Acute and subchronic exposure to urban atmospheric pollutants aggravate acute respiratory failure in infants.

Urban air pollution is a major factor that affects the respiratory health of children and adolescents. Less studied is exposure during the first two years of life. This study analyzed the influence of acute and subchronic exposure to urban air pollutants on the severity of acute respiratory failure (ARF) in the first two years of life. This population-based study included 7364 infants hospitalized with ARF. Acute exposure was considered to have occurred 1, 3 and 7 days before hospitalization and subchronic exposure was considered the mean of the last 30 and 60 days. We found that for acute exposure, significant increases in days of hospitalization (LOS) occurred at lag 1 day for NO2 (0.24), SO2 (6.64), and CO (1.86); lag 3 days for PM10 (0.30), PM2.5 (0.37), SO2 (10.8), and CO (0.71); and lag 7 days for NO2 (0.16), SO2 (5.07) and CO (0.87). Increases in the risk of death occurred at lag 1 day for NO2 (1.06), SO2 (3.64), and CO (1.28); and lag 3 days for NO2 (1.04), SO2 (2.04), and CO (1.19). Subchronic exposures at 30 and 60 days occurred for SO2 (9.18, 3.77) and CO (6.53, 2.97), respectively. The associations were more pronounced with higher temperatures and lower relative humidity levels. We concluded that acute and subchronic exposure to higher atmospheric concentrations of all the pollutants studied were associated with greater severity of ARF. The greatest increases in LOS and risk of death occurred with hot and dry weather.

Blood leukocyte transcriptional modules and differentially expressed genes associated with disease severity and age in COVID-19 patients.

Since the molecular mechanisms determining COVID-19 severity are not yet well understood, there is a demand for biomarkers derived from comparative transcriptome analyses of mild and severe cases, combined with patients' clinico-demographic and laboratory data. Here the transcriptomic response of human leukocytes to SARS-CoV-2 infection was investigated by focusing on the differences between mild and severe cases and between age subgroups (younger and older adults). Three transcriptional modules correlated with these traits were functionally characterized, as well as 23 differentially expressed genes (DEGs) associated to disease severity. One module, correlated with severe cases and older patients, had an overrepresentation of genes involved in innate immune response and in neutrophil activation, whereas two other modules, correlated with disease severity and younger patients, harbored genes involved in the innate immune response to viral infections, and in the regulation of this response. This transcriptomic mechanism could be related to the better outcome observed in younger COVID-19 patients. The DEGs, all hyper-expressed in the group of severe cases, were mostly involved in neutrophil activation and in the p53 pathway, therefore related to inflammation and lymphopenia. These biomarkers may be useful for getting a better stratification of risk factors in COVID-19.

The importance of viral load in the severity of acute bronchiolitis in hospitalized infants.

OBJECTIVE: The relationship between viral load and the clinical evolution of bronchiolitis is controversial. Therefore, we aimed to analyze viral loads in infants hospitalized for bronchiolitis. METHODS: We tested for the presence of human respiratory syncytial virus (HRSV) or human rhinovirus (HRV) using quantitative molecular tests of nasopharyngeal secretions and recorded severity outcomes. RESULTS: We included 70 infants [49 (70%) HRSV, 9 (13%) HRV and 12 (17%) HRSV+HRV]. There were no differences among the groups according to the outcomes analyzed individually. Clinical scores showed greater severity in the isolated HRSV infection group. A higher isolated HRSV viral load was associated with more prolonged ventilatory support, oxygen therapy, and hospitalization days, even after adjustment for the age and period of nasopharyngeal secretion collection. In the co-infection groups, there was a longer duration of oxygen therapy when the HRSV viral load was predominant. Isolated HRV infection and co-infection with a predominance of HRV were not associated with severity. CONCLUSION: Higher HRSV viral load in isolated infections and the predominance of HRSV in co-infections, independent of viral load, were associated with greater severity. These results contribute to the development of therapeutic and prophylactic approaches and a greater understanding of the pathophysiology of bronchiolitis.

The importance of viral load in the severity of acute bronchiolitis in hospitalized infants

OBJECTIVE: The relationship between viral load and the clinical evolution of bronchiolitis is controversial. Therefore, we aimed to analyze viral loads in infants hospitalized for bronchiolitis. METHODS: We tested for the presence of human respiratory syncytial virus (HRSV) or human rhinovirus (HRV) using quantitative molecular tests of nasopharyngeal secretions and recorded severity outcomes. RESULTS: We included 70 infants [49 (70%) HRSV, 9 (13%) HRV and 12 (17%) HRSV+HRV]. There were no differences among the groups according to the outcomes analyzed individually. Clinical scores showed greater severity in the isolated HRSV infection group. A higher isolated HRSV viral load was associated with more prolonged ventilatory support, oxygen therapy, and hospitalization days, even after adjustment for the age and period of nasopharyngeal secretion collection. In the co-infection groups, there was a longer duration of oxygen therapy when the HRSV viral load was predominant. Isolated HRV infection and co-infection with a predominance of HRV were not associated with severity. CONCLUSION: Higher HRSV viral load in isolated infections and the predominance of HRSV in co-infections, independent of viral load, were associated with greater severity. These results contribute to the development of therapeutic and prophylactic approaches and a greater understanding of the pathophysiology of bronchiolitis.

Distinct transcriptional modules in the peripheral blood mononuclear cells response to human respiratory syncytial virus or to human rhinovirus in hospitalized infants with bronchiolitis.

Human respiratory syncytial virus (HRSV) is the main cause of bronchiolitis during the first year of life, when infections by other viruses, such as rhinovirus, also occur and are clinically indistinguishable from those caused by HRSV. In hospitalized infants with bronchiolitis, the analysis of gene expression profiles from peripheral blood mononuclear cells (PBMC) may be useful for the rapid identification of etiological factors, as well as for developing diagnostic tests, and elucidating pathogenic mechanisms triggered by different viral agents. In this study we conducted a comparative global gene expression analysis of PBMC obtained from two groups of infants with acute viral bronchiolitis who were infected by HRSV (HRSV group) or by HRV (HRV group). We employed a weighted gene co-expression network analysis (WGCNA) which allows the identification of transcriptional modules and their correlations with HRSV or HRV groups. This approach permitted the identification of distinct transcription modules for the HRSV and HRV groups. According to these data, the immune response to HRSV infection-comparatively to HRV infection-was more associated to the activation of the interferon gamma signaling pathways and less related to neutrophil activation mechanisms. Moreover, we also identified host-response molecular markers that could be used for etiopathogenic diagnosis. These results may contribute to the development of new tests for respiratory virus identification. The finding that distinct transcriptional profiles are associated to specific host responses to HRSV or to HRV may also contribute to the elucidation of the pathogenic mechanisms triggered by different respiratory viruses, paving the way for new therapeutic strategies.

Infections Caused by HRSV A ON1 Are Predominant among Hospitalized Infants with Bronchiolitis in São Paulo City.

Human respiratory syncytial virus is the main cause of respiratory infections in infants. Several HRSV genotypes have been described. Goals. To describe the main genotypes that caused infections in São Paulo (2013-2015) and to analyze their clinical/epidemiological features. Methods. 94 infants (0-6 months) with bronchiolitis were studied. Clinical/epidemiological information was collected; a search for 16 viruses in nasopharyngeal secretion (PCR-real-time and conventional, sequencing, and phylogenetic analyses) was performed. Results. The mean age was 2.4 m; 48% were male. The mean length of hospital stay was 4.4 d (14% in the Intensive Care Unit). The positive rate of respiratory virus was 98.9%; 73 cases (77.6%) were HRSV (76,7% HRSVA). HRSVA formed three clusters: ON1 (n = 34), NA1 (n = 1), and NA2 (n = 4). All HRSVB were found to cluster in the BA genotype (BA9-n = 10; BA10-n = 3). Clinical analyses showed no significant differences between the genotype AON1 and other genotypes. Conclusion. This study showed a high rate of HRSV detection in bronchiolitis. HRSVA ON1, which has recently been described in other countries and has not been identified in previous studies in the southeast region of Brazil, was predominant. The clinical characteristics of the infants that were infected with AON1 were similar to infants with infections by other genotypes.

Associations of maternal personal exposure to air pollution on fetal weight and fetoplacental Doppler: A prospective cohort study.

We determined the influence of maternal air pollution exposure during each trimester of pregnancy on fetal and birth weight and fetoplacental hemodynamics. In total, 366 women with singleton pregnancies were prospectively followed in the city of São Paulo, Brazil. Nitrogen dioxide (NO2) and ozone (O3) were measured during each trimester using passive personal samplers. We evaluated fetal weight and Doppler velocimetry data from the umbilical, middle cerebral, and uterine arteries in the 3rd trimester, and birth weight. Multivariate analysis was performed, controlling for known determinants of fetal weight. Exposure to higher levels of O3 during the 2nd trimester was associated with higher umbilical artery pulsatility indices (PIs) [p=0.013; beta=0.017: standard error (SE)=0.007]. Exposure to higher levels of O3 during the 3rd trimester was associated with lower umbilical artery PIs (p=0.011; beta=-0.021; SE=0.008). Our results suggest that in the environment of São Paulo, O3 may affects placental vascular resistance.

The health burden of pollution: the impact of prenatal exposure to air pollutants.

Exposure to atmospheric pollutants in both open and closed environments is a major cause of morbidity and mortality that may be both controlled and minimized. Despite growing evidence, several controversies and disagreements exist among the studies that have analyzed the effects of prenatal pollutant exposure. This review article aims to analyze primary scientific evidence of the effects of air pollution during pregnancy and the impact of these effects on the fetus, infant health, and in particular, the respiratory system. We performed a review of articles from the PubMed and Web of Science databases that were published in English within the past 5 years, particularly those related to birth cohorts that began in pregnancy with follow-up until the first years of life. The largest reported effects are associated with prenatal exposure to particulate matter, nitrogen dioxide, and tobacco smoke. The primary effects affect birth weight and other parameters of fetal biometry. There is strong evidence regarding the impact of pollutants on morbidity secondary to respiratory problems. Growing evidence links maternal smoking to childhood asthma and wheezing. The role of passive maternal smoking is less clear. Great heterogeneity exists among studies. There is a need for additional studies on birth cohorts to monitor the relationship between the exposure of pregnant women to pollutants and their children's progress during the first years of life.

Quality of life of adolescents with type 1 diabetes.

INTRODUCTION: Diabetes mellitus is a highly prevalent chronic disease. Type 1 diabetes mellitus usually develops during infancy and adolescence and may affect the quality of life of adolescents. OBJECTIVE: To evaluate the quality of life of adolescents with type 1 diabetes mellitus in a metropolitan region of western central Brazil. METHODS: Adolescents aged 10-19 years who had been diagnosed with type 1 diabetes mellitus at least 1 year previously were included. Patients with verbal communication difficulties, severe disease, and symptomatic hypo- or hyperglycemic crisis as well as those without an adult companion and who were <18 years of age were excluded. The self-administered Diabetes Quality of Life for Youths instrument was applied. RESULTS: Among 96 adolescents (57% females; 47% white, and 53% nonwhite), 81% had an HbA1c level of >7%. In general, the adolescents consistently reported having a good quality of life. The median scores for the domains of the instrument were as follows: "satisfaction": 35; "impact": 51; and "worries": 26. The total score for all domains was 112. Bivariate analysis showed significant associations among a lower family income, public health assistance, and insulin type in the "satisfaction" domain; and a lower family income, public health assistance, public school attendance, and a low parental education level in the "worries" domain and for the total score. A longer time since diagnosis was associated with a worse total score. Multivariable analysis confirmed the association of a worse quality of life with public health assistance, time since diagnosis, and sedentary lifestyle in the "satisfaction" domain; female gender in the "worries" domain; and public health assistance for the total score. CONCLUSIONS: Overall, the adolescents evaluated in this study viewed their quality of life as good. Specific factors that led to the deterioration of quality of life, including public assistance, time since diagnosis, sedentary lifestyle, and female gender, were identified. No potential conflict of interest was reported.

Quality of life of adolescents with type 1 diabetes

INTRODUCTION: Diabetes mellitus is a highly prevalent chronic disease. Type 1 diabetes mellitus usually develops during infancy and adolescence and may affect the quality of life of adolescents. OBJECTIVE: To evaluate the quality of life of adolescents with type 1 diabetes mellitus in a metropolitan region of western central Brazil. METHODS: Adolescents aged 10-19 years who had been diagnosed with type 1 diabetes mellitus at least 1 year previously were included. Patients with verbal communication difficulties, severe disease, and symptomatic hypo- or hyperglycemic crisis as well as those without an adult companion and who were <18 years of age were excluded. The self-administered Diabetes Quality of Life for Youths instrument was applied. RESULTS: Among 96 adolescents (57% females; 47% white, and 53% nonwhite), 81% had an HbA1c level of >7%. In general, the adolescents consistently reported having a good quality of life. The median scores for the domains of the instrument were as follows: “satisfaction”: 35; “impact”: 51; and “worries“: 26. The total score for all domains was 112. Bivariate analysis showed significant associations among a lower family income, public health assistance, and insulin type in the “satisfaction” domain; and a lower family income, public health assistance, public school attendance, and a low parental education level in the “worries“ domain and for the total score. A longer time since diagnosis was associated with a lower total score. Multivariable analysis confirmed the association of a worse quality of life with public health assistance, time since diagnosis, and sedentary lifestyle in the “satisfaction” domain; female gender in the “worries” domain; and public health assistance for the total score. CONCLUSIONS: Overall, the adolescents evaluated in this study viewed their quality of life as good. Specific factors that ...

Infecções por vírus respiratórios em lactentes com suspeita clínica de coqueluche / Respiratory viral infections in infants with clinically suspected pertussis

OBJETIVO: avaliar a frequência das infecções por vírus respiratórios em lactentes hospitalizados com suspeita clínica de coqueluche e analisar suas características admissionais e evolutivas. MÉODOS: foi realizado um estudo de coorte histórica, em um serviço sentinela para coqueluche, no qual a pesquisa de vírus respiratórios também foi rotineira para os lactentes hospitalizados com problemas respiratórios. Foram incluídos todos os lactentes submetidos à notificação compulsória de suspeita de coqueluche. Foram realizadas pesquisas para Bordetela pertussis - BP (PCR/cultura) e vírus respiratórios - VR (imunofluorescência). Foram excluídos os pacientes que haviam recebido macrolídeos previamente à internação. Os dados clínicos foram obtidos dos prontuários. RESULTADOS: dentre os 67 pacientes analisados, a pesquisa para BP foi positiva em 44% e para VR em 26%. Não houve identificação etiológica em 35% e em 5% houve codetecção de VR e BP. Todos os pacientes apresentaram características demográficas semelhantes. A presença de tosse seguida de guincho inspiratório ou cianose foi um forte preditor de coqueluche, assim como, leucocitose e linfocitose evidentes. Coriza e dispneia foram mais frequentes nas infecções virais. Houve suspensão do uso de macrolídeos em 40% dos pacientes com pesquisa positiva para VR e negativa para BP. CONCLUSÃO: os resultados sugerem que lactentes hospitalizados com suspeita de coqueluche podem apresentar infecção viral e a pesquisa etiológica pode possibilitar a redução do uso de macrolídeos em alguns casos. No entanto, salienta-se que o diagnóstico etiológico de infecção por vírus respiratórios, por si só, não exclui a possibilidade de infecção por Bordetella pertussis.

OBJECTIVE: to evaluate the frequency of respiratory viral infections in hospitalized infants with clinical suspicion of pertussis, and to analyze their characteristics at hospital admission and clinical outcomes. METHODS: a historical cohort study was performed in a reference service for pertussis, in which the research of respiratory viruses was also a routine for infants hospitalized with respiratory problems. All infants reported as suspected cases of pertussis were included. Tests for Bordetella pertussis (BP) (polymerase chain reaction/culture) and for respiratory viruses (RVs) (immunofluorescence) were performed. Patients who received macrolides before hospitalization were excluded. Clinical data were obtained from medical records. RESULTS: among the 67 patients studied, BP tests were positive in 44%, and 26% were positive for RV. There was no etiological identification in 35%, and RV combined with BP was identified in 5%. All patients had similar demographic characteristics. Cough followed by inspiratory stridor or cyanosis was a strong predictor of pertussis, as well as prominent leukocytosis and lymphocytosis. Rhinorrhea and dyspnea were more frequent in viral infections. Macrolides were discontinued in 40% of patients who tested positive for RV and negative for BP. CONCLUSION: the results suggest that viral infection can be present in hospitalized infants with clinical suspicion of pertussis, and etiological tests may enable a reduction in the use of macrolides in some cases. However, the etiological diagnosis of respiratory virus infection, by itself, does not exclude the possibility of infection with BP.

Respiratory viral infections in infants with clinically suspected pertussis.

OBJECTIVE: to evaluate the frequency of respiratory viral infections in hospitalized infants with clinical suspicion of pertussis, and to analyze their characteristics at hospital admission and clinical outcomes. METHODS: a historical cohort study was performed in a reference service for pertussis, in which the research of respiratory viruses was also a routine for infants hospitalized with respiratory problems. All infants reported as suspected cases of pertussis were included. Tests for Bordetella pertussis (BP) (polymerase chain reaction/culture) and for respiratory viruses (RVs) (immunofluorescence) were performed. Patients who received macrolides before hospitalization were excluded. Clinical data were obtained from medical records. RESULTS: Among the 67 patients studied, BP tests were positive in 44%, and 26% were positive for RV. There was no etiological identification in 35%, and RV combined with BP was identified in 5%. All patients had similar demographic characteristics. Cough followed by inspiratory stridor or cyanosis was a strong predictor of pertussis, as well as prominent leukocytosis and lymphocytosis. Rhinorrhea and dyspnea were more frequent in viral infections. Macrolides were discontinued in 40% of patients who tested positive for RV and negative for BP. CONCLUSION: the results suggest that viral infection can be present in hospitalized infants with clinical suspicion of pertussis, and etiological tests may enable a reduction in the use of macrolides in some cases. However, the etiological diagnosis of respiratory virus infection, by itself, does not exclude the possibility of infection with BP.

Congenital hypothyroidism: recommendations of the Thyroid Department of the Brazilian Society of Endocrinology and Metabolism.

Congenital hypothyroidism (CH) is the most common congenital endocrine disorder, with an incidence of 1:2,000 to 1:4,000 live births and it is a leading preventable mental retardation. Neonatal Screening Programs allow early identification of the disease and the adequate treatment of affected children can avoid the complications related to deprivation of the hormone. Most cases of primary congenital hypothyroidism (85%) are due to thyroid dysgenesis (ectopia, hypoplasia or agenesis) while the remaining result from defects in hormone synthesis. Affected children (> 95%) usually have no symptoms suggesting the disease at birth. The most frequent symptoms and signs are prolonged neonatal jaundice, hoarse cry, lethargy, slow movements, constipation, macroglossia, umbilical hernia, large fontanelle, hypotonia and dry skin. Around the world, various strategies are used for the screening of the CH. In Brazil, screening for CH is mandatory by law and usually done by serum TSH in dried blood collected from the heel. The recommended age for performing this test is after 48 hours of life until the 4th day. Diagnostic confirmation is required dosing TSH and free T4 or total T4 in serum.

Hipotireoidismo congênito: recomendações do Departamento de Tireoide da Sociedade Brasileira de Endocrinologia e Metabologia / Congenital hypothyroidism: recommendations of the Thyroid Department of the Brazilian Society of Endocrinology and Metabolism

O hipotireoidismo congênito (HC) é o distúrbio endócrino congênito mais frequente, com incidência variando de 1:2.000 a 1:4.000 crianças nascidas vivas e uma das principais causas de retardo mental que pode ser prevenida. Os Programas de Triagem Neonatal para a doença permitem a identificação precoce dos afetados e seu tratamento de modo a evitar as complicações da falta do hormônio. A maioria dos casos de hipotireoidismo congênito é decorrente de disgenesias tireoidianas (85%), entre elas a ectopia, hipoplasia ou agenesia tireoidianas, e os demais resultam de defeitos de síntese hormonal. As crianças afetadas (> 95%) geralmente não apresentam sintomas sugestivos da doença ao nascimento. Os sintomas e sinais mais comuns são: icterícia neonatal prolongada, choro rouco, letargia, movimentos lentos, constipação, macroglossia, hérnia umbilical, fontanelas amplas, hipotonia e pele seca. Várias estratégias são utilizadas para a triagem do HC. No Brasil, esta é obrigatória por lei e geralmente é feita com a dosagem de TSH em sangue seco coletado do calcanhar. A idade recomendada para sua realização é após as 48 horas de vida até o quarto dia. A confirmação diagnóstica é obrigatória com as dosagens de TSH e T4 livre ou T4 total.

Congenital hypothyroidism (CH) is the most common congenital endocrine disorder, with an incidence of 1:2,000 to 1:4,000 live births and it is a leading preventable mental retardation. Neonatal Screening Programs allow early identification of the disease and the adequate treatment of affected children can avoid the complications related to deprivation of the hormone. Most cases of primary congenital hypothyroidism (85%) are due to thyroid dysgenesis (ectopia, hypoplasia or agenesis) while the remaining result from defects in hormone synthesis. Affected children (> 95%) usually have no symptoms suggesting the disease at birth. The most frequent symptoms and signs are prolonged neonatal jaundice, hoarse cry, lethargy, slow movements, constipation, macroglossia, umbilical hernia, large fontanelle, hypotonia and dry skin. Around the world, various strategies are used for the screening of the CH. In Brazil, screening for CH is mandatory by law and usually done by serum TSH in dried blood collected from the heel. The recommended age for performing this test is after 48 hours of life until the 4th day. Diagnostic confirmation is required dosing TSH and free T4 or total T4 in serum.

Etiological diagnosis reduces the use of antibiotics in infants with bronchiolitis.

OBJECTIVE: Acute bronchiolitis is a leading cause of infant hospitalization and is most commonly caused by respiratory syncytial virus. Etiological tests are not required for its diagnosis, but the influence of viral screening on the therapeutic approach for acute bronchiolitis remains unclear. METHODS: A historical cohort was performed to assess the impact of viral screening on drug prescriptions. The study included infants up to one year of age who were hospitalized for bronchiolitis. Virus screening was performed using immunofluorescence assays in nasopharyngeal aspirates. The clinical data were obtained from the patients' medical records. Therapeutic changes were considered to be associated with viral screening when made within 24 hours of the release of the results. RESULTS: The frequency of prescriptions for beta agonists, corticosteroids and antibiotics was high at the time of admission and was similar among the 230 patients. The diagnosis of pneumonia and otitis was associated with the introduction of antibiotics but did not influence antibiotics maintenance after the results of the virus screening were obtained. Changes in the prescriptions were more frequent for the respiratory syncytial virus patients compared to patients who had negative viral screening results (p =0.004), especially the discontinuation of antibiotics (p<0.001). The identification of respiratory syncytial virus was associated with the suspension of antibiotics (p= 0.003), even after adjusting for confounding variables (p = 0.004); however, it did not influence the suspension of beta-agonists or corticosteroids. CONCLUSION: The identification of respiratory syncytial virus in infants with bronchiolitis was independently associated with the discontinuation of antibiotics during hospitalization.

Etiological diagnosis reduces the use of antibiotics in infants with bronchiolitis

OBJECTIVE: Acute bronchiolitis is a leading cause of infant hospitalization and is most commonly caused by respiratory syncytial virus. Etiological tests are not required for its diagnosis, but the influence of viral screening on the therapeutic approach for acute bronchiolitis remains unclear. METHODS: A historical cohort was performed to assess the impact of viral screening on drug prescriptions. The study included infants up to one year of age who were hospitalized for bronchiolitis. Virus screening was performed using immunofluorescence assays in nasopharyngeal aspirates. The clinical data were obtained from the patients' medical records. Therapeutic changes were considered to be associated with viral screening when made within 24 hours of the release of the results. RESULTS: The frequency of prescriptions for beta agonists, corticosteroids and antibiotics was high at the time of admission and was similar among the 230 patients. The diagnosis of pneumonia and otitis was associated with the introduction of antibiotics but did not influence antibiotics maintenance after the results of the virus screening were obtained. Changes in the prescriptions were more frequent for the respiratory syncytial virus patients compared to patients who had negative viral screening results (p =0.004), especially the discontinuation of antibiotics (p<0.001). The identification of respiratory syncytial virus was associated with the suspension of antibiotics (p= 0.003), even after adjusting for confounding variables (p = 0.004); however, it did not influence the suspension of beta-agonists or corticosteroids. CONCLUSION: The identification of respiratory syncytial virus in infants with bronchiolitis was independently associated with the discontinuation of antibiotics during hospitalization.

Epidemiology and genetic variability of human metapneumovirus during a 4-year-long study in Southeastern Brazil.

Epidemiological and molecular characteristics of human metapneumovirus (hMPV) were compared with human respiratory syncytial virus (hRSV) in infants and young children admitted for acute lower respiratory tract infections in a prospective study during four consecutive years in subtropical Brazil. GeneScan polymerase chain assays (GeneScan RT-PCR) were used to detect hMPV and hRSV in nasopharyngeal aspirates of 1,670 children during January 2003 to December 2006. hMPV and hRSV were detected, respectively, in 191 (11.4%) and in 702 (42%) of the children admitted with acute lower respiratory tract infections at the Sao Paulo University Hospital. Sequencing data of the hMPV F gene revealed that two groups of the virus, each divided into two subgroups, co-circulated during three consecutive years. It was also shown that a clear dominance of genotype B1 occurred during the years 2004 and 2005, followed by genotype A2 during 2006.