Neurological Impact of Respiratory Viruses: Insights into Glial Cell Responses in the Central Nervous System.

Respiratory viral infections pose a significant public health threat, particularly in children and older adults, with high mortality rates. Some of these pathogens are the human respiratory syncytial virus (hRSV), severe acute respiratory coronavirus-2 (SARS-CoV-2), influenza viruses (IV), human parvovirus B19 (B19V), and human bocavirus 1 (HBoV1). These viruses cause various respiratory symptoms, including cough, fever, bronchiolitis, and pneumonia. Notably, these viruses can also impact the central nervous system (CNS), leading to acute manifestations such as seizures, encephalopathies, encephalitis, neurological sequelae, and long-term complications. The precise mechanisms by which these viruses affect the CNS are not fully understood. Glial cells, specifically microglia and astrocytes within the CNS, play pivotal roles in maintaining brain homeostasis and regulating immune responses. Exploring how these cells interact with viral pathogens, such as hRSV, SARS-CoV-2, IVs, B19V, and HBoV1, offers crucial insights into the significant impact of respiratory viruses on the CNS. This review article examines hRSV, SARS-CoV-2, IV, B19V, and HBoV1 interactions with microglia and astrocytes, shedding light on potential neurological consequences.

Efficacy and safety of withholding antimicrobial therapy in children with cancer, fever, and neutropenia, with a demonstrated viral respiratory infection: a randomized clinical trial.

OBJECTIVES: To validate the efficacy and safety of withholding antimicrobial therapy in a new cohort of children with cancer and febrile neutropenia (FN) having a demonstrated viral respiratory tract infection. METHODS: Prospective, multicenter, noninferiority, randomized study, approved by the ethical committee, in children presenting with FN at seven hospitals in Chile, evaluated at admission for diagnosis of bacterial and viral pathogens. Children who were positive for a respiratory virus, negative for a bacterial pathogen, and had a favourable evolution after 48-72 hours of antimicrobial therapy were randomized to either maintain or withhold antimicrobial therapy. The primary endpoint was the percentage of episodes with an uneventful resolution, whereas the secondary endpoints were days of fever, days of hospitalization, requirement of antimicrobial treatment readministration, sepsis, paediatric intensive care unit admission, and death. RESULTS: A total of 301 of 939 children with FN episodes recruited between March 2021 and December 2023 had a respiratory virus as a unique identified microorganism, of which 139 had a favourable evolution at 48-72 hours and were randomized, 70 to maintain and 69 to withdraw antimicrobial therapy. The median days of antimicrobial therapy was 5 (IQR 3-6) versus 3 (IQR 3-6) days (p < 0.001), with similar frequency of uneventful resolution 66/70 (94%) and 66/69 (96%); relative risk, 1.01; (95% CI, 0.93 to 1.09), absolute risk difference 0.01; (95% CI, -0.05 to 0.08) and similar number of days of fever and days of hospitalization. No cases of sepsis, paediatric intensive care unit admission, or death were reported. DISCUSSION: We validated the strategy of withdrawal antimicrobial therapy in children with FN and viral respiratory tract infection based on clinical and microbiological/molecular diagnostic criteria. This will enable advances in antimicrobial stewardship strategies with a possible future impact on antimicrobial resistance.

Overnutrition as a risk factor for more serious respiratory viral infections in children: A retrospective study in hospitalized patients.

BACKGROUND: The prevalence of obesity has increased dramatically in children worldwide. Obesity has been recognized as a risk factor for more serious viral respiratory infections, mainly in adults. OBJECTIVE: To study the relationship between overnutrition (obesity and overweight) and clinical severity in children hospitalized with acute respiratory infections of viral origin. METHODS: One hundred and forty-three clinical records of children between 2 and 18 years old hospitalized for acute respiratory infection at Clínica Dávila (2014-2018) were analyzed, recording the respiratory viruses detected at the time of hospitalization, weight, and height. Nutritional status was estimated using Z score or body mass index, according to age. RESULTS: Eighty-tree3 children (58%) were positive for more than one respiratory virus. The main virus detected in monoinfection was adenovirus (9.8%), followed by respiratory syncytial virus (7.7%) and parainfluenza virus (7.7%). There were no deaths. Patients with obesity presented more days of hospitalization (P = .04), oxygen therapy (P = .03) and mechanical ventilation (P < .001), as well as a higher probability of requiring mechanical ventilation (P = .001) and of ICU admission (P = .003) compared with children with normal weight. Patients with overweight presented more days of mechanical ventilation (P < .001) than patients with normal weight. No significant differences were found between the presence of viral coinfection and nutritional status. CONCLUSION: Overnutrition is associated with greater severity of viral respiratory infection in hospitalized children.

Respiratory virus infections in hospitalized and non-hospitalized children: determinants of severe course of the disease.

INTRODUCTION: Viral respiratory disease constitutes a great burden worldwide mainly among children. OBJECTIVE: One pursued to compare disease characteristics of children who required hospitalization from those who did not require hospitalization due to a viral respiratory disease. METHODOLOGY: Medical and demographic data were collected through questionnaires and nasopharyngeal aspirates were tested for detection of respiratory disease viruses of in and outpatients up to five years old, presenting acute respiratory infection. RESULTS: Respiratory syncytial virus predominated among hospitalized children while other viruses (Human rhinovirus, Influenza virus, Parainfluenza virus, Adenovirus, and Human metapneumovirus) together predominated among non-hospitalized patients. Although children with underlying risk condition required longer hospitalization, previously healthy children presented severe disease and required hospitalization as well. Also, clinical characteristics were not found that may distinguish RSV infected children who had comorbidities from those previously healthy. CONCLUSIONS: Children who were hospitalized due to respiratory distress had well defined characteristics: early age, respiratory syncytial virus infection, bronchiolitis and presence of comorbidity. Nevertheless, rapid respiratory syncytial virus identification among early age children may be of great value in order to avoid medical misconduct, such as unnecessary antibiotic prescription and preventive health care before an eventual clinical worsening encompassing previous health status.

Prior upregulation of interferon pathways in the nasopharynx impacts viral shedding following live attenuated influenza vaccine challenge in children.

In children lacking influenza-specific adaptive immunity, upper respiratory tract innate immune responses may influence viral replication and disease outcome. We use trivalent live attenuated influenza vaccine (LAIV) as a surrogate challenge model in children aged 24-59 months to identify pre-infection mucosal transcriptomic signatures associated with subsequent viral shedding. Upregulation of interferon signaling pathways prior to LAIV is significantly associated with lower strain-specific viral loads (VLs) at days 2 and 7. Several interferon-stimulated genes are differentially expressed in children with pre-LAIV asymptomatic respiratory viral infections and negatively correlated with LAIV VLs. Upregulation of genes enriched in macrophages, neutrophils, and eosinophils is associated with lower VLs and found more commonly in children with asymptomatic viral infections. Variability in pre-infection mucosal interferon gene expression in children may impact the course of subsequent influenza infections. This variability may be due to frequent respiratory viral infections, demonstrating the potential importance of mucosal virus-virus interactions in children.

Infecciones respiratorias virales en episodios de fiebre en niños con trasplante de precursores hematopoyéticos / Respiratory viral infections during episodes of fever in children undergoing hematopoietic stem cell transplantation

Resumen Introducción: Los niños que reciben trasplante de precursores hematopoyéticos (TPH) pueden presentar infecciones respiratorias virales (IRV) durante episodios febriles. Los datos sobre su evolución clínica son escasos, así como la comparación de ellos con infecciones bacterianas (IB). Objetivo: Caracterizar la evolución clínica de pacientes con IRV, en comparación con IB en niños con TPH, cursando un episodio febril. Método: Estudio prospectivo en pacientes ≤ 18 años con cáncer y TPH ingresados por fiebre en el Hospital Luis Calvo Mackenna (2016-2019). Se realizó evaluación clínica y de laboratorio: hemocultivos, RPC para patógenos respiratorios (Filmarray®), cuantificación viral y medición de citoquinas en muestra nasal (Luminex®, 38 citoquinas). Se compararon los grupos IRV, IB y los de etiología no precisada (ENP) en relación con: infección respiratoria aguda (IRA), citoquinas nasales, ingreso a UCI, necesidad de ventilación mecánica, mortalidad y suspensión de antimicrobianos. Resultados: De 56 episodios febriles, 35 fueron IRV, 12 IB y 9 de ENP. Mediana de edad fue 8,5 años, 62% masculino. Un 94% de los casos IRV presentó IRA sintomática, versus 33% en los grupos IB y ENP (p < 0,001), con IRA baja en 69% de las IRV (p < 0,001). Rinovirus (54%) y coronavirus (15%) fueron las etiologías más frecuentemente detectadas. No hubo diferencias en citoquinas nasales entre los grupos IRV e IB. Ingreso a UCI: 11% del grupo IRV, 17% de IB y 11% de ENP (p = 0,88). Requirieron ventilación mecánica sólo 2 pacientes (p = 0,37) sin fallecimiento. Tras la detección viral respiratoria por RPC, se suspendió antimicrobianos en 26% de los casos con IRV (p = 0,04). Conclusión: Las IRV son frecuentes en niños con TPH y episodios febriles. La detección viral podría optimizar y racionalizar el uso de antimicrobianos en esta población.

Abstract Background: Children undergoing hematopoietic stem cell transplant (HSCT) can develop respiratory viral infections (RVI) during fever episodes. There are few data about clinical outcomes in RVI and compared to bacterial infections (BI) in this population. Aim: To determine clinical outcome of RVI, compared to BI in children with HSCT. Methods: Prospective study, patients ≤ 18 years with cancer and HSCT admitted with fever at a National Bone Marrow Transplant Center (Hospital Calvo Mackenna), Chile, (April-2016 to May-2019). Clinical assessment, laboratory tests, blood cultures, nasopharyngeal sample for multiplex-PCR (Filmarray®), viral loads by PCR and cytokine panel (Luminex®, 38 cytokines) were performed. The following outcomes were evaluated: upper/lower respiratory tract disease (RTD), admission to ICU, mechanical ventilation, mortality and antimicrobial withdrawal. Results: Of 56 febrile episodes, 35 (63%) were RVI, 12 (21%) BI and 9 (16%) with unknown etiology (UE). Median of age was 8.5 years, 62% male gender. Rhinovirus (54%) and coronavirus (15%) were the more frequent detected viruses. No significant differences in cytokine levels were observed between RVI and BI. 94% of RVI patients had symptomatic RTD, versus 33% in BI and 33% in UE group (p < 0.001), with lower-RTD in 69% of RVI group (p < 0,001). Admission to ICU was 11% in RVI, 17% in BI and 11% in UE group (p = 0.88); only 2 patients required mechanical ventilation (p = 0.37) and no mortality was reported. After an RVI was detected by PCR, antimicrobials were withdrawal in 26% of patients with RVI (p: 0.04). Conclusion: RVI are frequent etiologic agents in febrile episodes of patients with HSCT. Viral detection might help to rationalize the use of antimicrobials in this population.

The Modulation of Mucosal Antiviral Immunity by Immunobiotics: Could They Offer Any Benefit in the SARS-CoV-2 Pandemic?

Viral respiratory infections are of major importance because of their capacity to cause of a high degree of morbidity and mortality in high-risk populations, and to rapidly spread between countries. Perhaps the best example of this global threat is the infectious disease caused by the new SARS-CoV-2 virus, which has infected more than 4 million people worldwide, causing the death of 287,000 persons according to the WHO's situation report on May 13, 2020. The availability of therapeutic tools that would be used massively to prevent or mitigate the detrimental effects of emerging respiratory viruses on human health is therefore mandatory. In this regard, research from the last decade has reported the impact of the intestinal microbiota on the respiratory immunity. It was conclusively demonstrated how the variations in the intestinal microbiota affect the responses of respiratory epithelial cells and antigen presenting cells against respiratory virus attack. Moreover, the selection of specific microbial strains (immunobiotics) with the ability to modulate immunity in distal mucosal sites made possible the generation of nutritional interventions to strengthen respiratory antiviral defenses. In this article, the most important characteristics of the limited information available regarding the immune response against SARS-CoV-2 virus are revised briefly. In addition, this review summarizes the knowledge on the cellular and molecular mechanisms involved in the improvement of respiratory antiviral defenses by beneficial immunobiotic microorganisms such as Lactobacillus rhamnosus CRL1505. The ability of beneficial microorganisms to enhance type I interferons and antiviral factors in the respiratory tract, stimulate Th1 response and antibodies production, and regulate inflammation and coagulation activation during the course of viral infections reducing tissue damage and preserving lung functionally, clearly indicate the potential of immunobiotics to favorably influence the immune response against SARS-CoV-2 virus.

Epidemiology of viral respiratory infections in children undergoing heart surgery.

BACKGROUND: Acute viral respiratory infections (VRI) are the most common diseases in humans and are associated with high morbidity and mortality in infants and the elderly. Children with congenital heart disease (CHD) are more susceptible to get severe forms of VRI due to their altered lung mechanics, leading to several complications, such as increased hospital stay, longer mechanical ventilation, and higher mortality. This study aimed to identify the frequency of VRI in children with CHD undergoing cardiac surgery, and to compare the major outcomes according to the presence or absence of a VRI. METHODS: This was a longitudinal, observational cohort study. Nasopharyngeal secretion samples were collected pre- and postoperatively for patients undergoing cardiac surgery, from May 2013 to May 2014. Respiratory viruses were detected using CLART Pneumovir®. RESULTS: Forty-eight patients were enrolled. We found a VRI preoperatively in 16 children with CHD before surgery (33.3%), and the frequency of new infections was 8.3% (4 patients). However, in this study, in univariate analyses, the two groups did not differ in any of the studied outcomes. In the multivariate regression models, adjusting for age and STAT category, the presence of a VRI did not show a significant effect on the major outcomes. CONCLUSIONS: In conclusion, VRI was frequent in children undergoing open-heart surgery, but the presence of a VRI did not impact on major outcomes in this cohort.

The epidemiology and severity of respiratory viral infections in a tropical country: Ecuador, 2009-2016.

BACKGROUND: Respiratory viral infections (RVI) are a leading cause of mortality worldwide. We compared the epidemiology and severity of RVI in Ecuador during 2009-2016. METHODS: Respiratory specimens collected within the national surveillance system were tested for influenza viruses, respiratory syncytial virus (RSV), adenovirus, parainfluenza virus, and human metapneumovirus. Overall and virus-specific positive detection rate (PDR) were calculated and compared the timing of epidemics caused by the different viruses. Logistic regression models were used to compare the age distribution and risk of death across respiratory viruses. RESULTS: A total of 41,172 specimens were analyzed: influenza (PDR=14.3%) and respiratory syncytial virus (RSV) (PDR=9.5%) were the most frequently detected viruses. Influenza epidemics typically peaked in December-January and RSV epidemics in March; seasonality was less evident for the other viruses. Compared to adults, children were more frequently infected with RSV, adenovirus, parainfluenza, and influenza B, while the elderly were less frequently infected with influenza A(H1N1)p. The age-adjusted risk of death was highest for A(H1N1)p (odds ratio [OR] 1.73, 95% confidence intervals [CI] 1.38-2.17), and lowest for RSV (OR 0.75, 95%CI 0.57-0.98). CONCLUSIONS: Whilst influenza and RSV were the most frequently detected pathogens, the risk of death differed by RVI, being highest for pandemic influenza and lowest for RSV.

Efficacy and safety of withholding antimicrobial treatment in children with cancer, fever and neutropenia, with a demonstrated viral respiratory infection: a randomized clinical trial.

OBJECTIVES: To determine efficacy and safety of withholding antimicrobials in children with cancer, fever and neutropenia (FN) with a demonstrated respiratory viral infection. METHODS: Prospective, multicentre, randomized study in children presenting with FN at five hospitals in Santiago, Chile, evaluated at admission for diagnosis of bacterial and viral pathogens including PCR-microarray for 17 respiratory viruses. Children positive for a respiratory virus, negative for a bacterial pathogen and with a favourable evolution after 48 h of antimicrobial therapy were randomized to either maintain or withhold antimicrobials. Primary endpoint was percentage of episodes with uneventful resolution. Secondary endpoints were days of fever/hospitalization, bacterial infection, sepsis, admission to paediatric intensive care unit (PICU) and death. RESULTS: A total of 319 of 951 children with FN episodes recruited between July 2012 and December 2015 had a respiratory virus as a unique identified microorganism, of which 176 were randomized, 92 to maintain antimicrobials and 84 to withdraw. Median duration of antimicrobial use was 7 days (range 7-9 days) versus 3 days (range 3-4 days), with similar frequency of uneventful resolution (89/92 (97%) and 80/84 (95%), respectively, not significant; OR 1.48; 95% CI 0.32-6.83, p 0.61), and similar number of days of fever (2 versus 1), days of hospitalization (6 versus 6) and bacterial infections throughout the episode (2%-1%), with one case of sepsis requiring admission to PICU in the group that maintained antimicrobials, without any deaths. CONCLUSIONS: The reduction of antimicrobials in children with FN and respiratory viral infections, based on clinical and microbiological/molecular diagnostic criteria, should favour the adoption of evidence-based management strategies in this population.

Impact of Multiplex Polymerase Chain Reaction Testing for Respiratory Pathogens on Healthcare Resource Utilization for Pediatric Inpatients.

OBJECTIVE: To assess whether multiplex polymerase chain reaction (mPCR) vs non-mPCR testing impacts the use of antibiotics, chest radiographs, and isolation precautions. STUDY DESIGN: We retrospectively compared use of antibiotics, chest radiographs, and isolation precautions for patients <18 years old (excluding neonates) hospitalized at a tertiary referral center tested for respiratory pathogens in the emergency department or during the first 2 hospital days, during 2 periods: June 2010-June 2012 (non-mPCR group) vs October 2012-May 2014 (mPCR group). RESULTS: Subjects (n = 2430) in the mPCR group were older, had more complex chronic conditions, and were admitted to the pediatric intensive care unit more often compared with the non-mPCR (n = 2349) group. Subjects in the mPCR group had more positive tests (42.4% vs 14.4%, P < .01), received fewer days of antibiotics (4 vs 5 median antibiotic days, P < .01), fewer chest radiographs performed, (59% vs 78%, P < .01), and were placed in isolation longer (20 vs 0 median isolation-hours, P < .01) compared with the non-mPCR group. In multivariable regression, patients tested with mPCR were less likely to receive antibiotics for ≥2 days (OR 0.5, 95% CI 0.5-0.6), chest radiographs at admission (OR 0.4, 95% CI 0.3-0.4), and more likely to be in isolation for ≥2 days (OR 2.4, 95% CI 2.1-2.8) compared with the non-mPCR group. CONCLUSIONS: Use of mPCR testing for respiratory viruses among hospitalized patients was significantly associated with decreased healthcare resource utilization, including decreased use of antibiotics and chest radiographs, and increased use of isolation precautions.

Application of molecular assay for adenovirus detection among different pediatric patients / Aplicação de teste molecular para detecção de adenovírus em pacientes pediátricos distintos

OBJECTIVE: Adenoviruses play an important role in the etiology of severe acute lower respiratory infection, especially in young children. The aim of the present study was to evaluate the Human Adenovirus (HAdV) detection by different methods (Direct Fluorescence Assay DFA and Nested Polymerase Chain Reaction nested PCR), among samples collected from different groups of pediatric patients. METHODS: Collection of samples was made in children with congenital heart disease (CHD 123 nasal aspirates collected in the years of 2005, 2007 and 2008) and in community children (CC 165 nasal aspirates collected in 2008). Children were eligible if they presented acute respiratory infection (ARI) of probable viral etiology, within up to 7 days of symptoms' onset. All studied samples were evaluated by DFA and nested PCR assay. RESULTS: Of the 290 samples included during the study period, 43 (14.8%) were positive on at least one test: 17/165 (10.3%) of the CC and 26/125 (20.8%) of the CHD children. The nested PCR detection rates in the community children were 15/165 (9.1%), and for children with CHD, 24/125 (19.2%). Molecular method showed higher detection rates when compared to the DFA test (p<0.001). Univariate analysis showed that children with congenital heart disease presented a significantly higher chance for acquiring the HAdV (Odds Ratio 2.3; 95% CI: 1.18-4.43). CONCLUSIONS: Based on data obtained in the present evaluation, we suggest that a routine surveillance should be performed in high risk patients by molecular methods, thus improving diagnostic flow and efficiency.

OBJETIVO: Os adenovírus desempenham um papel importante na etiologia da infecção aguda grave do trato respiratório inferior, especialmente entre crianças. O objetivo do estudo foi avaliar a detecção do adenovírus humano (HAdV) por diferentes métodos (imunofluorescência direta DFA e reação em cadeia da polimerase nested nested PCR) em amostras coletadas de diferentes populações de pacientes pediátricos. MÉTODOS: O material foi coletado de crianças portadoras de doença cardíaca congênita (DCC 123 aspirados nasais coletados em 2005, 2007 e 2008) e de crianças da comunidade (CC 165 aspirados nasais coletados em 2008). As crianças eram consideradas elegíveis se apresentassem infecção respiratória aguda (IRA) de provável etiologia viral, com até sete dias de início dos sintomas. Todas as amostras coletadas no estudo foram avaliadas por meio de DFA e nested PCR. RESULTADOS: De 209 amostras incluídas, 43 (14,8%) foram positivas em pelo menos um dos testes feitos: 17/165 (10,3%) das crianças da comunidade e 26/125 (20,8%) das crianças cardiopatas. As taxas de detecção por nested PCR foram 15/165 (9,1%) em crianças da comunidade e 24/125 (19,2%) em crianças cardiopatas. O método molecular mostrou maiores taxas de detecção quando comparado com a DFA (p<0,001). A análise univariada mostrou que as crianças portadoras de cardiopatia congênita apresentaram chance significativamente maior de adquirir HAdV (odds ratio 2,3; IC 95%: 1,18-4,43). CONCLUSÕES: Baseado nos resultados obtidos na presente avaliação, recomenda-se a vigilância de rotina em pacientes de risco (DCC) por métodos moleculares, que melhora o fluxo diagnóstico e a eficiência da detecção.

[Application of molecular assay for adenovirus detection among different pediatric patients]. / Aplicação de teste molecular para detecção de adenovírus em pacientes pediátricos distintos.

OBJECTIVE: Adenoviruses play an important role in the etiology of severe acute lower respiratory infection, especially in young children. The aim of the present study was to evaluate the Human Adenovirus (HAdV) detection by different methods (Direct Fluorescence Assay - DFA and Nested Polymerase Chain Reaction - nested PCR), among samples collected from different groups of pediatric patients. METHODS: Collection of samples was made in children with congenital heart disease (CHD - 123 nasal aspirates collected in the years of 2005, 2007 and 2008) and in community children (CC - 165 nasal aspirates collected in 2008). Children were eligible if they presented acute respiratory infection (ARI) of probable viral etiology, within up to 7 days of symptoms' onset. All studied samples were evaluated by DFA and nested PCR assay. RESULTS: Of the 290 samples included during the study period, 43 (14.8%) were positive on at least one test: 17/165 (10.3%) of the CC and 26/125 (20.8%) of the CHD children. The nested PCR detection rates in the community children were 15/165 (9.1%), and for children with CHD, 24/125 (19.2%). Molecular method showed higher detection rates when compared to the DFA test (p<0.001). Univariate analysis showed that children with congenital heart disease presented a significantly higher chance for acquiring the HAdV (Odds Ratio 2.3; 95% CI: 1.18-4.43). CONCLUSIONS: Based on data obtained in the present evaluation, we suggest that a routine surveillance should be performed in high risk patients by molecular methods, thus improving diagnostic flow and efficiency.

Respiratory viral infections and effects of meteorological parameters and air pollution in adults with respiratory symptoms admitted to the emergency room.

BACKGROUND: Respiratory viral infections (RVIs) are the most common causes of respiratory infections. The prevalence of respiratory viruses in adults is underestimated. Meteorological variations and air pollution are likely to play a role in these infections. OBJECTIVES: The objectives of this study were to determine the number of emergency visits for influenza-like illness (ILI) and severe acute respiratory infection (SARI) and to evaluate the association between ILI/SARI, RVI prevalence, and meteorological factors/air pollution, in the city of Porto Alegre, Brazil, from November 2008 to October 2010. METHODS: Eleven thousand nine hundred and fifty-three hospitalizations (adults and children) for respiratory symptoms were correlated with meteorological parameters and air pollutants. In a subset of adults, nasopharyngeal aspirates were collected and analyzed through IFI test. The data were analyzed using time-series analysis. RESULTS: Influenza-like illness and SARI were diagnosed in 3698 (30·9%) and 2063 (17·7%) patients, respectively. Thirty-seven (9·0%) samples were positive by IFI and 93 of 410 (22·7%) were IFI and/or PCR positive. In a multivariate logistic regression model, IFI positivity was statistically associated with absolute humidity, use of air conditioning, and presence of mold in home. Sunshine duration was significantly associated with the frequency of ILI cases. For SARI cases, the variables mean temperature, sunshine duration, relative humidity, and mean concentration of pollutants were singnificant. CONCLUSIONS: At least 22% of infections in adult patients admitted to ER with respiratory complaints were caused by RVI. The correlations among meteorological variables, air pollution, ILI/SARI cases, and respiratory viruses demonstrated the relevance of climate factors as significant underlying contributors to the prevalence of RVI.

Patterns of influenza infections among different risk groups in Brazil

Influenza virus infections are associated with high morbidity and mortality. Influenza activity varies worldwide, and regional detection is influenced by geographic conditions, demographic and patient-risk factors. We assessed influenza activity and patterns of seasonality during three consecutive years (2001-2003) in three risk groups in São Paulo city. Four-hundred-twelve outpatients with acute respiratory infection were subjected to epidemiological, clinical and laboratory investigations; these included community population (N=140), health-care workers (N=203), and renal-transplanted patients (N=69). Nasal wash samples were tested by direct fluorescent assay for influenza, parainfluenza, adenovirus, and respiratory syncytial virus. Overall Influenza positivity was 21 percent, and a progressive decline was observed in all groups over time. Influenza A and B co-circulated at the same time in 2001 and 2002, but not in 2003. Low influenza-vaccination rates (19 percent) were reported by health-care workers. Unexpected low levels of etiological agents were detected in renal-transplanted patients, and infected cases were less symptomatic than immunocompetent patients. Based on this study, we conclude that health-care worker-immunization programs should be implemented and the clinical patterns of infected influenza patients should be used as a guide for better case-definition criteria for adequate influenza surveillance, particularly for renal-transplant patients.