Cause Of Acute Respiratory Infections Research Articles

Streptococcus pneumoniae colonization of the nasopharynx is associated with increased severity during respiratory syncytial virus infection in young children.

ABSTRACTBackground and ObjectiveRespiratory syncytial virus (RSV) is the most significant cause of acute respiratory infection (ARI) in early life. RSV and other respiratory viruses are known to stimulate substantial outgrowth of potentially pathogenic bacteria in the upper airways of young children. However, the clinical significance of interactions between viruses and bacteria is currently unclear. The present study aimed to clarify the effect of viral and bacterial co‐detections on disease severity during paediatric ARI.MethodsNasopharyngeal aspirates from children under 2 years of age presenting with ARI to the emergency department were screened by quantitative PCR for 17 respiratory viruses and the bacterial pathogens Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. Associations between pathogen detection and clinical measures of disease severity were investigated.Results RSV was the most common virus detected, present in 29 of 58 samples from children with ARI (50%). Detection of S. pneumoniae was significantly more frequent during RSV infections compared to other respiratory viruses (adjusted effect size: 1.8, P: 0.03), and co‐detection of both pathogens was associated with higher clinical disease severity scores (adjusted effect size: 1.2, P: 0.03).ConclusionCo‐detection of RSV and S. pneumoniae in the nasopharynx was associated with more severe ARI, suggesting that S. pneumoniae colonization plays a pathogenic role in young children.

Deep sequencing of RSV from an adult challenge study and from naturally infected infants reveals heterogeneous diversification dynamics

As RNA virus mutation occurs during replication within host cells, we hypothesized that viral evolution during acute infections in healthy hosts reflects host immune pressure. We therefore investigated the within-host diversification of human respiratory syncytial virus (RSV), a highly prevalent cause of acute respiratory infections. We evaluated healthy adults experimentally infected with an identical inoculum and infants hospitalized with naturally acquired infections. In aggregate, viral diversification in adults peaked at day 3, with overrepresentation of diversity in the matrix protein 2 (M2) and non-structural protein 2 (NS2) genes. In one subject, delayed viral clearance was accompanied by a late peak of diversity at day 10 in known and predicted B and T cell epitopes. In contrast, infant infections showed much less viral diversity. Our findings suggest multiple overlapping mechanisms for early control of acute viral infections, which may differ between age groups and host immune responses.

Evaluation of the expression level of 12/15 lipoxygenase and the related inflammatory factors (CCL5, CCL3) in respiratory syncytial virus infection in mice model.

Human respiratory syncytial virus (RSV) is a leading cause of acute respiratory infection during early childhood and imposes a great burden on patients, parents, and society. Disease is thought to be caused, at least partially, by an excessive immune response. Pulmonary leukocyte infiltration is the result of a coordinated expression of diverse chemokines with distinct cellular specificities. Lipoxygenases (LOXs), as a key enzyme catalyzing deoxygenation of poly unsaturated fatty acids, regulate inflammation and have been suggested to play an important role in the immune response in viral infection. To expand our understanding on the possible role of LOX in respiratory viral infection, we studied the 12/15- lipoxygenase expression in RSV-related airway inflammation, and the related inflammatory chemokines, Chemokine (C-C motif) ligand 5 (CCL5) and Chemokine (C-C motif) ligand 3(CC L3) in both lung tissue and Bronchoalveolar lavage (BAL) fluid during experimental RSV infection. RSV infection induced mRNA expression of CCL5 and CCL3 in both BAL and lung tissue cells. In addition RSV infection enhanced expression of 12/15-LOX in both BAL and lung cells. In conclusion, we confirm that RSV infection leads to the increased expression of 12/15 LOX and the related chemokines CCL5 and CCL3 in BAL fluid and lung tissue cells suggesting that the 12/15 LOX pathway could serve as a candidate target for prevention and treatment of RSV infection.

RSV N-nanorings fused to palivizumab-targeted neutralizing epitope as a nanoparticle RSV vaccine

Respiratory syncytial virus (RSV) is the leading cause of acute respiratory infections in children, yet no vaccine is available. The sole licensed preventive treatment against RSV is composed of a monoclonal neutralizing antibody (palivizumab), which targets a conformational epitope located on the fusion protein (F). Palivizumab reduces the burden of bronchiolitis but does not prevent infection. Thus, the development of RSV vaccines remains a priority. We previously evaluated nanorings formed by RSV nucleoprotein (N) as an RSV vaccine, as well as an immunostimulatory carrier for heterologous antigens. Here, we linked the palivizumab-targeted epitope (called FsII) to N, to generate N-FsII-nanorings. Intranasal N-FsII immunization elicited anti-F antibodies in mice that were non-neutralizing in vitro. Nevertheless, RSV-challenged animals were better protected against virus replication than mice immunized with N-nanorings, especially in the upper airways. In conclusion, an N-FsII–focused vaccine is an attractive candidate combining N-specific cellular immunity and F-specific antibodies for protection.

Detection of Human Metapneumovirus and Respiratory Syncytial Virus by Real-Time Polymerase Chain Reaction Among Hospitalized Young Children in Iran.

BackgroundAcute respiratory infection plays an important role in hospitalization of children in developing countries; detection of viral causes in such infections is very important. The respiratory syncytial virus (RSV) is the most common etiological agent of viral lower respiratory tract infection in children, and human metapneumovirus (hMPV) is associated with both upper and lower respiratory tract infections among infants and children.ObjectivesThis study evaluated the frequency and seasonal prevalence of hMPV and RSV in hospitalized children under the age of five, who were admitted to Aliasghar children’s hospital of Iran University of Medical Sciences from March 2010 until March 2013.Patients and MethodsNasopharyngeal or throat swabs from 158 hospitalized children with fever and respiratory distress were evaluated for RSV and hMPV RNA by the real-time polymerase chain reaction (PCR) method.ResultsAmong the 158 children evaluated in this study, 49 individuals (31.1%) had RSV infection while nine individuals (5.7%) had hMPV infection. Five (55.5%) of the hMPV-infected children were male while four (44.5%) were female and 27 (55.2%) of the RSV-infected patients were females and 22 (44.8%) were males. The RSV infections were detected in mainly < one year old children and hMPV infections were detected mainly in > one year old children. Both RSV and hMPV infections had occurred mainly during winter and spring seasons.ConclusionsRespiratory syncytial virus was the major cause of acute respiratory infection in children under one-year of age while human metapneumovirus had a low prevalence in this group. The seasonal occurrence of both viruses was the same.

Viral Agents Causing Acute Respiratory Infections in Children under Five: A Study from Eastern India.

Background. Acute respiratory infections (ARIs) are important cause of mortality and morbidity in children under five in developing country. Methods. This observational study was conducted over two-year period in a tertiary care teaching hospital of Eastern India. Nasal and throat swabs were collected, transported to the laboratory at 2–8°C in viral transport media, and then processed for detection of viruses using mono/multiplex real-time polymerase chain reaction. Results. A total of 300 children aged 2–60 months with ARIs were included. The most common age group affected with LRI was 2–12 mo and with URI was >12–60 mo. Viruses were detected in 248 cases. In URI, 77 were positive for single virus and 19 were positive for more than one virus; in LRI, 113 were positive for single virus and 12 were positive for more than one virus. The most common viruses isolated from URI cases were rhinovirus and adenovirus. The most common viruses isolated from LRI cases were respiratory syncytial virus and influenza virus. Most cases occurred in the months of January, December, and August. Conclusion. Viruses constitute a significant cause of ARI in children under five. RSV, ADV, RV, and IFV were the most prevalent viruses isolated.

Experimental evidence and molecular modeling of the interaction between hRSV-NS1 and quercetin

Human Respiratory Syncytial Virus is one of the major causes of acute respiratory infections in children, causing bronchiolitis and pneumonia. Non-Structural Protein 1 (NS1) is involved in immune system evasion, a process that contributes to the success of hRSV replication. This protein can act by inhibiting or neutralizing several steps of interferon pathway, as well as by silencing the hRSV ribonucleoproteic complex. There is evidence that quercetin can reduce the infection and/or replication of several viruses, including RSV. The aims of this study include the expression and purification of the NS1 protein besides experimental and computational assays of the NS1-quercetin interaction. CD analysis showed that NS1 secondary structure composition is 30% alpha-helix, 21% beta-sheet, 23% turn and 26% random coils. The melting temperature obtained through DSC analysis was around 56°C. FRET analysis showed a distance of approximately 19Å between the NS1 and quercetin. Fluorescence titration results showed that the dissociation constant of the NS1-quercetin interaction was around 10−6M. In thermodynamic analysis, the enthalpy and entropy balanced forces indicated that the NS1-quercetin interaction presented both hydrophobic and electrostatic contributions. The computational results from the molecular modeling for NS1 structure and molecular docking regarding its interaction with quercetin corroborate the experimental data.

Rhinovirus-C detection in children presenting with acute respiratory infection to hospital in Brazil.

Human rhinovirus (RV) is a common cause of acute respiratory infection (ARI) in children. We aimed to characterize the clinical and demographic features associated with different RV species detected in children attending hospital with ARI, from low‐income families in North‐east Brazil. Nasopharyngeal aspirates were collected from 630 children <5 years with ARI. Clinical diagnosis and disease severity were also recorded. Samples were analyzed by multiplex PCR for 18 viral and atypical bacterial pathogens; RV positive samples underwent partial sequencing to determine species and type. RV was the fourth commonest pathogen accounting for 18.7% of pathogens detected. RV was commonly detected in children with bronchiolitis, pneumonia, and asthma/episodic viral wheeze (EVW). Species and type were assigned in 112 cases (73% RV‐A; 27% RV‐C; 0% RV‐B). Generally, there were no differences in clinical or demographic characteristics between those infected with RV‐A and RV‐C. However, in children with asthma/EVW, RV‐C was detected relatively more frequently than RV‐A (23% vs. 5%; P = 0.04). Our findings highlight RV as a potentially important pathogen in this setting. Generally, clinical and demographic features were similar in children in whom RV‐A and C species were detected. However, RV‐C was more frequently found in children with asthma/EVW than RV‐A. J. Med. Virol. 88:58–63, 2016. © 2015 Wiley Periodicals, Inc.

Parainfluenza Virus Types 1, 2, and 3 in Pediatric Patients with Acute Respiratory Infections in Beijing During 2004 to 2012.

Background:Although human parainfluenza virus (HPIV) has been determined as an important viral cause of acute respiratory infections (ARIs) in infants and young children, data on long-term investigation are still lacking to disclose the infection pattern of HPIV in China.Methods:Nasopharyngeal aspirates were collected from 25,773 hospitalized pediatric patients with ARIs from January 2004 through December 2012 for respiratory virus screen by direct immuno-fluorescence assay.Results:Out of these specimens, 1675 (6.50%, 1675/25,773) showed HPIV positive, including 261 (1.01%, 261/25,773) for HPIV1, 28 (0.11%, 28/25,773) for HPIV2, and 1388 (5.39%, 1388/25,773) for HPIV3, 2 of the samples were positive for both HPIV1 and HPIV3, and 36 were co-detected with other viruses. The positive rates of HPIVs were higher in those younger than 3 years old. HPIV3 was detected from all age groups, predominantly from patients under 3 years of age, and the highest frequency was found in those 6 months to 1-year old (352/4077, 8.63%). HPIV3 was the dominant type in each of the years detected between May and July. HPIV1 showed a peak in every odd year, mainly in August or September. HPIV was detected most frequently from patients with upper respiratory infection (12.49%, 157/1257), followed by bronchitis (11.13%, 176/2479), asthma (9.31%, 43/462), bronchiolitis (5.91%, 150/2536), pneumonia (6.06%, 1034/17,068), and those with underlying diseases (1.0%, 15/1506). HPIV3 is the dominant type in these six disease groups referred above, especially in the asthma group.Conclusions:HPIV is one of the important viral causes of ARIs in infants and young children in Beijing based on the data from the hospitalized children covering a 9-year term. HPIV3 is the predominant type in all these years and in most of the disease groups. HPIVs with different types show different seasonality.

Prevalence of human respiratory syncytial virus circulating in Iran.

Respiratory syncytial virus (RSV) is a leading cause of acute respiratory infection during early childhood and is associated with a great burden on patients, parents, and society. While no treatment is yet available, results from recent phase 2 clinical trials of cell-entry inhibitors and RSV vaccines are promising. To prepare for introduction of these novel therapeutics, good understanding of its molecular epidemiology and continuous RSV surveillance data are necessary. This paper provides an overview of RSV prevalence and genotype distribution in Iran from 1996 to 2013. This meta-analysis includes 21 published studies. In total, 775 (18.7%) of 4140 respiratory specimens were positive for RSV infection. The male-female ratio of RSV-positive patients was 1.5:1. Significant peaks of RSV infection were detected during the cold season (November-March). RSV infection was mainly observed in patients <2 years of age. Phylogenetic studies showed that genotypes GA1, GA2, GA5, and BA co-circulated in Iran in 2007-2013. This review highlights the necessity of introducing standard molecular surveillance programs to inform the epidemiological, clinical, and pathological characteristics of various RSV genotypes. Improved understanding of the molecular epidemiology will be useful for development of novel RSV therapeutics.

Parainfluenza virus as a cause of acute respiratory infection in hospitalized children

BackgroundHuman parainfluenza viruses account for a significant proportion of lower respiratory tract infections in children. ObjectiveTo assess the prevalence of Human parainfluenza viruses as a cause of acute respiratory infection and to compare clinical data for this infection against those of the human respiratory syncytial virus. MethodsA prospective study in children younger than five years with acute respiratory infection was conducted. Detection of respiratory viruses in nasopharyngeal aspirate samples was performed using the indirect immunofluorescence reaction. Length of hospital stay, age, clinical history and physical exam, clinical diagnoses, and evolution (admission to Intensive Care Unit or general ward, discharge or death) were assessed. Past personal (premature birth and cardiopathy) as well as family (smoking and atopy) medical factors were also assessed. ResultsA total of 585 patients were included with a median age of 7.9 months and median hospital stay of six days. No difference between the HRSV+ and HPIV+ groups was found in terms of age, gender or length of hospital stay. The HRSV+ group had more fever and cough. Need for admission to the Intensive Care Unit was similar for both groups but more deaths were recorded in the HPIV+ group. The occurrence of parainfluenza peaked during the autumn in the first two years of the study. ConclusionParainfluenza was responsible for significant morbidity, proving to be the second-most prevalent viral agent in this population after respiratory syncytial virus. No difference in clinical presentation was found between the two groups, but mortality was higher in the HPIV+ group.

Molecular epidemiology of enterovirus D68 from 2013 to 2014 in Philippines.

Enterovirus D68 (EV-D68) has been recognized as an important cause of acute respiratory infections. Here we report the molecular epidemiology of EV-D68 in Philippines from 2013 to 2014; we found cases in areas affected by Typhoon Haiyan and found new strains in the country.

Respiratory tract infections in the military environment

Military personnel fighting in contemporary battlefields as well as those participating in combat training are at risk of contracting respiratory infections. Epidemiological studies have demonstrated that soldiers deployed to the harsh environment have higher rates of newly reported respiratory symptoms than non-deployers. Acute respiratory diseases are the principle reason for outpatient treatment and hospitalization among military personnel, with an incidence exceeding that of the adult civilian population by up to three-fold. Adenoviruses, influenza A and B viruses, Streptococcus pneumoniae, Streptococcus pyogenes, coronaviruses and rhinoviruses have been identified as the main causes of acute respiratory infections among the military population. Although infective pathogens have been extensively studied, a significant proportion of illnesses (over 40%) have been due to unknown causative agents. Other health hazards, which can lead to respiratory illnesses among troops, are extreme air temperatures, desert dust, emissions from burn pits, industrial pollutants, and airborne contaminants originating from degraded soil. Limited diagnostic capabilities, especially inside the area of operations, make it difficult to accurately estimate the exact number of respiratory diseases in the military environment. The aim of the study was to discuss the occurrence of respiratory tract infections in army personnel, existing risk factors and preventive measures.

Influenza-like illness sentinel surveillance in one hospital in Medellin, Colombia. 2007-2012.

BackgroundThe city of Medellin in Colombia has almost no documentation of the causes of acute respiratory infections (ARIs). As part of an ongoing collaboration, we conducted an epidemiologic surveillance for influenza and other respiratory viruses. It described the influenza strains that were circulating in the region along with their distribution over time, and performing molecular characterization to some of those strains. This will contribute to the knowledge of local and national epidemiology.ObjectivesTo analyze viral etiologic agents associated with influenza like illness (ILI) in participants reporting to one General hospital in Medelllin, Colombia.ResultsFrom January 2007 to December 2012, a total of 2039 participants were enrolled. Among them, 1120 (54·9%) were male and 1364 (69%) were under the age of five. Only 124 (6%) were older than the age of 15. From all 2039 participants, 1040 samples were diagnosed by either isolation or RT-PCR. One or more respiratory viruses were found in 737 (36%) participants. Of those, 426 (57·8%) got influenza A or B. Adenoviral and parainfluenza infections represented 19·1% and 14·9% of viral infections, respectively. Influenza A was detected almost throughout the whole year except for the first quarter of 2010, right after the 2009 influenza A pandemic. Influenza B was detected in 2008, 2010, and 2012 with no pattern detected. During 2008 and 2010, both types circulated in about the same proportion. Unusually, in many months of 2012, the proportion of influenza B infections was higher than influenza A (ranging between 30% and 42%). The higher proportion of adenovirus was mainly detected in the last quarter of years 2007 and 2010. Adenoviral cases are more frequent in participants under the age of four.ConclusionsThe phylogenetic analysis of influenza viruses shows that only in the case of influenza A/H1N1, the circulating strains totally coincide with the vaccine strains each year.

Human Metapneumovirus Virus-Like Particles Induce Protective B and T Cell Responses in a Mouse Model

Human metapneumovirus (HMPV) is a leading cause of respiratory disease in infants, children, and the elderly worldwide, yet no licensed vaccines exist. Live-attenuated vaccines present safety challenges, and protein subunit vaccines induce primarily antibody responses. Virus-like particles (VLPs) are an attractive alternative vaccine approach because of reduced safety concerns compared with live vaccines. We generated HMPV VLPs by expressing viral proteins in suspension-adapted human embryonic kidney epithelial (293-F) cells and found that the viral matrix (M) and fusion (F) proteins were sufficient to form VLPs. We previously reported that the VLPs resemble virus morphology and incorporate fusion-competent F protein (R. G. Cox, S. B. Livesay, M. Johnson, M. D. Ohi, and J. V. Williams, J. Virol. 86:12148-12160, 2012), which we hypothesized would elicit F-specific antibody and T cell responses. In this study, we tested whether VLP immunization could induce protective immunity to HMPV by using a mouse model. C57BL/6 mice were injected twice intraperitoneally with VLPs alone or with adjuvant and subsequently challenged with HMPV. Mice were euthanized 5 days postinfection, and virus titers, levels of neutralizing antibodies, and numbers of CD3(+) T cells were quantified. Mice immunized with VLPs mounted an F-specific antibody response and generated CD8(+) T cells recognizing an F protein-derived epitope. VLP immunization induced a neutralizing-antibody response that was enhanced by the addition of either TiterMax Gold or α-galactosylceramide adjuvant, though adjuvant reduced cellular immune responses. Two doses of VLPs conferred complete protection from HMPV replication in the lungs of mice and were not associated with a Th2-skewed cytokine response. These results suggest that nonreplicating VLPs are a promising vaccine candidate for HMPV. Human metapneumovirus (HMPV) is a leading cause of acute respiratory infection in infants, children, and the elderly worldwide, yet no licensed vaccines exist. Live-attenuated vaccines present safety challenges, and protein subunit vaccines induce primarily antibody responses. Virus-like particles (VLPs) are an attractive alternative vaccine approach. We generated HMPV VLPs by expressing the viral matrix (M) and fusion (F) proteins in mammalian cells. We found that mice immunized with VLPs mounted an F-specific antibody response and generated CD8(+) T cells recognizing an F protein-derived epitope. VLP immunization induced a neutralizing-antibody response that was enhanced by the addition of either TiterMax Gold or α-galactosylceramide adjuvant. Two doses of VLPs conferred complete protection against HMPV replication in the lungs of mice and were not associated with a Th2-skewed cytokine response. These results suggest that nonreplicating VLPs are a promising vaccine candidate for HMPV.

Prophylactic antibody treatment and intramuscular immunization reduce infectious human rhinovirus 16 load in the lower respiratory tract of challenged cotton rats

Human rhinoviruses (HRV) represent the single most important etiological agents of the common cold and are the most frequent cause of acute respiratory infections in humans. Currently the performance of available animal models for immunization studies using HRV challenge is very limited. The cotton rat (Sigmodon hispidus) is a well-recognized model for the study of human respiratory viral infections. In this work we show that, without requiring any genetic modification of either the host or the virus, intranasal infection of cotton rats with HRV16 resulted in measurable isolation of infective virus, lower respiratory tract pathology, mucus production, and expression of interferon-activated genes. Intramuscular immunization with live HRV16 generated robust protective immunity that correlated with high serum levels of neutralizing antibodies. In addition, cotton rats treated prophylactically with hyperimmune anti-HRV16 serum were protected against HRV16 intranasal challenge. Finally, protection by immunization was efficiently transferred from mothers to newborn animals resulting in a substantial reduction of infectious virus loads in the lung following intranasal challenge. Overall, our results demonstrate that the cotton rat provides valuable additional model development options for testing vaccines and prophylactic therapies against rhinovirus infection.

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

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

Monoclonal antibody for reducing the risk of respiratory syncytial virus infection in children

Monoclonal antibody for reducing the risk of respiratory syncytial virus infection in children

Identification of Recombinant Human Rhinovirus A and C in Circulating Strains from Upper and Lower Respiratory Infections

Human rhinoviruses (HRVs), in the Enterovirus genus within the family Picornaviridae, are a highly prevalent cause of acute respiratory infection (ARI). Enteroviruses are genetically highly variable, and recombination between serotypes is known to be a major contribution to their diversity. Recently it was reported that recombination events in HRVs cause the diversity of HRV-C. This study analyzed parts of the viral genes spanning the 5′ non- coding region (NCR) through to the viral protein (VP) encoding sequences of 105 HRV field isolates from 51 outpatient cases of Acute Respiratory Infectious Network (ARINET) and 54 inpatient cases of severe lower respiratory infection (SLRI) surveillance, in order to identify recombination in field samples. When analyzing parts of the 5′NCR and VP4/VP2 encoding sequences, we found intra- and interspecies recombinants in field strains of HRV-A and -C. Nineteen cases of recombination events (18.1%) were found among 105 field strains. For HRV-A, there were five cases (4.8%) of intraspecies recombination events and three cases (2.8%) of interspecies recombination events. For HRV-C, there were four cases (3.8%) of intraspecies recombination events and seven cases (6.7%) of interspecies recombination events. Recombination events were significantly more frequently observed in the ARINET samples (18 cases) than in the SLRI samples (1 case; P< 0.0001). The recombination breakpoints were located in nucleotides (nt) 472–554, which comprise stem-loop 5 in the internal ribosomal entry site (IRES), based on the HRV-B 35 sequence (accession no. FJ445187). Our findings regarding genomic recombination in circulating HRV-A and -C strains suggest that recombination might play a role in HRV fitness and could be a possible determinant of disease severity caused by various HRV infections in patients with ARI.

Viral causes of acute respiratory infection among Egyptian children hospitalized with severe acute asthma exacerbation

Viral respiratory infections are associated with nearly 80% of asthma exacerbation episodes. These can have severe adverse outcomes in patients with established asthma. The aim of the study was to identify the viral causes of acute respiratory infection that precipitate acute asthma exacerbation in Egyptian asthmatic children. The current prospective study was conducted in Cairo University Children's Hospitals from December 2010 to December 2011. All asthmatic children (n=130) aged 2-12 years admitted with asthma exacerbation due to severe lower respiratory tract infection were included. All cases were subjected to nasopharyngeal or throat swabs that were analyzed for common respiratory viruses, including respiratory syncytial virus (RSV), human metapneumovirus (hMPV), influenza B (Flu B), human parainfluenza virus (hPIV), influenza A (H1N1), and adenovirus (ADV) using the real-time PCR technique. All patients were followed up to record the outcome. PCR analysis was positive for one respiratory virus in 54 asthmatic patients (41.5%) and was negative in 76 patients (58.5%), with a high predominance of RSV (51.9%) and hMPV (25.9%) especially in winter and early spring months. Hypoxia was detected in all patients with RSV infection; of these patients, 21.4% were admitted to the ICU, 14.3% required mechanical ventilation, and 14.3% died. In contrast, among those with hMPV infection, hypoxia was detected in 71.4%; none required ICU admission or mechanical ventilation. Viral etiology of lower respiratory tract infections constitutes an important cause of acute asthma exacerbation in asthmatic children admitted to children's hospitals in Cairo, supporting the need for large-scale multicentric studies on asthmatic patients over multiple years using a wider-panel PCR for detection of respiratory viruses.