title: Respiratory viral infections and effects of meteorological parameters and air pollution in adults with respiratory symptoms admitted to the emergency room.
abstract: 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.
  
  
  OBJECTIVE
  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.
authors.affiliation: Pulmonology Department, School of Medicine, Graduate Program in Pulmonology, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Denise R
authors.initials: DR
authors.lastname: Silva
authors.forename: Vinícius P
authors.initials: VP
authors.lastname: Viana
authors.forename: Alice M
authors.initials: AM
authors.lastname: Müller
authors.forename: Fernando P
authors.initials: FP
authors.lastname: Livi
authors.forename: Paulo de Tarso R
authors.initials: Pde T
authors.lastname: Dalcin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000397:Air Pollution; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008685:Meteorological Concepts; D008875:Middle Aged; D012141:Respiratory Tract Infections / Q000453:epidemiology*; D014777:Virus Diseases / Q000453:epidemiology*
keywords: Air pollution; hospitalizations; influenza-like illness; meteorology; respiratory viral infections; severe acute respiratory infections
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