE: To investigate the role of viral infections, allergen sensitization, and exposure to indoor allergens as risk factors for acute wheezing in children 0 to 12 years old. METHODS: One hundred thirty-two children 0 to 12 years of age who sought emergency department care for wheezing and 65 children with no history of wheezing were enrolled in this case-control study. Detection of respiratory syncytial virus antigen, rhinovirus and coronavirus RNA, adenovirus, influenza, and parainfluenza antigens was performed in nasal washes. Total IgE and specific IgE to mites, cockroach, cat, and dog were measured with the CAP system. Major allergens from mites, cockroach, cat, and dog were quantified in dust samples by ELISA. Univariate and multivariate analyses were performed by logistic regression. RESULTS: In children under 2 years of age, infection with respiratory viruses and family history of allergy were independently associated with wheezing (odds ratio, 15.5 and 4.2; P = .0001 and P = .008, respectively). Among children 2 to 12 years old, sensitization to inhalant allergens was the major risk factor for wheezing (odds ratio, 2.7; P = .03). High-level allergen exposure, exposure to tobacco smoke, and lack of breast-feeding showed no association with wheezing. CONCLUSIONS: Some risk factors for wheezing previously identified in temperate climates were present in a subtropical area, including respiratory syncytial virus infection in infants and allergy in children older than 2 years. Rhinovirus was not associated with wheezing and did not appear to be a trigger for asthma exacerbations.

Detection of influenza, parainfluenza, adenovirus and respiratory syncytial virus during asthma attacks in children older than 2 years old.

BACKGROUND: Viral upper respiratory tract infections (URTI) have been correlated with the onset of asthma attacks in children and viral identification was reported in 14-49 % of nasal samples. The aim of the present study was to detect influenza, parainfluenza, adenovirus and respiratory syncytial virus (RSV) in older children during acute asthma attacks. METHODS: A total of 104 children (2-14 years) were included in four groups: group I: asthmatics with acute attack and URTI; group II: asthmatics without URTI (group I children, 30 days later); group III: non-asthmatics with URTI; group IV: non-asthmatic, asymptomatic children. A diagnosis of URTI was considered when (3 symptoms (cough and/or sneeze, nasal obstruction, hypertrophy of turbinates, pain and/or retropharynx hyperemia, headache and fever) in asthmatics and at least 2 symptoms in non-asthmatics were present, starting within 7 days. Samples of nasal mucosa cells (n = 123) were collected, and culture and indirect immunofluorescence were carried out to identify respiratory syncytial virus, adenovirus, influenza A and B, parainfluenza 1,2 and 3 and rhinovirus. RESULTS: Viral identification rates were higher in the asthmatic groups: 13.9 % in group I, 11.1 % in group II; 2.8 % in group III and 0 in group IV. The following viruses were identified: RSV 2/36, rhinovirus 1/36, adenovirus 1/36 and parainfluenzae 1/36 in group I; adenovirus 2/18 in group II; RSV 1/36 in group III. CONCLUSIONS: The rate of viral identification was higher in asthmatic children, whether symptomatic or not, suggesting a possible susceptibility to viral infections. Virus could also be a triggering factor in attacks, although it is not the most preponderant in older children.

Viruses and asthma: Inception, exacerbation, and possible prevention.

Viral respiratory tract infections have been epidemiologically associated with asthma in at least 3 ways. First, during infancy, certain viruses have been implicated in the inception of the asthmatic phenotype. Second, in patients with established asthma, particularly children, viral upper respiratory tract infections play a significant role in producing acute exacerbations of airway obstruction, often resulting in outpatient visits or hospitalizations. This increased propensity of viral infections to produce lower airway symptoms in asthmatic persons may be related, at least in part, to interactions among allergic sensitization, allergen exposure, and viral infections-all acting as cofactors in the induction of acute episodes of airflow obstruction. Third, and perhaps counterintuitively, certain infections may actually prevent the development of allergic respiratory tract diseases, including asthma. This review discusses these associations as they pertain to both the pathogenesis and treatment of childhood asthma.

Mechanisms of virus-induced asthma.

In children and adults with asthma, infections with common cold viruses such as respiratory syncytial virus and rhinovirus frequently cause exacerbations of asthma. Recent studies suggest that these and other respiratory viruses infect the lower airways, and that the infected epithelial cells help to initiate immune responses to the virus. These immune responses have antiviral effects, but also enhance airway inflammation and may add to cold symptoms and airway obstruction. Moreover, there are data to suggest that there may be specific interactions between allergic and virus-induced inflammatory responses that contribute to lower airway dysfunction in asthma. Finally, impaired T-helper type 1-like lymphocyte responses during viral infections may be a risk factor for more severe viral illnesses in patients with allergies and asthma. It is hoped that these advances in our understanding of the relationship between viral infections and exacerbations of asthma will translate into new therapeutic targets for virus-induced exacerbations of asthma.