Viral aetiology of lower respiratory tract infection in young Malaysian children

OBJECTIVE: To study the viral aetiology of lower respiratory tract infection (LRTI) in young Malaysian children. METHODOLOGY: A retrospective review was performed of LRTI patients aged less than 24 months who were admitted to the University Malaya Medical Centre between 1982 and 1997. Respiratory viruses in their nasopharyngeal secretion were identified by indirect immunofluorescence, viral culture, or both. RESULTS: A total of 5691 children were included in the study. The mean age was 8.6 +/- 6.6 months and the M:F ratio was 1.6:1. The most common diagnosis was pneumonia (52%) followed by bronchiolitis (45%) and croup (2%). Positive viral isolation rate was 22.0%. Respiratory syncytial virus (RSV) was the commonest virus isolated (84%), followed by parainfluenza virus (8%), influenza virus (6%) and adenovirus (2%). Patients with positive virus isolation were younger (7.8 +/- 6.2 vs 8.7 +/- 6.7 months, P = 0.0001) and were more likely to have bronchiolitis. CONCLUSION: Young Malaysian children admitted with LRTI had a 22% viral isolation rate and RSV was the commonest virus isolated.     

Respiratory syncytial virus infection in patients with phagocyte defects

Patients with phagocyte defects frequently develop bacterial or fungal pneumonias, but they are not considered to be at increased risk for viral infections. We describe 3 patients with known phagocyte immunodeficiencies who developed lower respiratory tract infections (LRTI) caused by respiratory syncytial virus (RSV). All 3 patients had dense pneumonias as indicated by computed tomography scan of the lungs and RSV was recovered. We conclude that RSV can present as a dense pneumonia in patients with phagocyte defects. Along with common pathogens causing LRTI, RSV should be considered in the differential diagnosis. Viral cultures as well as rapid antigen detection assays for respiratory viruses should be included in the evaluation of LRTI in patients with phagocyte defects. respiratory syncytial virus, phagocyte, immunodeficiency, pneumonia.     

Epidemiology of acute respiratory infections in young children from Thailand

A prospective evaluation of the epidemiology and presentations of acute respiratory infections in children younger than 5 years of age admitted to Children's Hospital Bangkok (1988 to 1989) was supported by the World Health Organization. There were 226 patients with the inclusion criteria: 1 to 5 years of age; duration of illness less than 2 weeks; no prior antibiotic therapy; and low socioeconomic status. The disease categories included: croup, 19 cases; bronchiolitis, 60 cases; and pneumonia, 147 cases. Pathogens isolated were: respiratory syncytial virus (40); parainfluenza III (1); influenza B (1); and adenovirus (1); bacterial infections were proved in 23 cases. No significant differences in clinical features between bacterial and viral pneumonia were found. Interstitial radiographic patterns were more common in viral pneumonia whereas alveolar patterns were more common in bacterial pneumonia. However, 91% of mixed radiographic patterns (interstitial and alveolar) in chest films were from viral pneumonia.     

Eleven consecutive years of respiratory syncytial virus outbreaks in Croatia

Background:  Respiratory syncytial virus (RSV) is the most common cause of severe lower respiratory tract infections (LRTI) in infants. The aim of the present study was to analyze the epidemiologic characteristics of RSV outbreaks in Croatian children.
Methods:  Over a period of 11 consecutive years (1994–2005), 3435 inpatients with acute respiratory infections (ARI) aged from birth to 10 years and were residing in Zagreb County were tested for infection with RSV and other respiratory viruses at the Virology Department, Croatian National Institute of Public Health. RSV was identified in nasopharyngeal secretions by isolation on cell culture and/or detection with monoclonal antibodies using a direct fluorescence assay.
Results:  RSV was the most common causative agent of ARI (42.2%; 658/1559) for the infants 0–6 months of age. It was also the etiologic agent of LRTI in 49% (495/1010) of infants of similar age. RSV was demonstrated in 56.5% (382/676) of infants with bronchiolitis, and in 36.5% (49/134) of those with pneumonia in this age group.
Conclusion:  The overall prevalence of RSV infection in Croatian children with acute respiratory illness, and its occurrence in various age groups, has remained stable over the past decade. RSV was found to be the most common cause of bronchiolitis occurring throughout childhood (52.7%; 482/913).     

Association between multiple respiratory viral infections and pediatric intensive care unit admission among infants with bronchiolitis

BackgroundIt is unclear whether multiple respiratory viral infections are associated with more severe bronchiolitis requiring pediatric intensive care unit (PICU) admission. We aimed to identify the association between multiple respiratory viral infections and PICU admission among infants with bronchiolitis.MethodsWe performed a 1:1 case-control study enrolling previously healthy full-term infants (≤12 months) with bronchiolitis admitted to the PICU as cases and those to the general pediatric ward as controls from 2015 to 2017. Multiplex polymerase chain reaction (PCR) was used for detection of the respiratory viruses. We summarized the characteristics of infants admitted to the PICU and the general pediatric unit. Multivariable logistic regression analysis was used to fit the association between multiple respiratory viral infections (≥2 strains) and PICU admission.ResultsA total of 135 infants admitted to the PICU were compared with 135 randomly selected control infants admitted to the general pediatric unit. The PICU patients were younger (median: 2.2 months, interquartile range: 1.3–4.2) than the general ward patients (median: 3.2 months, interquartile range: 1.6–6.4). Respiratory syncytial virus (74.1%), rhinovirus (28.9%), and coronavirus (5.9%) were the most common viruses for bronchiolitis requiring PICU admission. Patients with bronchiolitis admitted to the PICU tended to have multiple viral infections compared with patients on the general ward (23.0% vs. 10.4%, P < 0.001). In the multivariable logistic regression analysis, bronchiolitis with multiple viral infections was associated with higher odds of PICU admission (adjusted odds ratio: 2.56, 95% confidence interval: 1.17–5.57, P = 0.02).ConclusionInfants with multiviral bronchiolitis have higher odds of PICU admission compared with those with a single or nondetectable viral infection.     

The impact of dual viral infection in infants admitted to a pediatric intensive care unit associated with severe bronchiolitis

INTRODUCTION: Bronchiolitis is a major cause of morbidity and mortality in early childhood worldwide. The presence of more than one pathogen may influence the natural history of acute bronchiolitis in infants. OBJECTIVE: To investigate the relevance of dual viral infection in infants with severe bronchiolitis hospitalized in a short-term unit compared with those in a pediatric intensive care unit (PICU). STUDY DESIGN: One hundred eighty infants <1 year old hospitalized with bronchiolitis in a short-term unit (n = 92) or admitted to the PICU (n = 88) during 2 consecutive winter seasons 2003/2004 and 2004/2005 were evaluated. Molecular biology and standard methods were used to diagnose human respiratory viruses in nasal/throat swabs and nasal aspirates. Clinical data related to host factors and viral prevalence were compared among infants requiring or not PICU support. RESULTS: A viral agent was identified in 96.1% of infants with bronchiolitis. Respiratory syncytial virus (70.6% and 73.6%, respectively in the short-term unit and PICU) and rhinovirus (18.5% and 25.3%, respectively in the short-term unit and PICU) were the main detected respiratory viruses in infants hospitalized in both units. No significant difference in viral prevalence was observed between the populations studied. From multivariate analysis, infants with coinfections were 2.7 times (95% CI: 1.2-6.2) more at risk for PICU admission than those with a single infection. Respiratory syncytial virus and rhinovirus were the viruses most frequently identified in mixed infections in infants hospitalized with bronchiolitis. CONCLUSIONS: Dual viral infection is a relevant risk factor for the admission of infants with severe bronchiolitis to the PICU.     

Bronchiolitis in tropical south India

In a prospective hospital-based study of 328 children under 5 years of age with acute lower respiratory infections, 114 (35%) were diagnosed to have acute bronchiolitis. Of them, 87 (76%) were less than 1 year and 107 (94%) were less than 2 years of age. Signs of severe lower respiratory infections, namely tachypnea (respiratory rate greater than 50/min) and subcostal retraction, were present in 95% and 93%, respectively. Of 88 children of whom roentgenographs were taken, 30 (34%) had evidence of pneumonia. No clinical signs discriminated between those with and without pneumonia. By culture or immunofluorescence antigen detection, viruses were found in 81 (71%) children with bronchiolitis; respiratory syncytial virus was the most common agent, found in 65 (57%). Parainfluenza viruses were the next most common, found in 12 (11%). Most cases of bronchiolitis occurred in outbreaks during the rainy months of August through November, coinciding with respiratory syncytial virus outbreaks. Although bacterial culture of blood was done in 56 children, no respiratory pathogen was isolated. In one child with bronchiolitis and consolidation, postmortem lung aspirate yielded Staphylococcus aureus. Thus, bronchiolitis is primarily a viral syndrome in this tropical region, just as it is in temperate regions. Eight (7%) children died (all were infants); 5 had roentgenographic pneumonia and the remaining had other abnormalities contributing to death; all had been treated with antibiotics. Since one third of lower respiratory infections are bronchiolitis, and among infants under 1 year of age bronchiolitis comprises 47% of all lower respiratory infection cases, criteria for antibiotic management must take into account the availability of roentgenographic investigation.     

Viral infections in hospitalized children affected by acute lower respiratory tract disease

OBJECTIVE: To evaluate the frequency of the main respiratory viruses in hospitalized children affected by acute lower respiratory tract disease at a university hospital. METHODS: This is a prospective trial that included two cohorts of hospitalized children in the period from April to July 1996. The groups were selected according to the presence of lower respiratory tract disease on admission: Group A- with acute disease (history of less than 7 days) and B- without present or recent respiratory disease. The parameters for defining lower respiratory tract disease included physical and/or radiological pulmonary changes. Clinical and radiological criteria were established for the classification of lower respiratory tract diseases in group A. Nasopharyngeal swab was collected from all children on admission for viral detection by cellular cultures and direct immunofluorescence. RESULTS: 201 cases were selected, 126 in group A and 75 in group B. Viruses were identified in 71 children from groupA(56.4%) and only in 3 from group B (4.0%). The predominant agent in group A was respiratory syncytial virus, identified in 66 cases; adenovirus (4) and influenza (1) were detected in other patients. In group B two patients with respiratory syncytial virus and one with adenovirus were identified. The patients from group A affected by respiratory syncytial virus were younger (median age 3 months versus 13 months) and more wheezy on physical examination (78.7%) than the other patients of the group (33.3%). This virus was associated to most of the bronchiolitis cases (84%) and to half of the pneumonia cases (46.4%). CONCLUSION: The authors found a significant presence of viruses in the majority of children hospitalized with acute lower respiratory tract disease. The respiratory syncytial virus was the predominant agent identified. These results are similar to others previously reported both in developed and some developing countries. The authors emphasize that the present study evaluated only partially the possibility of simultaneous infection by other pathogens and that the present protocol was conducted during the season with the highest incidence of respiratory syncytial virus.     

Detection of new respiratory viruses in hospitalized infants with bronchiolitis: a three‐year prospective study

Aim: We have designed a study with the objective of describing the clinical impact of other viruses different from the respiratory syncytial virus (RSV) in hospitalized infants with bronchiolitis. Methods: A 3 year prospective study was conducted on infants admitted to the Paediatrics Department of the Severo Ochoa Hospital (Spain). We studied the frequency of 16 respiratory viruses. Clinical characteristics of RSV‐only infections were compared with other single agent viral infections. Results: Positive results were confirmed in 275 (86.5%) of the 318 children studied. A single virus was detected in 196 patients and 79 were dual or multiple viral infections. RSV was detected in 61.3% of total bronchiolitis. Rhinovirus (RV) was 17.4% of the identified virus, followed by human bocavirus (HBoV), adenovirus and metapneumovirus (hMPV). Only RV, HBoV and hMPV were significant as single infections. RSV patients were younger than HBoV (p > 0.0001) and hMPV (p = 0.025). Seasonality was clearly different between them. Children with RSV infection needed treatment in the intensive care unit more frequently than others. Conclusions: In hospitalized infants, RSV was the most frequent agent in bronchiolitis in winter, but other viruses were present in 47% of the patients. RV, HBoV and hMPV had a significant proportion of single infections. Clinical characteristics were similar amongst them, but seasonality was clearly different.     

Differing manifestations of respiratory syncytial virus-associated severe lower respiratory tract infections in human immunodeficiency virus type 1-infected and uninfected children

BACKGROUND: Respiratory syncytial virus (RSV) causes increased morbidity and mortality in immunocompromised children. The outcome of RSV-associated lower respiratory tract infections (LRTI) in HIV-infected children, is less well described. METHODS: Children from a prospective study evaluating the etiology of     

重庆地区婴幼儿重症肺炎呼吸道病毒病原分析

目的 了解重庆地区婴幼儿重症肺炎病毒病原的感染情况.方法 2006年12月至2008年3月,取ICU病房收集诊断为重症肺炎患儿的深部气道或机械通气气管导管内吸取物标本119例,采用RT-PCR或PCR方法 检测呼吸道合胞病毒(RSV)、人偏肺病毒(hMPV)、博卡病毒(HBoV)、腺病毒(ADV)、副流感病毒(PIV)1、2、3和流感病毒(IV)A、B等呼吸道病毒病原.结果 119例标本中病毒总检出例数为86例(72.3%),其中RSV检出率最高,为41.2%(49/119).有2种及以上病毒协同感染23例,占26.7%(23/86);RSV阳性中有19例存在协同感染,占38.8%(19/49).69例行细菌检测,其中53例为阳性,阳性率为76.8%.这69例标本中,病毒阳性率为76.8%;病毒细菌双阳性为41例,占59.4%.结论 (1)病毒感染仍是重庆地区婴幼儿重症肺炎的重要病因.(2)BSV是婴幼儿重症肺炎最常见病毒病原,其次为ADV和hMPV.(3)病毒的协同感染较在重症呼吸道患儿中可能较为普遍,但尚无证据说明病毒协同感染可加重病情.     

Urine leukotriene E4 and eosinophil cationic protein in nasopharyngeal aspiration from young wheezy children

Respiratory syncytial virus (RSV) infection is a risk factor for the development of asthma. It is very hard to distinguish bronchiolitis with respiratory virus infection from allergic asthma at first wheezing attack in early childhood. To distinguish wheezing children with RSV bronchiolitis from asthmatic children, we measured leukotriene E(4)(LTE(4)) in urine and ECP in nasopharyngeal aspiration (NPA) at first day of admission with wheezing attack. Thirty-two non-atopic children younger than the age of 3 yr with RSV induced bronchiolitis, 35 atopic asthmatic children with/without respiratory viral infection, and 23 children who exhibited no evidence of atopy, asthma, or virus infections as controls were selected in this study. We measured urinary LTE(4) and ECP level in NPA from subjects. Urinary LTE(4) concentrations in children with asthma were significantly higher than urinary LTE(4) in bronchiolitis and in controls (240.8 +/- 129.8 vs. 162.8 +/- 73.9 vs. 85.1 +/- 31.6 pg/ml). Children with RSV infection demonstrated higher urinary LTE(4) levels compared to children without RSV infection among asthmatic children. ECP in NPA was significantly correlated with urinary LTE(4) (r = 0.57, p < 0.01) in children entered this study who had detectable levels for both LTE(4) and ECP. In summary, Urinary LTE(4) concentrations may be suggested to useful mediators for differential diagnosis of wheezy diseases in early childhood. RSV infection also is associated with synergizing LT biosynthesis and this study demonstrated ECP in NPA was significantly correlated with urinary LTE(4) and may suggest that cysteinyl leukotriene initiate the production of ECP in early childhood, which could contribute to the development of wheeze.     

Acute lower respiratory infections in hospitalized children over a 6 year period in Tokyo

BACKGROUND: Acute lower respiratory infections are major causes of hospitalization in children and are mainly caused by respiratory viruses. In the present study, we investigated the etiologic agents responsible for acute lower respiratory infections from the period November 1986 to October 1992 in order to determine the seasonal pattern and different characteristics of age distribution of respiratory infectious agents, mainly virus infections. METHODS: A total of 1521 patients with lower respiratory infections was hospitalized in Saiseikai Central Hospital, Tokyo, Japan. Nasopharyngeal secretions were obtained for virus isolation and paired sera in the acute and convalescent phases were obtained for serological examination. RESULTS: Etiological agents were identified in 668 of 1521 patients (43.9%) by serological antibody responses, virus isolation and/or detection of virus antigen: 240 (15.8%) with respiratory syncytial (RS) virus; 62 (4.1%) with influenza virus type A; 26 (1.7%) with influenza virus type B; 86 (5.7%) with adenovirus; 81 (5.3%) with parainfluenza virus; 32 (2.1%) with measles virus; 20 (1.3%) with enteroviruses or Herpes virus other than respiratory viruses; 75 (4.9%) with Mycoplasma pneumoniae; 10 (0.7%) with pertussis; and 36 (2.4%) with mixed infections. In the remaining 853 patients (56.1%), etiologic agents were not identified. Respiratory syncytial (RS) virus was a main causative agent of respiratory infections in patients younger than 3 years of age. Influenza virus and M. pneumoniae were two main causative agents in patients with acute respiratory illness over 5 years of age. Parainfluenza virus type 3 was frequently observed in infants from 9 to 12 months of age. A distinct seasonal pattern of viral infections was consistently observed in each year during the study period; RS and influenza viruses were prevalent in winter, parainfluenza virus was prevalent in spring and M. pneumoniae was prevalent in summer and autumn. However, adenovirus infections were observed in all seasons. Serological responses were poor in patients younger than 1 year of age and they were mainly diagnosed by virus isolation or detection of virus antigen. CONCLUSIONS: Virological epidemiology provides useful information in daily clinical practice for the prediction of etiological agents based on patient age and the seasonal distribution of agents. We should examine virus isolation and the detection of virus antigen, along with serological examinations in patients with respiratory infections, especially in infants younger than 1 year of age because of poor serological responses.     

The burden of respiratory viral disease in hospitalized children in Paris

A virus was identified in 464 out of 1,212 patients, 8 days to 16 years of age, who were admitted to the hospital in Paris during a 3 year period. Respiratory syncytial virus (RSV) was found in 428 patients, 74% were younger than 6 months with bronchiolitis, and 6% were older than 2 years. RSV was the first virus isolated in all patients and in those with pneumonia or asthma. The low number of admissions due to parainfluenzae viruses is characteristic of this area compared to other countries.     

Comparison of cytokine responses in nasopharyngeal aspirates from children with viral lower respiratory tract infections

Aim: To determine whether nasopharyngeal aspirates (NPAs) cytokine response is different according to the causative viruses in children with lower respiratory tract infections (LRTI).
Methods: NPAs from 277 children with LRTI caused by respiratory virus were evaluated. Based on the proven viral agents, LRTI patients were divided into four groups. Levels of IL-4, IL-5 and IFN-γ were determined by ELISA.
Results: Patients with influenza virus infection demonstrated significantly lower IL-4 and IL-5 levels than those with other three groups. Patients with respiratory syncytial virus (RSV) infection showed an increase in production of IL-4 and IL-5, and a decrease in the IFN-γ level when compared to patients with influenza virus infection. Interestingly, a similar Th2 response was seen in patients with parainfluenza virus or adenovirus infection.
Conclusion: These results demonstrate that respiratory viruses can induce different local cytokine responses. However, Th2 biased responses are not unique for RSV but seem to be predominant in respiratory viruses of young children.     

Neutrophil-mediated inflammation in respiratory syncytial viral bronchiolitis

BACKGROUND: The involvement of neutrophil-mediated inflammation may play an important role in the pathogenesis of acute respiratory syncytial virus bronchiolitis. However, no measurable marker is sensitive enough to assess neutrophil-mediated inflammation in the airways. Released neutrophil elastase (NE) in intraluminal airways has been reported to induce pulmonary inflammation. The aim of this study was to determine whether the amount of urinary trypsin inhibitor (UTI) in serum, a degenerate induced by NE, reflects the degree of airway inflammation in children with respiratory syncytial viral (RSV) bronchiolitis and whether the severity of inflammation is evaluated. The pre-alpha-/inter-alpha-trypsin inhibitor is assumed to be precursors of the UTI. When NE degrades these inhibitors, UTI is liberated. METHODS: Serum UTI concentrations in infants admitted with RSV bronchiolitis, other viral infections, bacterial pneumonia and control subjects were measured by means of one-step sandwich-type enzyme immunoassay. RESULTS: Serum UTI concentrations in 25 patients on admission were significantly higher than the 15 infantile control values (mean +/- SEM, 22.126 +/- 2.317 and 6.701 +/- 0.719 U/mL, respectively; P < 0.0001). The elevated levels returned to baseline values with improvement in the respiratory symptoms. Higher levels of serum UTI with RSV infection were consistently associated with clinical symptoms and artificial ventilation. Serum NE concentrations of patients were elevated in some patients but not significantly different from controls in the patients who showed only upper respiratory symptoms with RSV infections. CONCLUSION: The findings strongly suggested that neutrophil-mediated events are involved in the pathogenesis of RSV bronchiolitis, and the monitoring of UTI concentrations might be useful for evaluating the neutrophil-mediated airway inflammation.     

VIRAL INFECTIONS OF THE RESPIRATORY TRACT IN HOSPITALIZED CHILDREN A Study from Oslo during a 90 Months'Period

ABSTRACT. A diagnosis of 979 respiratory viral infections was made in hospitalized children. Respiratory syncytial virus greatly outnumbered the other viruses: it caused 58% of the total virus infections and occurred in winter epidemics. Influenza A and B virus occurred during late winter and spring, rhinovirus had a seasonal distribution towards spring and autumn, whereas adenovirus types 1, 2 and 5 had no distinct seasonal distribution. Whereas respiratory syncytial virus were mainly associated with bronchiolitis and adenovirus type 7 with pneumonia, rhinovirus infections were most often found in children with episodes of acute bronchial asthma. The influenza A and B and adenovirus types 1, 2 and 5 infections often occurred with extrarespiratory symptoms, especially febrile convulsions.     

Respiratory diseases in infants hospitalized during the 1st 2 years of life for viral lower respiratory tract infections: a one-year follow-up

BACKGROUND: Epidemiologic data suggest strong links between hospitalisation with bronchiolitis in infancy and subsequent higher risk of developing lower respiratory tract infections (LRTI) and/or hyperreactive airway diseases. The aim of this study was to evaluate in an Italian population the natural history of respiratory diseases in children hospitalised for LRTI when they were <2 years. METHODS: An observational, perspective, longitudinal study was performed through telephone interviews. Nine pediatric tertiary care centres participated to the study evaluating a population of 187 children, hospitalised in the previous year (November 1999-April 2000) for bronchiolitis or pneumonia when they were <2 years of age and participated to a previous study on the prevalence of infant LRTI in Italy (RADAR). RESULTS: Twenty-three (12.3%) children had a gestational age <36 weeks. In the 12 months following the first hospitalisation, an elevated frequency of respiratory symptoms was found. Indeed, 152 (81.3%) children suffered from not-requiring-hospital-admission respiratory infections and 21 (11.2%) were hospitalized again for LRTI: 11.6% had bronchiolitis, 23.5% bronchitis and 35.2% pneumonia. In addition, 1.2% had gs;3 infectious episodes and 21.4% gs;6: 68 (36.4%) showed wheezy bronchitis and 17 (9.1%) were reported to have asthma; 132 children (71%) took antibiotics during the last year, 19.4% >3 times; 111 (59.4%) bronchodilators and 49 (26.2%) oral corticosteroids. One year after the first hospitalisation, 19 subjects (10.2%) were found to be positive to at least one class of allergens by prick test or RAST. CONCLUSIONS: Thus, the demonstration of a high morbidity rate for LRTI, wheezing and asthma in this study group during the first year follow-up after hospital admission further support the need for prophylactic interventions to reduce the morbidity and severity of sequelae of LRTI, in particularly in premature children and/or with additional risk factors.     

Respiratory viral infections in children with leukemia

BACKGROUND: Respiratory viruses occur frequently in the community and are a common cause of fever in children. Data on respiratory viral infections in children with cancer are limited. METHODS: A long-term, prospective, multicenter study was carried out in Finland searching for respiratory viruses in febrile children with leukemia. For this purpose, 138 febrile episodes in 51 children with leukemia were analyzed. Twelve types of respiratory viruses were searched for by viral culture, antigen detection, and polymerase chain reaction tests. RESULTS: Evidence of a respiratory viral infection was found in 61 of 138 febrile episodes (44%), accounting for an incidence of 0.8 (range, 0-2.4) per person year at risk during the treatment of leukemia. The most common viruses detected were rhinovirus (22%), respiratory syncytial virus (11%), human bocavirus (5%), and influenza A virus (4%). Dual viral infections were detected in 12 cases (9%). Half of the children had respiratory symptoms with cough being the most common symptom. Two children developed pneumonia. The mean duration of fever was 2.6 (SD 1.7) days in children with respiratory viral infection and 2.1 (SD 1.3) days in children without evidence of viral infection (P = 0.44). CONCLUSIONS: Respiratory viruses are found commonly during febrile episodes in children with leukemia. The detection of viruses permits the use of available antiviral agents, may explain a poor response to antimicrobial agents, and minimizes the proportion of febrile episodes without possible etiologic agents in children with leukemia.