[Air pollution and asthma in childhood].

Exposure to outdoor air pollutants and passive tobacco smoke are common but avoidable worldwide risk factors for morbidity and mortality of individuals. In addition to well-known effects of pollutants on the cardiovascular system and the development of cancer, in recent years the association between air pollution and respiratory morbidity has become increasingly apparent. Not only in adults, but also in children with asthma and in healthy children a clear harmful effect of exposure towards air pollutants has been demonstrated in many studies. Among others increased pollution has been shown to result in more frequent and more severe respiratory symptoms, more frequent exacerbations, higher need for asthma medication, poorer lung function and increased visits to the emergency department and more frequent hospitalisations. While these associations are well established, the available data on the role of air pollution in the development of asthma seems less clear. Some studies have shown that increased exposure towards tobacco smoke and air pollution leads to an increase in asthma incidence and prevalence; others were not able to confirm those findings. Possible reasons for this discrepancy are different definitions of the outcome asthma, different methods for exposure estimation and differences in the populations studied with differing underlying genetic backgrounds. Regardless of this inconsistency, several mechanisms have already been identified linking air pollution with asthma development. Among these are impaired lung growth and development, immunological changes, genetic or epigenetic effects or increased predisposition for allergic sensitisation. What the exact interactions are and which asthmatic phenotypes will be influenced most by pollutants will be shown by future studies. This knowledge will then be helpful in exploring possible preventive measures for the individual and to help policy makers in deciding upon most appropriate regulations on a population level.

SERIOUS MORBIDITY DUE TO ACUTE RESPIRATORY DISEASE ASSOCIATED WITH EPIDEMIC INFLUENZA

Current measures of the health impact of epidemic influenza are focused on analyses of death certificate data which may underestimate the true health effect. Previous investigations of influenza-related morbidity have either lacked virologic confirmation of influenza activity in the community or were not population-based. Community virologic surveillance in Houston has demonstrated that influenza viruses have produced epidemics each year since 1974. This study examined the relation of hospitalized for Acute Respiratory Disease (ARD) to the occurrence of influenza epidemics. Considering only Harris County residents, a total of 13,297 ARD hospital discharge records from hospitals representing 48.4% of Harris County hospital beds were compiled for the period July 1978 through June 1981. Variables collected from each discharge included: age, sex, race, dates of admission and discharge, length of stay, discharge disposition and a maximum of five diagnoses. This three year period included epidemics caused by Influenza A/Brazil (H1N1), Influenza B/Singapore, Influenza A/England (H1N1) and Influenza A/Bangkok (H3N2).^ Correlations of both ARD and pneumonia or influenza hospitalizations with indices of community morbidity (specifically, the weekly frequency of virologically-confirmed influenza virus infections) are consistently strong and suggest that hospitalization data reflect the pattern of influenza activity derived from virologic surveillance.^ While 65 percent of the epidemic period hospital deaths occurred in patients who were 65 years of age or older, fewer than 25 percent of epidemic period ARD hospitalizations occurred in persons of that age group. Over 97 percent of epidemic period hospital deaths were accompanied by a chronic underlying illness, however, 45 percent of ARD hospitalizations during epidemics had no mention of underlying illness. Over 2500 persons, approximately 35 percent of all persons hospitalized during the three epidemics, would have been excluded in an analysis for high risk candidates for influenza prophylaxis.^ These results suggest that examination of hospitalizations for ARD may better define the population-at-risk for serious morbidity associated with epidemic influenza. ^

Effects of Aerobic Training on Psychosocial Morbidity and Symptoms in Patients With Asthma A Randomized Clinical Trial

Background: Asthma symptoms reduce patients daily activities, impair their health-related quality of life (HRQoL), and increase their reports of anxiety and depress, all of which seem to be related to a decrease in asthma control. Aerobic exercise training is known to improve aerobic fitness and reduce dyspnea in asthmatics; however, its effect in reducing psychologic distress and symptoms remains poorly understood. We evaluated the role of an aerobic training program in improving HRQoL (primary aim) and reducing psychologic distress and asthma symptoms (secondary aims) for patients with moderate or severe persistent asthma. Methods: A total of 101 patients were randomly assigned to either a control group or an aerobic training group and studied during the period between medical consultations. Control group patients (educational program plus breathing exercises) (n = 51) and training group patients (educational program plus breathing exercises plus aerobic training) (n = 50) were followed twice a week during a 3-month period. HRQoL and levels of anxiety and depression were quantified before and after treatment. Asthma symptoms were evaluated monthly. Results: At 3 months, the domains (physical limitations, frequency of symptoms, and psychosocial) and total scores of HRQoL, significantly improved only in the training group patients (P < .001); the number of asthma-symptom-free days and anxiety and depression levels also significantly improved in this group (P < .001). In addition, a linear relationship between improvement in aerobic capacity and the days without asthma symptoms was observed (r = 0.47; P < .01). Conclusions: Our results suggest that aerobic training can play an important role in the clinical management of patients with persistent asthma. Further, they may be especially useful for patients with higher degrees of psychosocial distress.

Early neonatal morbidity and mortality in growth-discordant twins

Objective. To evaluate early neonatal morbidity and mortality in twin pregnancies with growth discordance. Design. Retrospective study. Setting. Tertiary teaching hospital, Sao Paulo, Brazil. Population. A total of 151 twin pregnancies managed and delivered at the Multiple Pregnancy Unit at Sao Paulo University Hospital between 1998 and 2004. Methods. Comparison between twin pregnancies with weight discordance 20% and pregnancies concordant for fetal weight. Cases with fetal death, abnormalities, twin-to-twin transfusion and delivery before 26 weeks or in another hospital were excluded. Outcome measures. Early neonatal morbidity (Apgar at 5 minutes 7, respiratory or neurological complications, infection, necrotizing enterocolitis, length of hospital stay) and mortality. Results. Forty (26.5%) pregnancies presented discordance 20% and 111 (73.5%) were concordant. In the discordant group, 75% of pregnancies had at least one growth restricted fetus (10th centile). In concordant twin pregnancies, monochorionic cases (22.5%) presented with lower gestational age (34.3 vs. 36.2 weeks), lower birthweight (2,067 vs. 2,334 g) and a longer period of hospital stay (5.5 vs. 3.0) compared to dichorionic concordant twins. No differences between monochorionic and dichorionic subgroups were observed in discordant twins. Pregnancies in which at least one baby was born with a birthweight below the 10th centile showed that discordant pregnancies had a lower gestational age at delivery (35.2 vs. 36.8 weeks) and a longer period of hospital stay (9 vs. 4 weeks) compared to concordant cases. Neonatal mortality was similar in discordant (3.7%) and concordant (4.5%) twins. Conclusion. Early perinatal morbidity is increased in twin pregnancies with birthweight discordance 20% only when associated with fetal growth restriction and low birthweight.

Molecular Characterization of Strains of Respiratory Syncytial Virus Identified in a Hematopoietic Stem Cell Transplant Outpatient Unit Over 2 Years: Community or Nosocomial Infection?

Respiratory syncytial virus (RSV) is recognized as the leading cause of nosocomial respiratory infection among hematopoietic stem cell transplant (HSCT) recipients, causing considerable morbidity and mortality. RSV is easily transmitted by contact with contaminated surfaces, and in HSCT units, more than 50% of RSV infections have been characterized as of nosocomial origin. From April 2001 to October 2002, RSV was identified by direct immunofluorescent assay in 42 symptomatic HSCT recipients. Seven RSV strains from 2001 and 12 RSV strains from 2002 were sequenced. RNA extraction, cDNA synthesis, and seminested polymerase chain reaction (PCR) with primers complementary to RSV genes G and F were pet-formed. PCR products were analyzed by nucleotide sequencing of the C-terminal region of gene G for typing (in group A or B). Of the 7 strains analyzed in 2001, only 2 belonged to group B; the other 5 belonged to group A. Of these 7 strains, 3 were identical and were from recipients receiving outpatient care. In 2002, of the 12 strains analyzed, 3 belonged to group A and the other 9 belonged to group B. Of these 9 strains, 7 were genetically identical and were also from recipients receiving outpatient care. Therefore, multiple strains of RSV cocirculated in the hematopoietic stem cell transplant units (ward and outpatient units) between 2001 and 2002. Nosocomial transmission was more likely to occur at the HSCT outpatient unit than in the HSCT ward. Infection control practices should also be implemented in the outpatient setting.

Lower respiratory tract infections among human immunodeficiency virus-exposed, uninfected infants

Objectives: To evaluate whether maternal HIV disease severity during pregnancy is associated with an increased likelihood of lower respiratory tract infections (LRTIs) in HIV-exposed, uninfected infants. Methods: HIV-exposed, uninfected, singleton, term infants enrolled in the NISDI Perinatal Study, with birth weight >2500 g were followed from birth until 6 months of age. LRTI diagnoses, hospitalizations, and associated factors were assessed. Results: Of 547 infants, 103 (18.8%) experienced 116 episodes of LRTI (incidence = 0.84 LRTIs/100 child-weeks). Most (81%) episodes were bronchiolitis. Forty-nine (9.0%) infants were hospitalized at least once with an LRTI. There were 53 hospitalizations (45.7%) for 116 LRTI episodes. None of these infants were breastfed. The odds of LRTI in infants whose mothers had CD4% <14 at enrollment were 4.4 times those of infants whose mothers had CD4% >= 29 (p = 0.003). The odds of LRTI in infants with a CD4+ count (cells/ mm(3)) <750 at hospital discharge were 16.0 times those of infants with CD4+ >= 750 (p = 0.002). Maternal CD4+ decline and infant hemoglobin at the 6-12 week visit were associated with infant LRTIs after 6-12 weeks and before 6 months of age. Conclusions: Acute bronchiolitis is common and frequently severe among HIV-exposed, uninfected infants aged 6 months or less. Lower maternal and infant CD4+ values were associated with a higher risk of infant LRTIs. Further understanding of the immunological mechanisms of severe LRTIs is needed. (C) 2010 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

The morbidity of Guillain-Barré syndrome admitted to the intensive care unit

Patients with severe forms of Guillain-Barré syndrome (GBS) require intensive care. Specific treatment, catheterization, and devices may increase morbidity in the intensive care unit (ICU). To understand the spectrum of morbidity associated with ICU care, the authors studied 114 patients with GBS. Major morbidity occurred in 60% of patients. Complications were uncommon if ICU stay was less than 3 weeks. Respiratory complications such as pneumonia and tracheobronchitis occurred in half of the patients and were linked to mechanical ventilation. Systemic infection occurred in one-fifth of patients and was more frequent with increasing duration of ICU admission. Direct complications of treatment and invasive procedures occurred infrequently. Life-threatening complications such as gastrointestinal bleeding and pulmonary embolism were very uncommon. Pulmonary morbidity predominates in patients with severe GBS admitted to the ICU. Attention to management of mechanical ventilation and weaning is important to minimize this complication of GBS. Other causes of morbidity in a tertiary center ICU are uncommon.

Child-care attendance and common morbidity: evidence of association in the literature and questions of design

Papers on child-care attendance as a risk factor for acute respiratory infections and diarrhea were reviewed. There was great variety among the studies with regard to the design, definition of exposure and definition of outcomes. All the traditional epidemiological study designs have been used. The studies varied in terms of how child-care attendance in general was defined, and for different settings. These definitions differed especially in relation to the minimum time of attendance required. The outcomes were also defined and measured in several different ways. The analyses performed were not always appropriate, leading to sets of results of uneven quality, and composed of different measures of association relating different exposures and outcomes, that made summarizing difficult. Despite that, the results reported were remarkably consistent. Only two of the papers reviewed failed to show some association between child-care attendance and increased acute respiratory infections, or diarrhea. On the other hand, the magnitude of the associations reported varied widely, especially for lower respiratory infections. Taken together, the studies so far published provide evidence that children attending child-care centers, especially those under three years of age, are at a higher risk of upper respiratory infections, lower respiratory infections, and diarrhea. The studies were not consistent, however, in relation to attendance at child-care homes. Children in such settings were sometimes similar to those in child-care centers, sometimes similar to those cared for at home, and sometimes presented an intermediate risk.

Assessing morbidity in the paediatric community

INTRODUCTION: Morbidity information is easily available from medical records but its scope is limited to the population attended by the health services. Information on the prevalence of diseases requires community surveys, which are not always feasible. These two sources of information represent two alternative assessments of disease occurrence, namely demand morbidity and perceived morbidity. The present study was conceived so as to elicit a potential relationship between them so that the former could be used in the absence of the latter. METHODS: A community of 13,365 families on the outskirts of S. Paulo, Brazil, was studied during the period from 15/Nov/1994 to 15/Jan/1995. Data regarding children less than 5 years old were collected from a household survey and from the 2 basic health units in the area. Prevalence of diseases was ascertained from perceived morbidity and compared to estimates computed from demand morbidity. RESULTS: Data analysis distinguished 2 age groups, infants less than 1 year old and children 1 to less than 5. The most important groups of diseases were respiratory diseases, diarrhoea, skin problems and infectious & parasitical diseases. Basic health units presented a better coverage for infants. Though disease frequencies were not different within or outside these units, a better coverage was found for diarrhoea and infectious & parasitical diseases in the infant group, and for diarrhoea in the older age group. Equivalence between the two types of morbidity was found to be limited to the infant group and concerned only the best covered diseases. The odds of a disease being seen at the health service should be of at least 4:10 to ensure this equivalence. CONCLUSION: It was concluded that, provided that health service coverage is good, demand morbidity can be taken as a reliable estimate of community morbidity.

Methodology in the epidemiological research of respiratory diseases and environmental pollution

There are complex and diverse methodological problems involved in the clinical and epidemiological study of respiratory diseases and their etiological factors. The association of urban growth, industrialization and environmental deterioration with respiratory diseases makes it necessary to pay more attention to this research area with a multidisciplinary approach. Appropriate study designs and statistical techniques to analyze and improve our understanding of the pathological events and their causes must be implemented to reduce the growing morbidity and mortality through better preventive actions and health programs. The objective of the article is to review the most common methodological problems in this research area and to present the most available statistical tools used.

Possible respiratory infection due to Aspergillus in workers from swineries and poultries

Recent epidemiologic studies clearly outline the link between fungal sensibilization and exarcebations of asthma, leading to increased morbidity and mortality. Amongst the filamentous fungi, Aspergillus scpecies have been strongly linked with exarcebations of asthma and other respiratory allergic diseases. Particles of approximately 1 to 4 pm are deposited in the lower respiratory tract. Therefore, conidia of A. fumigatus are small enough to traverse the terminal respiratory airways and reach the pulmonary alveoli, whereas the larger conidia of some other Aspergillus species, such as A. flavus and A. niger, tend to be deposited in the paranasal sinuses and upper airways. Exposute to environmental fungal spores has been associated with worsening asthma symptoms, lung function, hospital admissions and asthma-related deaths.

Clinical patterns and seasonal trends in respiratory syncytial virus hospitalizations in São Paulo, Brazil

The respiratory viruses are recognized as the most frequent lower respiratory tract pathogens for infants and young children in developed countries but less is known for developing populations. The authors conducted a prospective study to evaluate the occurrence, clinical patterns, and seasonal trends of viral infections among hospitalized children with lower respiratory tract disease (Group A). The presence of respiratory viruses in children's nasopharyngeal was assessed at admission in a pediatric ward. Cell cultures and immunofluorescence assays were used for viral identification. Complementary tests included blood and pleural cultures conducted for bacterial investigation. Clinical data and radiological exams were recorded at admission and throughout the hospitalization period. To better evaluate the results, a non- respiratory group of patients (Group B) was also constituted for comparison. Starting in February 1995, during a period of 18 months, 414 children were included- 239 in Group A and 175 in Group B. In Group A, 111 children (46.4%) had 114 viruses detected while only 5 children (2.9%) presented viruses in Group B. Respiratory Syncytial Virus was detected in 100 children from Group A (41.8%), Adenovirus in 11 (4.6%), Influenza A virus in 2 (0.8%), and Parainfluenza virus in one child (0.4%). In Group A, aerobic bacteria were found in 14 cases (5.8%). Respiratory Syncytial Virus was associated to other viruses and/or bacteria in six cases. There were two seasonal trends for Respiratory Syncytial Virus cases, which peaked in May and June. All children affected by the virus were younger than 3 years of age, mostly less than one year old. Episodic diffuse bronchial commitment and/or focal alveolar condensation were the clinical patterns more often associated to Respiratory Syncytial Virus cases. All children from Group A survived. In conclusion, it was observed that Respiratory Syncytial Virus was the most frequent pathogen found in hospitalized children admitted for severe respiratory diseases. Affected children were predominantly infants and boys presenting bronchiolitis and focal pneumonias. Similarly to what occurs in other subtropical regions, the virus outbreaks peak in the fall and their occurrence extends to the winter, which parallels an increase in hospital admissions due to respiratory diseases.

Tradução com adaptação cultural para portugês e determinação da reprodutibilidade do questionnaire on respiratory symptoms in preschool children

RESUMO: Introdução: A asma brônquica é uma entidade frequente em idade pediátrica, apresentando uma grande heterogeneidade clínica e significativa morbilidade quando não controlada. A identificação de crianças sintomáticas pode atrasar ou até mesmo diminuir a ocorrência de algumas alterações estruturais. Reconhece-se a necessidade de questionários sobre sintomas respiratórios em língua portuguesa, devidamente validados, que tenham como população-alvo os grupos etários inferiores a 3 anos. Deste modo, será possível não só um conhecimento mais rigoroso da asma e da sibilância infantil mas também a uniformização de metodologias para o desenvolvimento de estratégias a nível nacional. Objetivos: Tradução com adaptação cultural para português e determinação da reprodutibilidade do Questionnaire on respiratory symptoms in preschool children de Strippoli e colaboradores. Material e métodos: A escolha do questionário obedeceu a vários critérios, entre os quais o grupo etário, o tipo e número de perguntas. O Questionnaire on respiratory symptoms in preschool children de Strippoli e colaboradores é um questionário de autopreenchimento, dirigido a crianças entre os 12 e os 24 meses de idade e destinado a estudos epidemiológicos ao nível da comunidade. Aborda aspetos referentes a sintomas respiratórios (sibilância, tosse crónica, sintomas das vias aéreas superiores), cuidados médicos, terapêutica, características ambientais, história familiar e situação social. Procedemos à sua tradução, com especial atenção para a adaptação do ponto de vista cultural e linguístico, utilizando o método da tradução / retroversão, amplamente utilizado e descrito na literatura internacional. Seguidamente determinámos a reprodutibilidade da versão final em língua portuguesa – Questionário de sintomas respiratórios em idade pré-escolar – utilizando o teste-reteste. Para tal, incluíram-se crianças entre os 12 e os 36 meses de idade recrutadas num Centro de Saúde e em creches de Lisboa. A distribuição dos questionários decorreu em duas fases: na primeira fase foram entregues pessoalmente nos locais de recrutamento e na segunda fase foram enviados por correio para os domicílios das crianças, respeitando-se um intervalo mínimo de 2 semanas entre ambos. Resultados: Na primeira fase foram distribuídos 180 questionários, com uma taxa de reposta de 41% (n=74). Na segunda fase enviaram-se para os respetivos domicílios 70 questionários,obtendo-se uma taxa de resposta de 66% (n=46). Para a análise de reprodutibilidade foram incluídos apenas os questionários preenchidos em ambos os momentos pelo mesmo indivíduo (mãe, pai ou representante legal) (n=41). A idade média das crianças foi, na primeira fase, de 22,5 meses e, na segunda fase, de 23,7 meses, com um predomínio do sexo feminino (F:M =1:0,6). A mediana do tempo decorrido entre os dois momentos de preenchimento dos questionários foi de 26 dias. Obtivemos valores de concordância globalmente bons a muito bons, à semelhança do sucedido no trabalho original. Conclusões: Procedemos à tradução e avaliação da reprodutibilidade do Questionnaire on respiratory symptoms in preschool children. Pretende-se que venha a ser uma ferramenta útil para estudos epidemiológicos e programas de rastreio na comunidade, contribuindo deste modo para uma otimização da abordagem da asma / sibilância infantil a nível nacional. -------------ABSTRACT: Background: Asthma is a very common feature in childhood, with important clinical heterogeneity and morbidity if not properly controlled. Identifying symptomatic children may delay or even reduce several structural changes. The development of questionnaires on respiratory symptoms in Portuguese for children under 3 years old will allow not only a more accurate knowledge of infantile asthma and recurrent wheezing but also the standardization of methodologies to develop nationwide strategies. Objectives: The aim of this study was to translate and adapt to the Portuguese culture and to determine the repeatability of the Questionnaire on respiratory symptoms in preschool children by Strippoli et al. Material and methods: The choice of the questionnaire took in consideration several criteria, among which the target age, the type and the number of questions. The Questionnaire on respiratory symptoms in preschool children by Strippoli et al is a parent-completed questionnaire for assessment of respiratory symptoms in 1 to 2-year-old children, developed for cross-sectional and longitudinal studies. It contains sections on respiratory symptoms (wheezing, chronic cough and upper airways symptoms), healthcare utilization, treatment, environmental exposure, family history and social situation. For the process of translation we used the method of translation and back-translation, with particular concern to cultural and linguistic adaptation. To assess the repeatability of the final Portuguese version - Questionário de sintomas respiratórios em idade pré-escolar - we used the test–retest analyses. The questionnaires were distributed to parents of children between 12 and 36 months old attending nurseries and a Primary Care Center of Lisbon. The distribution took place in two phases: the first questionnaires were delivered in person (phase one) and an identical questionnaire was posted to the families that participated in the first phase, 2 weeks after the first one was returned (phase two). Results: The response rates were 41% (180/74) in the first phase and 66% (70/46) in the second phase. For test–retest analyses, we included the 41 children with the same respondent (mother, father or legal representative) in both occasions. The median age of the children was 22,5 months at the first phase and 23,7 months at the second phase, with a predominance of girls (F:M = 1:0,6). The median time between the fillings of both questionnaires was 26 days. Globally, agreement values were good to excellent, similarly to the original work. Conclusion: In the present study we translated the Questionnaire on respiratory symptoms in preschool children and assessed its repeatability. Overall, we expect it to be a valuable tool for epidemiological studies and community-based screening programs, thus contributing to improve the management of infantile asthma / recurrent wheezing nationwide.

The Intensive Care Global Study on Severe Acute Respiratory Infection (IC-GLOSSARI): a Multicenter, Multinational, 14-Day Inception Cohort Study

PURPOSE: In this prospective, multicenter, 14-day inception cohort study, we investigated the epidemiology, patterns of infections, and outcome in patients admitted to the intensive care unit (ICU) as a result of severe acute respiratory infections (SARIs). METHODS: All patients admitted to one of 206 participating ICUs during two study weeks, one in November 2013 and the other in January 2014, were screened. SARI was defined as possible, probable, or microbiologically confirmed respiratory tract infection with recent onset dyspnea and/or fever. The primary outcome parameter was in-hospital mortality within 60 days of admission to the ICU. RESULTS: Among the 5550 patients admitted during the study periods, 663 (11.9 %) had SARI. On admission to the ICU, Gram-positive and Gram-negative bacteria were found in 29.6 and 26.2 % of SARI patients but rarely atypical bacteria (1.0 %); viruses were present in 7.7 % of patients. Organ failure occurred in 74.7 % of patients in the ICU, mostly respiratory (53.8 %), cardiovascular (44.5 %), and renal (44.6 %). ICU and in-hospital mortality rates in patients with SARI were 20.2 and 27.2 %, respectively. In multivariable analysis, older age, greater severity scores at ICU admission, and hematologic malignancy or liver disease were independently associated with an increased risk of in-hospital death, whereas influenza vaccination prior to ICU admission and adequate antibiotic administration on ICU admission were associated with a lower risk. CONCLUSIONS: Admission to the ICU for SARI is common and associated with high morbidity and mortality rates. We identified several risk factors for in-hospital death that may be useful for risk stratification in these patients.

Viral etiology of acute respiratory infections among children in Porto Alegre, RS, Brazil

Although acute respiratory infections (ARIs) are a major cause of child morbidity and mortality in Southern Brazil, little information is available on their seasonality and viral etiology. This study was conducted on children under 5 years of age with ARI to assess viral etiology in the State of Rio Grande do Sul, from 1990 to 1992. A total of 862 nasopharyngeal secretion (NPS) samples were tested using indirect immunofluorescence. The results showed that 316 (36.6%) NPS samples were positive: 26.2% for RSV, 6% for adenovirus, 1.7% for influenzaviruses, 1.5% for parainfluenzaviruses, and 1.2% for mixed infection. The mean viral prevalence rates in out-patient services, emergency wards, and in-patient hospital wards were 26.7%, 53% and 42.3%, respectively. Respiratory syncytial virus (RSV) and adenovirus accounted for 91.4 % of the viral diagnoses. RSV was more frequent in children under one year of age at the three levels of health care and was prevalent in infants under six months. Adenovirus was the most prevalent pathogen in hospitalized children, in 1992. Influenza A virus showed an increased prevalence with age among out-patient children. This study shows the annual occurence of viral respiratory infections in the coldest months, with a significant annual variation in the frequency of RSV infection.